2. NUTRIENT ADDITIONS TO FOOD - TECHNOLOGY
3. IMPACT OF OTHER TECHNOLOGIES ON FORTIFICATION PROCEDURES
4. VITAMIN AND MINERAL FORTIFICANTS
5. QUALITY ASSURANCE AND CONTROL
6. FUTURE DIRECTIONS OF FORTIFICATION
ANNEX 1 - COMMON CRITICAL CONTROL POINTS IN THE PRODUCTION OF SELECTED FORTIFIED FOODS AND EXAMPLES OF MONITORING PROCEDURES
*This paper was prepared for the Technical Consultation by Dr. Renata Clarke, Consultant in Food Science and Technology.
FAO TECHNICAL CONSULTATION ON FOOD FORTIFICATION:
TECHNOLOGY AND QUALITY CONTROL
ROME, ITALY, 20-23 NOVEMBER 1995
1.1 Forms of Nutritional Intervention
1.2 Food Fortification: A Definition
1.3 Food Fortification in Developed Countries
1.4 Food Fortification in Developing Countries
Before going on to look at the technologies involved in food fortification, it is important to emphasise that there are alternative or complementary forms of intervention which are sometimes indicated in the face of nutritional deficiency. Food based interventions include the establishment of horticultural and home garden projects, whereby support is given to strategic target groups to grow certain crops which could alleviate their dietary deficiency. Such activity has received widespread acceptance (Arroyave, 1987; Smitasiri, 1991; Attig et al., 1993). Nutritional education aimed at getting people to improve their eating habits has also demonstrated positive results in selected situations (Devadas, 1987; Soekirman and Jalal, 1991). Supplemental feeding programmes have also been very successful (Devadas and Saroja, 1985). Development or promotion of superior plant varieties in terms of their micronutrient content as well as the identification of processing technologies which maximise vitamin retention are also important food based strategies (FAO, 1993; Bouis, 1995). Taken individually any of these interventions is inadequate to eliminate micronutrient deficiency. In some cases cultivation of some crops is not widely possible, or the prices of these are out of reach of the most susceptible groups in the population. Also, achieving the necessary results within a reasonable time frame is limited by the fact that in many cases it requires substantial modification of traditional practices. Success in the global context is only possible if a flexible and integrated approach to the problem is adopted.
The distribution of nutrient supplements or clinically administered vitamin doses is sometimes an effective form of intervention in the short term as it can facilitate the more rapid relief of physiological symptoms where additional nutrient demand is high (West, 1987). This strategy depends on the existence of adequate health and social infrastructure.
Food fortification has been defined as the addition of one or more essential nutrients to a food, whether or not it is normally contained in the food, for the purpose of preventing or correcting a demonstrated deficiency of one or more nutrients in the population or specific population groups (FAO/WHO 1994). Other terminology exists for the addition of nutrients to foods. Restoration means the addition to a food of essential nutrients which are lost during the course of Good Manufacturing Process (GMP), or during normal storage and handling procedures, in amounts which will result in the presence in the food of the levels of the nutrients present in the edible portion of the food before processing, storage or handling (FAO/WHO, 1994). Enrichment has been used interchangeably with fortification (FAO/WHO, 1994), but elsewhere it has been defined as the restoration of vitamins and minerals lost during processing (Hoffpauer and Wright, 1994).
Food fortification continues to be a widely used mechanism in many developed countries. In this context, it is the rapidly changing lifestyles and increasing reliance on more highly processed foods has been used to justify the addition of nutrients to an expanding range of foods in order to ensure nutritional adequacy of the diet (LaChance and Bauernfiend, 1991; Hoffpauer and Wright, 1994). It is important to note that there is no general consensus regarding the extent to which food fortification should be practised and the prevailing attitude towards it varies in the developed world. France, the Netherlands, Norway and Finland have restrictive legislation regarding the addition of micronutrients to foods (du Bois, 1991). Nutrification has, however , continued in these countries for certain processed foods. In France restoration of vitamins to compensate for processing losses to the extent of 80 - 200% of naturally occurring levels, is allowed. It is also permitted to add nutrients to foods for special dietary uses. In the Netherlands, addition of nutrients to certain foods for special dietary uses is allowed as well. Vitamin A fortification of margarine and iodine addition to salt are also practised. In Norway and Finland, special permission for nutrient addition to specific foods may be granted (du Bois, 1991). In his recommendations concerning the micronutrient enrichment of foods in the Netherlands, Anderson (1994) stated that the increase in processed ready to use foods had not lowered nutrient intakes in that country and that there was no basis for extending the authorisation for food enrichment. In Germany there is currently an effort to promote the fortification of foods with iodine in order to combat iodine deficiency in that country (Wirth and Kuehne, 1991a; Wirth and Kuehne, 1991b; Schaff, 1993).
In North America, fortification of foods is viewed positively. Many studies underline the role of such nutrified foods in assuring nutritional adequacy in the North American diet (Wiemer, 1995). The expanding range of fortified foods can be justified by the fact that RDA's for many nutrients are commonly not met (NRC, 1989). In a study carried out on a group of women in New York, it was shown that the mean intakes of Ca, Fe and vitamin D were all below the recommended daily allowance (Subar and Bowering, 1988). Other factors can complicate food fortification policy, however, as was shown by the USA National Dairy Council's request for monitoring of Ca fortification on the basis that the required element is readily available in dairy products (Anon., 1995). In developed countries, regulation of fortification is currently receiving more attention than the technologies involved. This is because there is a legitimate fear of over-fortification as manufacturers seek to use fortification as a marketing tool.
Whatever are the issues that now surround food fortification in developed countries, there can be no question of the role which this practice has played in the past. The virtual elimination of micronutrient deficiencies from these countries has been attributed in large part to this action (Finch and Cook, 1981; Bauernfiend and DeRitter, 1991; DeRitter, 1991; LaChance and Bauernfiend, 1991; Hoffpauer and Wright, 1994; Wiemer, 1995).
Food scientists have risen to the challenges posed by micronutrient fortification. Evidence of their success is clearly demonstrated on the supermarket shelves in most developed countries. Technical problems such as the interaction of the added nutrients with the food carrier matrix due to the pro-oxidant and catalytic properties of many of the essential minerals as well as the susceptibility of many vitamins to destruction by heat, light and oxygen have been overcome for an ever widening range of applications.
The 1992 ICN conference held in Rome emphasised the importance of food based activities in their plan of action geared at addressing the issue of micronutrient malnutrition (FAO/WHO, 1992). Food fortification is one of the relevant modes of action. Advantages of food fortification relative to other modes of intervention have been widely noted and a result of these is that fortification programmes can be implemented and yield results within a short period (Austin et al., 1981; Arroyave, 1987; INACG, 1990; Mannar, 1991; Nestel, 1993). The focus of the international community has so far been on the three most prevalent deficiencies: vitamin A, iodine and iron. There are different considerations involved in the establishment of food fortification programmes in developing countries as opposed to developed ones. There are several steps in the implementation of a food fortification programme in developing countries. Having identified the need for nutritional intervention on behalf of a population or a sub-group thereof and the required levels of fortification, then a suitable carrier must be identified, appropriate fortificants selected, the technologies used in the fortification process determined and some mechanism put in place to determine whether the nutritional objectives of the programme are being met. Selection of the carrier is a critical step and several required characteristics of the carrier have been noted (Arroyave, 1987; Mannar, 1991; Nestel, 1993).
The identified vehicle must be consumed in roughly constant quantities throughout the year by the majority of the population. The food must pass through a centralised point to facilitate a rigidly controlled fortification process. The addition of fortificants at the required levels must not affect the organoleptic qualities of the food.
It is important to emphasise that micronutrient fortification is not universally applicable. In some cases the high degree of decentralisation of food processing activities makes it impossible to regulate or even establish a viable fortification programme. In cases where subsistence farming is practised, fortification is not likely to be a practicable solution to nutrient deficiencies. It is imperative, before embarking on food fortification activity, to carefully define the context in which it is indicated.
2.1 Cereals and Cereal based products
2.2 Milk and Milk Products
2.3 Fats and Oils
2.4 Accessory Food Items
2.5 Tea and Other Beverages
2.6 Infant Formulas
The following is not an exhaustive review of all food products which are fortified. Food products have been selected for discussion on the basis of their nutritional impact or their applicability to fortification programmes in developing countries.
2.1.1 Rice and other whole cereal grains
2.1.2 Flours, cornmeal and bread and pasta
2.1.3 Breakfast cereals
This is one of the most important areas for consideration of food fortification technologies. Foods from this category form the major component of diets around the world. This is especially true in the case of developing countries where dietary diversity is limited. On average, cereals provide 52% of caloric intake globally. For Africans and Asians they represent 60-75% of the caloric intake; for Latin Americans, 50%; and in the United States of America, 26% (Bauernfeind and DeRitter, 1991). In developing countries 95% of the population consume cereals as a dietary staple which also provide about 47% of the per capita protein intake.
Milling of cereal grains prior to their consumption is a common practice. During the milling process a substantial proportion of the nutrients are lost from the refined product. The fortification/enrichment of cereal grains can therefore be rationalised in more than one way. One valid reason is to restore to refined products, nutrients which have been removed during the milling process. Another reason is to improve the nutrient intake levels of target populations which are at risk of micronutrient deficiency.
Among the cereals, rice presents unique problems in fortification. These are due to the fact that it is most commonly consumed as a whole grain and also in many countries, extensive washing of the grain prior to cooking is the normal practice. The earliest methods of rice enrichment involved the production of parboiled and converted rice. By this means nutrients from the bran layer were transferred to the starchy endosperm. The parboiling process involved the soaking of the rough rice , the application of heat followed by drying and milling. It was demonstrated that in this way 50-90% of the thiamine was retained (Misaki and Yasumatsu, 1985). The process for converted rice developed by Huzenlaub (Misaki and Yasumatsu, 1985) was similar to that for parboiling, but also employed pressure differences to facilitate transfer of nutrients. Acid parboiling, described by Kondo (Mitsaki and Yasumatsu, 1985) was similar to the parboiling except that it was carried out in the presence of acetic acid.
After parboiling and converting, the next methods of enrichment involved the actual addition of nutrients to the milled products. Techniques used for this have been classified into two main groups 'powder type' and 'grain type' enrichment (Hoffpauer, 1992; Hoffpauer and Wright, 1994).
In powder type enrichment, a powdered pre-blended mixture of vitamins and minerals has been added at a rate of 1, 0.5. or 0.25 oz. per 100 lbs of rice (a w/w ratio of 1:1600, 1:3200 or 1:6400). For white parboiled rice, the normal practice has been to add the premix soon after milling as the heat and moisture at the grain surface at this point facilitates adherence of the powder. A major disadvantage of this method of nutrient addition has been that 20-100% of the nutrients are lost on washing. In the USA, rice enriched in this way must bear a label stating 'to retain vitamins do not rinse before or drain after cooking'.
In the second major type of enrichment, a powdered nutrient mixture has been applied to the milled rice grains followed by coating with a water insoluble substance (Cort et al., 1976; Hoffpauer, 1992). A fortified rice premix produced in this way has then been added to milled rice at a rate of 0.5%, to yield an enriched product conforming to the required standard of identity. In the United States of America, this standard requires between 2.0 - 4.0 mg of thiamine, 1.2 - 2.4 mg of riboflavin, 16 - 32 mg of niacin or niacinamide and 13 - 26 mg of iron per 100 lbs. of rice. It may contain 250 -1000 USP units of vitamin D and 500 -1000 mg of calcium. The requirement regarding riboflavin has been stayed pending final action. The objections regarding the use of this vitamin in the premix have been due to its role in the colour deterioration of the enriched grain. 'Grain type' or 'coated grain' enrichment have also been carried out by spraying the premix solution onto the rice which is contained in a rotary cylinder, followed by hot air drying of the rice, application of a water insoluble sealant, addition of the iron compound and finally a second application of the water insoluble compound (Bauernfeind and deRitter, 1991; Cort et al. 1976). Water insoluble coatings which have been reported include an ethanol or isopropanol solution of zein, palmitic or stearic acid and abeitic acid. Other coating materials have contained ethyl cellulose. They dissolve at the elevated temperatures employed during cooking (Bauernfeind and deRitter, 1991). Using this 'coated grain' procedure, Cort et al. (1976) and Rubin et al. (1977) were able to successfully enrich rice with niacin, thiamine, pyridoxine, vitamin A, vitamin E, folic acid, iron, and zinc using expanded versions of the procedures already described. The water insoluble vitamins and minerals were added in different layers with intermittent coatings of shellac. Stability to rinsing treatments were reportedly high, with vitamin losses in the range of 0.2-1.1%.
Ricegrowers Co-operative Ltd. (RCL) in Australia revised the HLR rice fortification procedure for the enrichment of rice with thiamine, niacin and iron (Bramall, 1986). The HLR process involved dissolution of vitamins in dilute sulphuric acid, application of vitamin solution to rice, application of a water insoluble substance, application of ferric pyrophosphate and talc followed by reapplication of a water insoluble layer and iron mixture before screening and packaging. Due to increased cost of raw materials, low factory output, use of hazardous materials, reported problems with browning of enriched grains, RCL modified the procedure to include the application of the nutrient mixture to the rice followed by drying, screening and packing. The nutrient mixture was composed of ferric pyrophosphate suspended in an acid solution of the vitamins. They reported that the browning found in the HLR premix on storage was due to the formation of ferric sulphates and that this problem was eliminated with the use of an alternative acid. Acid hydrolysis at the surface of the rice grain provided a sufficiently sticky surface to ensure adhesion of the iron compound. Cost of the process was reduced and the factory output was doubled. There was no mention, however, of the stability of premix to nutrient loss through rinsing.
In the Philippines, attempts at fortifying rice by application of vitamin A followed by a water insoluble layer were abandoned since washing losses of between 10 - 20% were recorded (Florentino and Pedro, 1990; Murphy et al., 1992). Rice fortification with iron has also been tried in the Philippines using the coating method. The fortificant used in this programme was anhydrous ferrous sulphate. Some discolouration was found after 20 weeks of storage at room temperature and washing losses were 9%.
Ferric orthophosphate (white iron) is a recommended form of iron for use in the fortification of rice (Hoffpauer, 1992). This iron compound is almost water insoluble and has been preferred for mixing with milled rice due to its white colour. When it is oxidised or contains excessive moisture it may become tan, yellow, purple and or black. Hurrel (1985) reported that the bioavailability of ferric orthophosphate varied widely from batch to batch and was highly negatively correlated with particle size as was also found with elemental iron. This fortificant compound is more expensive than anhydrous ferrous sulphate. According to Hurrel (1985) the cost of ferric orthophosphate was about six times that of anhydrous ferrous sulphate, for the same level of total iron.
In Japan, a multinutrient enriched rice has been on the market since 1981. The first step in this procedure was acid parboiling in the presence of thiamine, riboflavin, niacin, pantothenic acid and pyridoxine. The second step involved coating the grain with separate layers of vitamin E, calcium and iron in separate layers and finally a protective coating material (Misaki and Yasumatsu, 1985). Modified atmosphere packaging, utilising aluminium laminate and carbon dioxide, ensured the stability of vitamin E during storage. The yellow or brown colour of the premix was not a problem in this case as it was used in the fortification of 'brown' rice.
Apart from these well established procedures there have been other innovations regarding alternative methods for rice fortification. Joseph et al. (1990) described an enrichment procedure using a premix containing thiamine, riboflavin, niacin and pyridoxine. This procedure involved soaking the milled rice in an acid medium containing the water soluble vitamins followed by the cross linking of starch granules in the enriched grains. The cross linking procedure itself was demonstrated to have caused significant vitamin loss, but the added vitamins were highly cook and wash stable. It is possible that this method could have some utility in the future.
Use of fortified simulated grains has featured prominently in attempts at rice fortification in the developing countries. Murphy et al. (1992) described the production of such a fortified rice product for use in the Philippines. The synthetic rice grains were produced by extrusion of rice flour in a pasta machine. The best formulation contained vitamin A stabilised by a mixture of tocopherol, ascorbate and lipids with a low level of unsaturation. Retinyl palmitate stabilised in an acacia matrix, type 250 SD (Sigma Chemical Co.) was the fortificant used. Retention of vitamin A after washing was reported to be 100%. Vitamin retention after cooking, however, ranged from 60 - 94%. The formulations which demonstrated the better storage stability, particularly at high humidity, suffered greater cooking losses. Drawbacks with this technology have been reported to exist with respect to blending with the natural product and in the consistency of the simulated grains after cooking (Murphy et al., 1992; Hoffpauer and Wright, 1994). Field trials in Brazil showed no problems with acceptability of rice enriched in this way (Flores et al., 1995).
The enrichment of whole wheat grains with vitamin A has been attempted (Combs et al., 1994). The fortificant used was a premix comprised of concentrated vitamin A attached to wheat grains, for mixing at a level of 0.25% with wheat grains. The feasibility of this procedure was not determined. The fortification of whole grain cereals with soluble iron compounds is difficult because they promote oxidation of the lipid component of the grain, thus reducing the shelf life.
In the fortification of flour the required nutrient mixture is mixed with an appropriate diluent to produce a premix, which is then accurately metered into the flour. The addition of vitamins B1 and B2, niacin, iron and calcium to wheat flour is a common practice in many developed countries. It is technologically feasible to add other vitamins and minerals as well. Cort et al (1976) successfully used two premixes to fortify wheat flour; the first comprised vitamin A, pyridoxine, folic acid, tocopherol acetate, thiamine, riboflavin, niacin and iron while the second contained calcium, magnesium and zinc.
The vitamin/iron premix demonstrated excellent stability on storage. The flour enriched with both premixes also demonstrated excellent stability on storage at room temperature. Under conditions of accelerated storage at elevated temperature (45 °C), however, there was substantial loss of vitamin A beyond 4 weeks of storage. Parrish et al. (1980) also reported good stability of enriched wheat flour stored at room temperature, but about 50% losses in flour stored at 40 °C for 6 months.
The form of vitamin A most commonly used in the fortification of flour was dry stabilised vitamin A palmitate (type 250-sd) powder form. The water soluble vitamins (thiamin, riboflavin, niacin, pyridoxine, folate and calcium pantothenate) are used in pure crystalline form. The mononitrate salt of thiamine is preferred for this use. Iron is normally used in its reduced elemental form. In the work of Parrish et al. (1980) ferrous sulphate was also used as the source of iron and there was no significant difference demonstrated between the flour enriched with ferrous sulphate and that enriched with elemental iron. It has been recommended that ferrous fumarate be used in the fortification of wheat flour within the P.L. 480 programme, due to its greater bioavailability (Combs et al., 1994). When mixing dry fortificants with dry foods, careful selection of the physical characteristics of the fortificant compound is important so as to ensure adequate mixing and to minimise segregation on storage.
Rubin et al. (1977) investigated the stability of bread made from flour enriched by the 6 vitamins and 4 minerals described by Cort et al. (1976). They found that the inclusion of calcium and magnesium adversely affected vitamin A retention during the baking process. There was also an off-flavour detected in bread which included magnesium after 5 days of storage. Crumb colour and grain were also negatively affected by the nutrient multimixes tested by Rubin et al. (1977), with the greater affect occurring with the nutrient mix which included magnesium. Fortification of bread with zinc salts exerted no adverse effect on loaf volume, flavour or any other index of bread quality (Ranhotra, 1976).
Iodisation of bread has been carried out in the Netherlands and Tasmania (Dunn et al., 1986) by the addition of 2-4 ppm KIO3 to the bread improver which was already in general use. KIO3 has been used in bread production in the past, not as a fortificant but as an oxidising agent to improve dough quality.
The fortification of corn meal with 6+4 vitamin/iron mixture was shown to be technically feasible (Rubin et al., 1977; Parrish et al., 1980). Losses of vitamin A on storage at room temperature for up to six months were greater than with wheat flour but still remained below 20%.
In many countries pasta or noodles are commonly eaten and these can therefore be important vehicles for fortification. The manufacture of such products involves the production of a dough which is then extruded and dried. Enrichment can be through the use of enriched flour or alternatively, wet addition of a dispersion of the required vitamins can be carried out at the dough-making stage. Vitamin losses during production depend largely on the drying conditions employed. Dexter et al. (1982) enriched durum wheat flour with a vitamin mixture containing riboflavin, thiamine mononitrate and niacin for the production of spaghetti. They reported that high temperature drying treatments resulted in significant losses of riboflavin, whereas the other vitamins were stable to the processing conditions. In all cases cooking losses, estimated between 40 - 50%, exceeded those experienced during processing.
The fortification of ready to eat breakfast cereals is a wide-spread practice. In the United States the general practice has been to provide 25% of the RDA of thiamine, riboflavin, niacin, pyridoxine, folate, ascorbic acid and vitamin A per 1 ounce. 10 or 25% iron, up to 20% RDA for calcium have also been added; vitamin D has also sometimes been included (Bauernfeind and DeRitter, 1991). Surveys have indicated that fortified breakfast cereals play an important role in ensuring nutritional adequacy of the diets of the U.S. population (Wiemer, 1995).
The minerals and the more heat stable vitamins like niacin and riboflavin have been added to the basic formula mix prior to processing (Johnson et al., 1988). The heat labile vitamins such as vitamins A, C and thiamine are usually sprayed onto the cereals after the high temperature processes such as oven or extruder. According to Johnson et al. (1988) two important considerations in the design of the spray system are: i) to ensure uniformity in spray coverage and ii) to optimise protection of both vitamins A and D. As the hydrophobic vitamins cannot form true aqueous solutions, they have been sprayed on in the form of an emulsion. The composition of the emulsion has been shown to greatly affect the vitamin stability. The inclusion of 15-20% sucrose into the spraying emulsion stabilised the vitamin A. It acted by forming a protective coating around the vitamin on drying. This fact explained the greater stability of vitamin A included in raisin bran as compared with cornflakes (Johnson et al., 1988). In the latter case a no-sugar spray was used. Vitamin E can be added to the spray emulsion, it was at least as stable when added under these conditions.
Good storage stability of the fortified breakfast cereals was reported (Anderson et al., 1976). This was partly due to the fact that packaging materials with appropriate barrier properties have to be selected to ensure the maintenance of equilibrium moisture contents below about 5 %. Above this level there was textural deterioration of the product which was perceived as 'staleness'. Lund (1991) reported almost 60% loss of vitamin C from raisin bran on storage for a 12 month period. This was ascribed to the fact that the moisture levels in this cereal were maintained at a higher level to prevent hardening of the raisins. Improved procedures for the coating of raisins with a moisture barrier material prior to mixing with the material can minimise this problem. The addition of ascorbic acid was found to stabilise vitamin A to a greater extent than did phenolic antioxidants (Anderson et al., 1976). The addition of tocopherols did not provide any additional stability, possibly because they were already present at optimal levels.
2.2.1 Liquid milk
2.2.2 Powdered milk
2.2.3 Other dairy products
The production of a large proportion of milk on the market involves the removal of cream. Along with the cream, much of the fat soluble vitamins are also removed. The fortification of milk commonly involves the addition of vitamins A and D.
Since milk is an oil-in-water emulsion, the possibility exists to add vitamins in their oily form or use water dispersable forms of these. Ease of mixing has been identified as an advantage of using dry, water dispersable forms of the fortificant. However, the disadvantage of this was that vitamins were less stable in this form after addition to the milk as the protective coating dissolved leaving the vitamin susceptible to degradation (O'Brien and Robertson, 1993). Addition of oily vitamin preparations was recommended after dilution and pre-homogenisation with a suitable quantity of milk. Addition of the vitamin mixture prior to homogenisation of the bulk supply, facilitates uniform mixing. Metered injections of the vitamin preparation upstream to the homogeniser has been the standard set up in continuous operation plants. As both of these vitamins are sensitive to oxidation, care must be taken to minimise aeration particularly during mixing stages.
Many iron compounds have been assessed in the fortification of pasteurised whole milk. At pasteurisation temperatures below 79 °C off-flavours due to lipolytic rancidity developed but these problems were greatly reduced by increasing the pasteurisation temperature to 81 °C (Owen and MacIntire, 1975). De-aeration of the milk prior to the addition of iron compounds was also found to reduce flavour problems. The best fortification procedure was judged to be the addition of ferric ammonium citrate followed by pasteurisation at 81 °C. In this way fortified milk containing 30 ppm iron was found to be acceptable after 7 days storage. Levels of vitamin E, vitamin A and carotene were not affected by the presence of iron. In the production of iron fortified evaporated milk, ferric orthophsphate was shown to be useful (Krutz, 1973). The uniform distribution of the iron compound was, however, identified as a problem due to its low solubility.
Calcium fortification of milk and milk-based beverages has been carried out. Calcium fortificant preparations including stabilisers and emulsifiers have been used for this purpose to maintain calcium in suspension so as to improve mouthfeel and appearance of products (Anon., 1986). In Germany a milk-based fruit beverage has been marketed which is fortified with calcium, phosphorous as well as vitamins A, E, B and C.
The fortification of powdered milk has been achieved by the addition of dry vitamin preparations to the milk powder as well as by vitamin addition to the liquid milk just prior to spray drying. As with other dry products, effective mixing has been best achieved in two steps: the initial dilution of the vitamin mixture with a suitable quantity of milk powder, followed by mixing into the bulk. Consideration of particle size and density are important to prevent separation of the components on storage.
In the iron fortification of powdered non-fat dry milk, ferrous sulphate at a level of 10 ppm was found to be stable for a period of 12 months. Ferric ammonium citrate and ferric chloride at a level of 20 ppm iron in the reconstituted product gave acceptable results (Coccodrilli and Shah, 1985).
The addition of vitamins to other dairy products such as yoghurt and ice-cream has been practised and enrichment of cheese with iodine through the use of iodised salt has been approved in Germany.
In the case of ice-cream, there were no technological difficulties to overcome. The unit operations used in the manufacture of ice-cream are not highly destructive to vitamins. Vitamins are added in the dry form to the mix. Since whipping and consequent aeration of the mix is carried out around freezing temperature, oxidative losses of vitamins are minimal. Perhaps the greatest processing losses are due to pasteurisation of the mix.
In the production of yoghurt, the low pH conditions render it unsuitable as a carrier for vitamins such as vitamin A (O'Brien and Roberton, 1993). The water soluble B-vitamins are best used in a coated form, protected for odour and flavour considerations. When vitamins are added to the yoghurt by addition to the base, some vitamin loss can occur through metabolism by fermentation microorganisms (O'Brien and Roberton, 1993).
Margarine is a spread which has been widely used interchangeably with butter. For this reason, in many countries fortification of this spread with vitamins A and D is practised, since the food that it replaces is a good source of these vitamins. The vitamin A requirement is met using B-carotene as well as oil soluble vitamin A esters (Bauernfiend, 1991). The oil soluble vitamins are added in the required amounts to a portion of warmed oil which is then added to the bulk prior to homogenisation. Particularly in the case of margarines with a high content of polyunsaturated fatty acids, vitamin E has also been added. Due to the mild processing conditions only small overages are required to compensate for processing losses: 10 % for vitamins A and D and between 5-15% for vitamin E (O'Brien and Robertson, 1993).
Fortification of oil with vitamin A in the form of retinyl palmitate has been attempted in Brazil (Nestel, 1993). Storage studies demonstrated that after 18 months of storage in dark sealed containers losses of more than half of the vitamin content were experienced. When storage was not carried out in the dark, most of the vitamin content was lost after 6 months. Packaging of the fortified oil in opaque containers was therefore demonstrated to be a critical consideration.
Vitamin A fortified oil showed good vitamin retention after 5 months of storage in sealed metal containers at high temperature and humidity (Combs et al., 1994). Partially hydrogenised vegetable oil was used in the study and the fortificant was all-trans retinyl palmitate, at a level of 491 m g. 10 g. BHA and BHT were used as antioxidants
2.4.2 Monosodium glutamate
Although staple foods are generally used as vehicles in food fortification programmes, at times when none can be identified which has all the required characteristics, it has been necessary to find other options. In outlining fortification policy in the Philippines, Parce (1995) states that condiments may be fortified but only with nutrients that are deficient in the diet and provided that such food is an appropriate vehicle for the micronutrient and is widely consumed by the general population or is intended for intervention programmes to address deficiency in a specific target population.
Salt iodisation began in 1922 in Switzerland and has been implemented in many countries as the major mechanism for eliminating iodine deficiency. Today, IDD remains a problem in many countries. WHO and UNICEF have established the goal of 'Universal Salt Iodisation' to be achieved by the end of 1995. Salt has been favoured as a carrier for iodine due to its wide spread coverage, effectiveness, simple technology involved and low cost (Mannar, 1988). Based on the suitability of salt as a widely used and low cost vehicle, fortification of salt with other nutrients has also been attempted (Nestel, 1993; Rao, 1985).
According to the Codex standard for food grade salt, use can be made of potassium or sodium iodides and iodates (FAO/WHO, 1995). The iodates have been found to be more stable than the iodides under a wide range of conditions. Stability studies of iodised salt using potassium iodate as the fortificant demonstrated that there was no significant loss of iodine on storage in polyethylene bags for up to two years (Chauhan et al., 1992; Silveira, 1993) and that boiling of the salt solutions led to negligible iodine loss.
There have been four major technologies used in the addition of iodine to salt. These are dry mixing, drip feed addition, spray mixing and submersion: the salient features of these procedures have been described by Mannar (1988). A thorough review of salt iodisation technology and quality control has been included in the recent text by Mannar and Dunn (1995).
According to Bauernfeind (1991), an acceptable iron fortificant for salt is one which does not discolour the salt nor impart a flavour or odour and remains stable and bio-available on storage. Ferrous fumarate, ferric orthophosphate and ferrous pyrophosphate have all been recommended by INACG (Nestel, 1993) for use with salt. Cook and Reuser (1985) report that the use of sodium acid pyrophosphate, ferric orthophosphate and ferric pyrophosphate as unacceptable due to poor bioavailability. To circumvent this problem, iron absorption enhancers, such as ascorbic acid and sodium acid sulphate, have been used. Another possibility is to use less stable iron compounds in conjunction with a stabiliser. Such combinations include ferrous sulphate/hexametasulphate and ferrous sulphate/sodium acid pyrophosphate. Sodium ferric EDTA provides adequate amounts of iron, but has been found to discolour refined salt (Cook and Reuser, 1985).
In the fortification of salt with iron, it must first be ground to a coarse powder to facilitate uniform mixing and distribution of the iron fortificant. Rao (1985) reported that a ribbon blender or a screw type conveyor mixer with a suitable feeder could be used. He also reported that packaging in unlaminated high density polythene bags was found to be satisfactory. The addition of both iodine and iron fortificants to salt can lead to the decomposition of the iodine compound and its subsequent liberation (Rao, 1985; Nestel, 1993). Nestel (1993) reported on the use of a fortificant mixture containing 40 ppm of potassium iodate, and 1000 ppm of iron as ferrous sulphate and 10,000 ppm of a permitted stabiliser which rendered good bioavailability of both iodine and iron after prolonged storage. Cost was identified as a constraint in the use of this fortificant system as it added 50% to the retail price of salt.
Fortification of salt with vitamin A has been attempted under laboratory conditions (Nestel, 1993). The fortificant used was dry vitamin A palmitate type 250 SD protected by a lipid. The fortificant was found to be unstable at moisture contents above 2%, since salt is hygroscopic, packaging material with an adequate moisture barrier must be used. Impurities in the salt were also found to destabilise the vitamin A. The particle size and shape must be such that uniform mixing could be achieved and segregation does not occur on storage.
MSG is a condiment which is widely used in many Asian countries. It has GRAS status in Codex Alimentarius as a flavour enhancer. This additive has been thoroughly scrutinised due to the allergic response which it has been alleged to induce in susceptible individuals (IFT, 1987; Alien, 1991). Recent studies have indicated that it is safe for the vast majority of people (IFT, 1987; Tarasoff and Kelly, 1993). It is worthy of note that the Joint Expert Committee on Food Additives concluded that MSG should not be used in infant foods even though there was no cause for concern about health risks (FAO/WHO, 1987).
Field studies on MSG fortification with vitamin A have been conducted in the Philippines and Indonesia (Bauernfeind, 1991; Nestel, 1993). In the Philippines dry vitamin A type 250 SD was used. This is vitamin A palmitate stabilised in an acacia-lactose matrix. The MSG was first ground to 100 mesh to facilitate mixing with the fortificant. Problems were encountered with segregation of fortificant and carrier, loss of vitamin A activity and colour deterioration of the fortified product. Vitamin A acetate 325 L, a granular fortificant stabilised in a gelatin - sucrose matrix, was used in place of the finely powdered vitamin A palmitate 250 SD. Under conditions of high humidity, there was hardening of the gelatin coat with associated loss of vitamin potency. In the Indonesian study, dry vitamin A palmitate type 250 CWS dispersed in an edible carbohydrate, stabilised with antioxidants and coated with a white protective layer, was used. This product was hot and cold water miscible. This fortificant was demonstrated to retain over half of its potency when stored at 25 °C for 18 months. Under moist dark conditions, half of the activity is retained after 7 months. When subjected to light the fortificant is destabilised more rapidly, the uncoated form of the vitamin is less stable under these conditions. The fortificant mixture was added to MSG at the rate of 0.171 wt. %. The vitamin A was aggregated into clusters so as to minimise the problem of segregation during mixing and storage. Segregation of the product was still, however, identified as a problem. Colour deterioration of the fortified product was another constraint to the continued application of this technology (Soekirman and Jalal, 1991).
Iron fortification of MSG has also been attempted using micronised ferric orthophosphate and zinc stearate coated ferrous sulphate (Bauernfeind, 1991). The coated ferrous sulphate had reduced bioavailability relative to the uncoated form (Garby, 1985), but the fortified product was judged to have acceptable colour, taste, bioavailability and particle size properties. Preliminary investigations indicated that the inclusion of dry stabilised vitamin A (type 250 SD) into the iron fortified mixture might be technically feasible.
Sugar has been found to be a suitable vehicle for nutrients in fortification programmes in Latin America and the Caribbean. In the vitamin A fortification of sugar, vitamin A 250-CWS was proven to be the most effective fortificant. The premix is produced by mixing sugar and fortificant in a revolving drum mixer. Physical separation of the fortificant beadlets from the sugar was prevented by the addition of an edible bonding agent. Stabilisers are added by first dissolving in warmed oil under anaerobic conditions, achieved by bubbling nitrogen through the oil, followed by intermittent addition to the fortified sugar with continuous mixing. Peanut, cotton seed, soya bean and coconut oils have all been used in this procedure. It has been suggested that shark liver oil be used in place of the vegetable oils. The natural vitamin A content of this source reduced the need for vitamin A fortificant by 10-12% (Lacera et al. 1983). The successful use of shark oil would be expected to require rigorous deodorising and refining treatments and stabilisation of polyunsaturated fatty acids. Satisfactory storage stability of the premix was obtained when packaged in double polyethylene bags with an outer paper layer, and stored in a cool, dry place.
The premix was added to the sugar such as to achieve vitamin A levels of 50 IU per g in the final product (Molina, 1991). Addition of fortificant can take place in the centrifuge at the end of the washing cycle in the sugar refining process, or along the transporting belts prior to packaging. Retention of vitamin A after 6 months at 25 °C was 92%. Higher losses were recorded with storage at 45 °C, with 76% retention of vitamin activity after 3 months.
Fortification of sugar with iron has also been attempted. Bauernfeind (1991) reported promising results using sodium ferric EDTA as the fortificant. Segregation of the fortificant and the carrier was not a problem as the iron compound became stuck to the sugar crystals at moisture contents exceeding 1% (Cook and Reuser, 1985). A major problem which exists with iron fortified sugar is that on addition to coffee or tea, there is marked discolouration. This phenomenon is reduced with the use of NaFeEDTA, but it is still evident.
Iron fortification of strongly flavoured or dark coloured food products is often simplified due to the fact mat less care is required in consideration of the avoidance of off-flavours and off-colours. Largely for this reason iron fortification of curry powder demonstrated no technical difficulties. Nestel (1993) reported that NaFeEDTA was the fortificant used in the enrichment of curry powder in South Africa. In the fortification of fish sauces the major problem was the formation of a precipitate on addition of iron. When sodium iron EDTA was the fortificant, however, this phenomenon was greatly reduced. The inclusion of iron in an EDTA complex greatly restricted its availability for interaction with macro-molecules and other compounds in foods which could eventually lead to precipitation or other deteriorative reaction.
2.5.2 Fruit juices and drinks
Brooke and Cort (1972) have reported on two procedures for the fortification of tea. Fine powdered vitamin A palmitate 250 SD was used by dry mixing with the tea dust. An emulsion of vitamin A palmitate, diluted with 50% sucrose solution was sprayed onto tea leaves. The added vitamin showed excellent storage stability for periods up to 6 months, and showed 100% recovery after brewing.
In most cases the pH of fruit drinks and juices is below 4.5 and the heat treatment required is pasteurisation. Some loss of heat labile vitamins, thiamin, folic acid and ascorbic acid, occur as a result of the thermal treatment. The acidity of these drinks causes problems of stability with vitamin A, folic acid and calcium pantothenate. Carbonation of these beverages, with the resultant exclusion of oxygen, improves the stability of vitamins. The presence of sulphur dioxide in the fruit juices used in the production of these beverages have been shown to have a detrimental affect on thiamine content (O'Brien and Roberton, 1993).
Precautions which should be taken in the production of fortified liquid beverage have been outlined by DeRitter and Bauernfeind (1991). These included the use of stainless equipment, addition of vitamins at the latest possible stage, avoidance of excessive aeration or even de-aeration, rapid cooling after thermal treatment and the avoidance of readily autooxidisable ingredients. Data reported from a storage stability test of pasteurised multivitamin orange juice demonstrated 50% loss of vitamin A after 6 months of storage whereas B-carotene showed only about 6% loss. Riboflavin and thiamin showed good stability but vitamin C showed about a 23% loss (O'Brien and Roberton, 1993). Frozen orange juice concentrate containing added vitamins A, B1, and C showed no vitamin A loss after holding at --10°F for 6 months (DeRitter and Bauernfeind, 1991). Beta-carotene and apocarotenal both showed good stability in fortified drinks but the latter was less stable on exposure to sunlight.
Problems associated with the iron fortification of fruit juices and drinks have been outlined as follows (Coccodrilli and Shah, 1985):
i. accelerated loss of vitamin C
ii. flavour and taste deterioration in the presence of thiamine, folic acid, vitamin A and vitamin C
iii. levels of fortification beyond 2.7 mg per serving result in metallic off-flavours
iv. decolourisation of some pigments.
The stability of a powdered breakfast drink fortified with iron, vitamin A and vitamin C was found to be very good. For organoleptic considerations ferrous gluconate was found to be superior to ferrous sulphate.
Fortification of beverages with calcium has become a popular practice. Minerals with a high nutritional requirement such as Ca, Mg and P create problems in the development of fortified foods (Clydesdale, 1991). Insoluble Ca and Mg salts cause lightening of food colour, whereas soluble salts may interact with other food components such as tannins to cause darkening. Minerals have also been reported to interact with anthocyanins containing vicinal hydroxyl groups causing a red to blue colour change (Clydesdale, 1991). At the required levels of fortification sparingly soluble compounds such as tribasic calcium phosphate, calcium sulphate and magnesiun oxide can cause chalky flavours. Conversely, the use of more soluble salts can lead to astringency due to high levels of the calcium and magnesium ions. The pro-oxidiant effect of many minerals have caused rancidity development in lipid-containing beverages. In 'slimming ' preparations or other beverages with a high protein content, the addition of Ca or Mg salts have caused destabilisation of the protein component. Hirotsuka et al. (1984) reported on the use of soy lecithin to coat calcium ions for use in the calcium fortification of soy milk. This procedure prevented the Ca induced precipitation of soy proteins.
An adapted formula is designed to supply the total energy and nutrient requirements of full-term healthy infants during the first year of life. A follow-up formula designed to be a part of a mixed feeding regimen, can sometimes be introduced after 4-6 months. Other specialised formulas have been produced which take into account specific nutritional problems of infants.
The mineral content of cow's milk, from which many formulas are produced, is highly variable. Production methods have been adapted to control this source of variability. Operations have been included which remove most of the minerals, but at the same time some vitamins and other components of the milk are lost: technologies used include ion exchange, ultra filtration, electrodialysis, reverse osmosis and gel filtration. Mineral compounds are then added at the required levels. There must be careful selection of mineral compounds added to the formulas, as cereal products are highly susceptible to lipid oxidation during storage. In a study of iron fortification of infant cereals, Hurrell et al. (1989a) proposed the use of ferrous fumarate and ferrous succinate as they gave rise to no objectionable flavours odours or colours on storage. Ferrous sulphate coated with hygrogenated fats, mono- or di-glycerides and ethyl cellulose caused discolouration on reconstitution with hot milk and hot water.
Although some allowance is made for the natural vitamin content of the ingredients used, most of the vitamins are added to the formula. The Codex Alimentarius Commission (FAO/WHO, 1994) have published an advisory list of mineral salts and vitamin compounds which can be added to formulas. Predetermined excesses of vitamins have to be added to allow for processing and storage losses. UHT processing followed by aseptic packaging has been preferred to in-can sterilisation since less nutrient losses occur in the former case. Losses have been noted particularly for vitamin C, thiamine, folic acid and vitamin B6 (Hurrell et al., 1989b).
Iron absorption from formulas has been reported to be 5-10% compared to 50% for human milk. It has been suggested that bovine milk proteins or elevated calcium and phosphorus levels account for this difference. Zinc levels in formulas are also higher than in human milk to make up for reduced bioavailability.
3.1 Thermal Processes
3.2 Packaging Materials
3.3 Irradiation and Microwaves
In order to achieve the required level of nutrients in fortified products reaching the consumer, manufacturers have to estimate processing and storage losses and add the necessary excess during production. The introduction of new processes, equipment and packaging materials can affect processing and storage losses and hence fortification procedures.
Thermal treatments in food processing serve multiple functions: destruction of microorganisms, inactivation of enzymes and toxic factors, modification of flavour and texture. In many cases the heat treatment is selected based on consideration of the required lethality of the process so as to render the product safe under stated conditions of storage.
The lethality of a process is a function of both temperature and time of exposure at each temperature. The Arhenius activation energy of spore inactivation is high as compared with that for vitamin destruction. For this reason, at high temperatures the microbiological requirements of the thermal process can be met with relatively low losses of vitamin being incurred. Heat treatments based on the principle of 'High Temperature Short Time' (HTST) or Ultra High Temperature (UHT) are less destructive to the vitamin content and require the addition of lower levels of excess vitamins to account for processing losses.
As the lethality of a process is determined by sum of lethal effects at the 'cold spot' of the product unit (can, pouch, etc.), innovations in equipment design which lead to the faster attainment of thermal equilibrium will also affect the thermal process which must be delivered and hence vitamin loss during processing. The introduction of agitating retorts and retorts which can be used in the sterilisation of materials in flexible packages as well as the development of flame sterilisation processes also can have an affect on fortification procedures.
The use of retort pouches and other deformable containers in thermal processing influence processing procedures and the extent of thermal degradation of nutrients. The important role of packaging in the application of aseptic processing technologies has important implications for fortification procedures. This is not only in terms of the UHT treatments which can be applied to thin liquid films prior to packaging, but also to the impact on storage losses. The shelf life of aseptically processed foods can exceed 1 year and storage losses over this entire period must be taken into consideration in the calculation of required overages. During aseptic processes the product is cooled prior to packaging into sterile containers, headspace oxygen and dissolved oxygen levels are therefore higher than for hot-filled products or for traditional thermal processes which involve exhausting or vacuum sealing prior to processing. Problems of vitamin loss in aseptically processed foods have been attributed to dissolved and headspace oxygen, oxygen and light permeability of the packaging material and to commodity-specific reaction which are only dependent on storage temperature (Ryley and Kajda, 1994). In aseptically processed milk the dissolved and headspace oxygen lead to rapid initial losses of vitamin C activity. This in turn causes substantial losses in folate as vitamin C plays an important role in the protection of folate. Oamen (1989) also reported heavy losses of vitamins B6, and B12 during storage of aseptically processed milk.
Improvements in the barrier properties of plastics and laminates also impact on the potential for nutrient loss on storage of products other than those aseptically processed.
Irradiation is used to a limited extent in food processing and as such cannot be expected to impact upon fortification procedures to a large extent. One common use of food irradiation is in the prevention of insect infestation in grains. Losses of vitamin B1 on irradiation of whole grains are small, but increase in the irradiation of milled grains. Losses of this vitamin can be reduced by exclusion of oxygen during irradiation and storage (Kilcast, 1994).
The increased use of microwave cooking on sous-vide and other cook-chill foods does not have a major effect on vitamin retention (Hill. 1994).
4.1 Properties of Micronutrient Compounds
4.2 Other considerations in the use of fortificant compounds
Prudent handling of vitamin and mineral additives in food processing requires a sound understanding of the characteristics of these compounds: their stabilities to various unit operations, solubilities and reactivities with other compounds. Many forms of these nutrients have been developed to render them more suitable for use under a wide range of applications.
4.1.1 Vitamin A
4.1.2 Vitamin D
4.1.3 Vitamin E
4.1.4 Vitamins of the B Complex
4.1.5 Vitamin C
4.1.6 Iron fortificants
4.1.7 Iodine compounds
4.1.8 Other mineral additives
In vivo, this vitamin is generally found as the free alcohol or esterified with a fatty acid. The vitamin is available in pure form by chemical synthesis as vitamin A palmitate or the acetate, or recovered from molecularly recovered fish oil. It is a yellowish oily material which may crystallise into needlelike crystals (Parman and Salinard, 1981). Provitamins which are then converted to their active form, serve not only as nutrifyng compounds but also as colourants and anti-oxidants. The most common of these is beta-carotene.
Vitamin A is quite stable when heated to moderate temperatures in the absence of oxygen and light. Overall loss of activity during anaerobic heating may range from 5-50%, depending on time, temperature and nature of the carotenoids (Tannenbaum et al. 1987). In the presence of oxygen and light, there can be extensive loss of vitamin A activity through oxidation (Table 1). The presence of trace metals accelerates this reaction.
In dehydrated foods, vitamin A and provitamin A are highly susceptible to loss by oxidation (Labuza et al., 1978). The extent of this loss depends on the severity of the drying process, protection provided by packaging materials and conditions of storage. Vitamin A in pure form is unstable in the presence of mineral acids but stable in the presence of alkali.
Naturally occurring vitamin A is insoluble in water but soluble in oil. In this form the vitamin has limited applicability. Vitamin A fortificants are commercially available in a wide range of forms adapted for use under various conditions. For use in fat or oil based foods such as margarines, oils and dairy products, vitamin A as the acetate or palmitate have been used. They are stabilised with a mixture of phenolic antioxidants or with tocopherols. For mixing with dry products, a dry form of the fortificant was required with the appropriate size and density. Encapsulation of the vitamin in a more hydrophilic coat is commonly practised in order to achieve a more water dispersable product. Two materials used in encapsulation are gum acacia and gelatin. These dry forms of the vitamin are also stabilised using tocopherols or phenolic antioxidants.
The principal forms of the vitamin are D3 and D2. They are white, crystalline fat-soluble vitamins, formed by irradiation of the appropriate sterol followed by purification procedures. These compounds are sensitive to oxygen and light, with the D3 form of the vitamin being slightly more stable. Trace metals such as Cu and Fe act as pro-oxidants.
As with vitamin A, commercially available forms include fat-soluble crystals for use in high fat content foods, and encapsulated, stabilised versions of the fortificant, suitable for use in dry products to be reconstituted with water.
As was stated for vitamin A, at the levels of water activity which exist in dehydrated foods, these fat-soluble vitamins are most susceptible to oxidative loss.
Vitamin E is a slightly viscous, pale-yellow oily liquid obtained from molecular distillation of by-products from vegetable oil refining or by chemical synthesis. The naturally occurring form of the vitamin is the d-isomer. The synthetic compound is a racemic mixture of the d and 1 isomers. The 1-isomer doesn't have the full biological activity of the d-isomer, but due to the stability of the racemic mixture and the ease of purification, the IU of vitamin E has been defined as 1 mg dl-a tocopheryl acetate.
The free alcohol form of the vitamin is highly unstable to oxidation and is therefore widely used in foods as an antioxidant to stabilise the lip id component of foods. Esterified forms of the vitamin, commonly the acetate, are much more stable. For this reason, fortificants are usually of this form. As with the other fat soluble vitamins, cold water soluble forms have been produced by encapsulation within a suitable matrix.
Vitamin B1, or thiamine, is a white crystalline solid with a characteristic yeast-like odour and a slight bitter taste. Thiamine is produced by chemical synthesis as the hydrochloride and mononitate salts. The hydrochloride is soluble to the extent of 50% in water as compared with 2.7% for the mononitrate (Bailey, 1991).
Thiamine is one of the most unstable vitamins. Its stability to heat and oxidation is greatest at a pH range of 6 and below. At higher values of pH it becomes increasingly unstable. Thiamine is susceptible to nucleophilic attack, therefore it is degraded by some mineral salts in aqueous foods.
Thiamine hydrochloride is the fortificant of choice in cases where dissolution in aqueous media is required. In most other cases the mononitrate is used due to its lower hygroscopicity. Thiamine is also commercially available in a coated form using mono- and di-glycerides of edible fatty acids.
Biotin is a white crystalline powder of low water solubility. It is generally commercially available in diluted form as the physiological requirement for this vitamin is so low. Hoffmann-La Roche sells a 1 % mixture of this vitamin with dicalcium phosphate dihydrate. Biotin is fairly stable to heat, air and light.
Vitamin B2, riboflavin, is of an intense orange colour and low water solubility. A commercially available more water soluble form of this vitamin is the sodium salt of riboflavin 5'-phosphate. Riboflavin is generally stable under most processing conditions, but is unstable in alkaline medium. It is very sensitive to light, particularly in the presence of ascorbic acid.
Pantothenic acid, is a pale yellow, viscous, hygroscopic liquid which is very unstable. The most commonly used commercially available form is calcium pantothenate. This is a slightly hygroscopic white powder with no smell but a slightly bitter taste. Stability of this compound is greatest at pH values between 5 and 7.
Vitamin B6, pyridoxine, is available commercially as the hydrochloride. Coated forms are also available as with all of the B-vitamins. This vitamin is quite stable to heat and atmospheric oxygen and heat, but degradation is catalysed by metal ions.
Niacin in the form of either nicotinic acid or nicotinamide, can be used in nutrient addition to foods. At very high levels, nicotinic acid has been shown to cause unpleasant side effects such as flushing and 'pins and needles'. This has led to some preference for nicotinamide. Both forms of the vitamin are stable to atmospheric oxygen, heat and light in the dry state as well as in solution.
Cyanocobalamin, the most important compound with vitamin B12 activity, is commercially available as a crystalline, dark red, hygroscopic powder. Human requirements for this vitamin are very low and it is commonly sold highly diluted by a carrier. In the preparations sold by Hofmann-La Roche, for instance, it can be purchased diluted with mannitol or a mixture containing modified starches, citrate, citric acid, benzoate, sorbic acid and silicon dioxide. The selection of preparation depends, of course, on the end use. In solution it is most stable between pH values 4-7. It is unstable to oxidising and reducing agents and exposure to sunlight, but is fairly stable to heat (Bailey, 1991).
Folic acid is a yellow-orange, odourless, tasteless crystalline substance. It id moderately stable to heat and atmospheric oxygen. In neutral solution it is quite stable, but instability increases with a shift in pH in either direction. Folic acid is unstable to heat, light, sunlight, oxidising and reducing agents.
Vitamin C or ascorbic acid is an odourless, white, crystalline compound which is stable in its dry form. Due to its high water solubility, losses due to leaching can be a problem in some processing procedures. Ascorbic acid is readily oxidised. In dehydrated citrus juices the degradation is dependant on both temperature and water activity. Other factors as well can influence the degradation behaviour of vitamin C, these include salt and sugar concentration, pH, oxygen, metal catalysts and ratio of ascorbic: dehydroascorbic acid.
Vitamin C addition to foods is commonly practised for reasons other than fortification. Commercially available forms of this vitamin include the free acid and the sodium and calcium salts of these, in powder as well as crystalline or granular form. For mixing with dry products, particle size and density are of course important considerations. A fat coated form of ascorbic acid is also available for enrichment purposes. Ascorbyl palmitate, is a form of the vitamin used for purposes other than fortification. It is used as an antioxidant in fats and oils and has also emulsifying properties (Anon. 1985). Other areas of food processing for which vitamin C has application are the prevention of browning in fresh and canned fruit and vegetables, acidification, curing of meat and prevention of haze formation in brewed products (Borenstein, 1987).
Iron compounds used in food fortification are commonly classified according to their solubility. Selection of an appropriate iron fortificant for any given application is based on the following criteria: organoleptic considerations, bioavailability, cost and safety (Hurrell and Cook, 1990).
The colour of iron compounds is often a critical factor when fortifying light coloured foods. For example white iron, ferric orthophosphate, is often the fortificant of choice in the enrichment of rice.
The use of more soluble iron compounds often leads to the development of off-colours and off-flavours due to reactions with other components of the food material. Infant cereals have been found to turn grey or green on addition of ferrous sulphate. Off-flavours can be the result of lipid oxidation catalysed by iron. The iron compounds themselves may contribute to a metallic flavour. Some of these undesirable interactions with the food matrix can be avoided by coating the fortificant with hydrogenated oils or ethyl cellulose.
Bioavailability of iron compounds is normally stated relative to a ferrous sulphate standard. The highly water soluble iron compounds have superior bioavailability. Bioavailability of the insoluble or very poorly soluble iron compounds can be improved by reducing particle size. Unfortunately this is accompanied by increased reactivity in deteriorative processes.
Sodium iron EDTA is less well absorbed than ferrous sulphate from foods which contain few inhibitors to absorption. In the presence of these inhibitors, however, the EDTA complex is better absorbed. Sodium iron EDTA also participates to a lesser extent in deteriorative reactions. The use of this compound reduces the problem of precipitate formation in foods such as fish sauces and tea. The use of this compound is not advised in developed countries where the population already receives close to the recommended acceptable daily intake of EDTA (Hurrell and Cook, 1990).
The problem of low bioavailability of some of the less reactive forms of iron is often circumvented by the use of absorption enhancers added along with the fortificant. Examples of such enhancers are ascorbic acid, sodium acid sulphate and orthophosphoric acid.
The most commonly used compounds in the iodisation of foods are the iodides and iodates of sodium and potassium. These are the additives allowed by Codex Alimentarius in the iodisation of salt. The iodide compounds (Bauernfeind, 1991) are cheaper, more soluble and have a higher iodine content (so that less is needed to achieve the same level of iodisation) than the corresponding iodates. Iodates are more stable under conditions of high moisture, high ambient temperature, sunlight, aeration and the presence of impurities. The use of iodate is therefore recommended for use in developing countries. Potassium iodide is well suited in cases where the salt is dry, free from impurities and has a slightly alkaline pH. Otherwise the iodide may be oxidised to molecular iodine and lost through evaporation. If excess water is present the iodide may be separated from the salt in the water film (FAO/WHO, 1991). Loss of iodide can be reduced through the addition of stabilisers such as 0.1% sodium thiosulphate and 0.1% calcium hydroxide combined or 0.04% dextrose and 0.006% sodium bicarbonate (Kuhajek and Fiedelman, 1973). Calcium salts have been used with some report of off-flavour due to the calcium ions (Kuhajek and Fiedelman, 1973). The calcium compound is also much less water soluble than the sodium and potassium compounds and this further limits its applicability.
A range of mineral salts are available for fortification with Ca, Mg, P, Zn, Cu and Mn. Prudent selection of mineral compounds is based largely on consideration of mineral reactivity and solubility of the salt. The requirements of the fortificant vary according to the nature of the food product and its end use. To overcome problems of flavour, texture and colour deterioration due to addition of minerals, some companies have engineered new fortificant preparations which generally involve the use of stabilisers and emulsifiers to maintain the mineral in solution (Anon. 1986).
4.2.1 Bioavailability of commercial preparations
4.2.2 Nutrient-nutrient interactions
4.2.3 Nutrient-matrix interactions
While the practice of coating many of the water soluble vitamins does offer protection against interaction with the food medium and development of organoleptic problems, it can create other difficulties. Slow dissolution of the coating in the gastrointestinal tract in order to free the active component can cause reduced bioavailability of the micronutrient (Borenstein et al., 1988). Care should therefore be taken in the use of such preparations that the nutritional objectives are being met.
When more than one fortificant is being added to a particular vehicle, consideration must be given to the interactions, both positive and negative, which could take place. An example of this is seen with vitamin C and iron (Johnson, 1994). Vitamin C has been shown to improve the absorption of iron (Cook and Rueser, 1983; Hurrel and Cook, 1990). Other studies have indicated that iron and other trace metals increase the rate of ascorbic acid destruction (Dennison and Kirk, 1982). This deteriorative reaction was dependent on their being sufficient moisture to facilitate the mobility of the metal ions and was therefore demonstrated not to be a factor at water activity levels below 0.4.
The presence of vitamin E has been shown to increase the bioavailability of vitamin A, one explanation of this is that tocopherol as a lipid phase antioxidant, stabilises vitamin A in the GI tract (Borenstein et al., 1988). Calcium has also demonstrated an inhibitory effect on iron absorption (Hallberg et al., 1992). Phosphorous negatively influences calcium absorption and due to this fact, calcium/osteoporosis claims can only be made in the United States if the calcium: phosphorous ratio is greater than 1:1 (Anon., 1993).
In solution, ascorbic acid has been shown to destabilise folic acid and cyanocobalamin (Ottaway, 1993). Ryley and Kajda (1994) reported that vitamin C in UHT milk played an important role in the protection of the folate content. Degradation products of thiamine have also been shown to accelerate the rates of degradation of folic acid and cyanocobalamine, whereas the presence of iron salts in solution reportedly have a stabilising effect on cyanocobalamin (Bailey, 1991). In solutions of the B-vitamins, riboflavin can cause the oxidation and consequent loss of thiamine. If ascorbic acid is included into the solution the reaction does not occur (Ottaway, 1993). This observation is of practical significance in cases where solutions of water soluble vitamins are sprayed onto foods during the fortification process. Riboflavin also promotes oxidative degradation of folic acid, but this effect can be minimised by deaeration. Riboflavin has also been implicated in oxidative loss of vitamin C. Light-induced vitamin C loss from milk is reduced in the absence of riboflavin (Ottaway, 1993).
Besides nutrient - nutrient interactions, other components of the food matrix may also affect the functionality of the fortificant. Selection of the vehicle in fortification programmes much be such as to avoid reduced bioavailability of nutrients due to the presence of anti-nutritional compounds. Some interactions of added nutrients with the food matrix have been noted but are poorly understood. For example, the absorption of iron from sugar fortified with ferric orthophosphate and ascorbic acid was shown to be greatly improved when added to maize porridge before cooking as compared with after cooking (Disler et al. 1975).
Ascorbic acid is involved in many browning reactions (Davies and Wedzicha, 1994). Vitamin B6 B can take part in the maillard browning reactions under suitable conditions and thiamine can react with polyunsaturated fatty acids to produce a typical 'meaty' flavour and odour. Owing to such interactions, most of the water soluble vitamins are commercially available in coated form. The use of these coatings may be associated with problems of bioavailability (Section 3.8.1).
lodisation of salt and the compounds used for this have been widely studied in relation to the stability of the fortified salt. More research may be required if iodisation of processed foods through the use of iodised salt is to be widely practised. The available information on this topic has shown no problems with off-flavour and off-colour development in many common processing applications such as vegetable fermentation (Kosima and Brown, 1955), production of fresh pack pickles (Breed and Kendall, 1970) and canning of vegetables (Breed and Kendall, 1970; Kuhajek and Fiedelman, 1973). In some specific cases, however, the use of iodised salt might be problematic. Off-flavour development in a cake mix was shown to be due to the use of iodised salt in its manufacture (Sevenants and Sanders, 1987). There also needs to be more information on the stability of iodised salt under conditions experienced in vegetable fermentations.
5.1 Quality Assurance/Control in Food Processing
5.2 HACCP and QACCP
5.3 Analysis of Vitamins and Minerals
5.4 Role of Legislation and Food Control
The maintenance of a well functioning Quality Assurance (QA) programme is essential if a consistent product is to result which meets all required standards. Such a programme should be based on Hazard Analysis and Quality Analysis Critical Control Point (HACCP and QACCP) systems. HACCP and QACCP are more proactive than traditional approaches to QA/QC activities. The establishment of such programmes is the responsibility of QA personnel but the execution of it involves everyone in the company. To avoid ambiguity regarding responsibility for any QA function, it is important to assign specific HACCP/QACCP accountabilities to responsible persons and groups (Corlett, 1992).
A QA programme must consider all activities impacting upon product quality, from raw materials and ingredients used to product handling through distribution channels all the way to the final consumer. In respect of this, Wilson (1991) has outlined the following required components of a QA system:
i) Raw material control - standard specifications must be adopted for all ingredients which must then be inspected to ensure conformity;
ii) Process control - all chemical, physical and microbiological hazards as well as quality factors must be identified, critical control points (CCP) must be established, monitored and a record made of any action taken;
iii) Finished product control - this requires that the finished product be unadulterated, properly labelled and that the integrity of the finished be protected from the environment.
All food production activities must be monitored and controlled within the framework of an effective QA programme. The addition of nutrients to a food for the purpose of fortification adds to the control points which have to be considered. Poor manufacturing control leading to excessively high levels of nutrients in the finished product could have important health implications for the consumer if intake of the nutrient reaches the toxic dose. Conversely, low levels of nutrients in the finished product could render it nutritionally ineffective. This could also have serious health implications if the target population in the fortification programme was at high nutritional risk. Poor manufacturing control could also lead to other quality defects related to interactions of added nutrients with other components of the system.
The following steps in the implementation of a quality assurance programme in the production of a fortified food have been outlined by Wilson (1991):
i) Product specifications - All specifications for fortificants, food vehicle and any other ingredients must be documented as well as acceptable deviations of these. These include specification of particle size, colour, potency, level of fortification as well as any other requirement which might be deemed necessary.
ii) Product safety assessment - This involves an assessment of microbiological, chemical and physical hazards for all ingredients and the finished product
iii) Product analysis - Sampling and testing procedures for all ingredients and the finished product must be explicitly stated.
iv) Determination of critical and quality control points - Based on first hand knowledge of the total process (including the plant facility, equipment and environment) stages at which inadequate control could lead to unacceptable health risk or adversely affect product quality are identified. The system of controls and actions to be taken at each control point are documented.
v) Recall system - A mechanism must be put in place whereby product can be recalled if such action becomes necessary.
vi) QA audit - Periodic checks are necessary to verify that the QA system is effective and product quality is maintained up to the ultimate consumer.
vii) Feedback mechanism - Response to consumers and other relevant groups to correct any deficiencies discovered.
viii) Documentation of QA system - Details of the QA programme used in the production of the fortified food must be readily available to relevant individuals and organizations.
Shortcomings of many fortification programmes in the past have been due to failure to establish an adequate quality assurance programme. Evaluation of the fortification of sugar with vitamin A in Guatemala showed that only 30% of samples tested were fortified at levels within the legal limits (Nestel, 1993). A study of iodine content in iodised salt samples obtained from several plants in India also provided an example of the need for greater control in processing (Ranganathan and Narasinga, 1986).
In the determination of critical and other control points for any process accurate flow diagrams outlining the total process have been used (Pierson and Corlett, 1992). The construction of an accurate flow diagram for any given process requires first hand knowledge of the processing facility and its environs so that all factors which might be expected to impact on product safety could be identified. Annex 1 includes a list of common critical control points and examples of monitoring procedures in the processing of selected fortified foods, which are intended to demonstrate the main points of a quality assurance programme.
Recommendations of the FAO/WHO Expert Technical Consultation on "The Use of HACCP in Food Control' (1995c) included the following:
i. Use of HACCP serves to improve food safety control and should be applied on that basis;
ii. The elaboration of food safety policies by government and international agencies should use risk analysis as the basis for establishing food safety priorities and for focusing inspection resources. These policies should be implemented through national strategic plans;
iii. In the post Uruguay Round of GATT, the Codex Alimentarius Commission should recognise the importance of its role in harmonising and establishing food standards, guidelines and recommendations particularly as it relates to safety of food in international trade. Codex should develop a strategic plan which will include a strengthening of the scientific basis for risk analysis, equivalence and the elaboration of its standards, guidelines and other recommendations and should include specific instructions to the Codex Committees on incorporating HACCP.
Analysis of potency of fortificants and of vitamin and mineral content constitute an important component of the overall analytical requirements in QA/QC programmes for fortification processes. Development or selection of appropriate analytical methodologies must be based on consideration of accuracy and precision of measurements, available facilities and equipment, simplicity of procedure and rapidity of determination.
A list of relevant Codex Alimentarius reference methods are summarised in Table 2. There are also many other experimental methods which have been developed in various laboratories. The Codex Committee on Methods of Analysis and Sampling is working in close cooperation with ISO, AOAC International and IUPAC to recommend protocols for determining the reliability of analytical test methods and results of laboratory analyses (FAO/WHO 1995d). The community bureau of reference of the Commission of European Communities (BCR) has set up a working group to compare analytical methods used in different laboratories in Europe. Walter (1994) summarised the methods most commonly applied to the analysis of vitamins in foods. HPLC is the technique of choice for many of the vitamins because of the reliability of the method, the rapidity of the determination and the often reduced requirement for rigorous preliminary clean up steps. The drawbacks associated with this technology, however, are high equipment and materials costs and its lack of mobility. A comprehensive review of current methods used in the analysis of vitamins was provided by Lumely (1993).
For analysis of vitamin A content in the MSG fortification programme Muhilal et al. (1986) developed a quantitative spectrophotometric method. A semi-quantitative method was also described suitable for field testing in the MSG-vitamin A programme. A rapid quantitative method for the determination of vitamin A content in fortified sugar has been described by Aguilar et al. (1977). This is based on the Carr-Price procedure. Adaptations of the method, yielding semi-quantitative results, suitable for field testing have also been reported (Arroyave et al., 1979).
The determination of iodine content in iodised salt has traditionally been carried out using a titrimetric method. Recently a number of HPLC based methods have been used to a large extent. One such method described by de Kleijn (1983) was used by the Food Inspection Service in the Netherlands. It utilised reversed phase HPLC with uv detection, and had a detection limit of 2.9 ng KI. Modified HPLC procedures involving precolumn derivatisation have been developed to increase the sensitivity of the analysis. In this way Verma et al. (1992) reported a detection limit of 0.5 ng iodide. Another recent report involved a differential pulse polarographic method which did not require a separation or preconcentration step (Daneshwar et al., 1987). For qualitative testing in the field, simple test kits based on the reaction of starch with iodine are available (Anon, 1995). There are important restrictions to the use of the kits which are currently being used. These are reported to be applicable over a restricted pH range. Additives commonly used in salt such free-flowing agents or stabilisers of added iodine cause the pH to be elevated above the valid range. In such cases, false negative results are obtained. Modification of this procedure to extend the functional range of testing conditions must be investigated. Users of such field kits need to be educated as to their correct use and their limitations.
In iron fortification programmes, quite often measurement of iron content is inadequate. Bioavailability of the nutrients has been determined by measurement of labelled isotopes absorbed from the diet of human subjects or less complex methods based on animal studies such as the haemoglobin repletion method. Simple chemical methods have been used to approximate bioavailability (Bjorn-Rasmussen et al., 1977).
There may be analyses other than the measurement of nutrient content or availability necessitated by a fortification programme. These might include the measurement of colour, particle size or moisture content as well as all testing required for the unfortified food. Based on the identification of critical and other control points, the analytical requirements of the overall quality assurance programme can be determined.
The primary purposes of food legislation are to protect the health of the consumer and to protect the consumer from fraud. In the case of fortified foods, there is a need to ensure that the population is not at risk of receiving toxic doses of any micronutrient. Food laws must also ensure that the target population does not receive nutritionally ineffective levels of micronutrients. Procedures for monitoring premises where fortified foods are prepared, packed, stored or held for sale as well as mechanisms for penalising defaulters must be clearly defined within the food regulations. In Switzerland (Walter, 1994) samples of fortified products, both local and imported, are taken from the market annually for analysis of vitamin content by two specialised institutes. If vitamin content is found to be outside of established acceptable limits, the official government agency can disallow sale of the product.
Standards for fortified foods and labelling requirements must also be contained within the food regulations. Standards play an important role in the facilitation of trade, both nationally and internationally. When large differences exist between national standards, however, they can forn technical barriers to trade. In light of the Agreement on Technical Barriers to Trade, the development of international standards for fortified foods is an important step in the elimination of technical barriers.
It has been found that food law is managed most effectively in two parts: a basic food act and food regulations. The act itself should set out broad principles while the regulations should contain the detailed provisions governing the different categories of products. Within the regulations should be found lists of approved fortificant compounds and food standards stating the allowed levels of nutrients in the fortified foods. This organization gives some flexibility to food law as it is much more difficult to have laws amended than to revise regulations. Prompt revision of regulations may become necessary because of new scientific knowledge, changes in new processing technology or emergencies requiring quick action to protect the public health. With respect to regulations dealing with fortified foods, changes might be prompted as a result of safety evaluations on nutrient compounds or new information regarding the roles and optimal levels of specific micronutrients in the maintenance of good health. Changes in food processing and packaging technologies could be shown to result in a significant reduction in processing and storage losses of micronutrients, thus requiring a revision in the allowed levels of addition of nutrients. In the face of demonstrated micronutrient deficiencies, regulations regarding standards for certain foods and levels of fortification may need to be revised.
6.1 Technical Problems Requiring Attention
6.2 Analytical Considerations
6.3 Health Implications of Micronutrients
6.4 Nutritional Implications of New Dietary Trends
6.5 Standardisation and Regulation
Loss of vitamin A on storage was found to be significant in a number of fortification processes. The solution to this problem might lie in the design of a new fortificant preparation in which vitamin activity is better protected. This approach has, however, in the past led to new problems regarding cost and bioavailability. Alternatively more studies might be carried out to determine critical factors pertaining to packaging materials or storage conditions which affect vitamin content.
Problems persist with iron fortification as well. Discolouration of the food vehicle due to the presence of iron hinders consumer acceptance in many cases. With the existing iron fortificants available commercially, trade-offs with respect to reactivity, bioavailability and cost must be accepted. Sodium ferric EDTA has several useful properties in respect of fortification, but its status as a food additive is only now being considered by Codex Alimentarius Commission for use as a dietary supplement for use in supervised food fortification programmes in populations where iron-deficiency anaemia is endemic (FAO/WHO, 1993). JECFA has requested that additional studies be carried out to assess the site of deposition of iron administered in this form.
Loss of vitamin C during storage, particularly due to the presence of oxygen, is a problem with many fortified foods. Possible solutions to this problem include the development of new, more highly protected vitamin fortificants or investigation of new packaging materials or storage conditions which promote increased vitamin stability.
The use of iodised salt in food processing is another area which requires attention. There are at least two distinct issues to be considered: the first is the role of iodine compounds in deteriorative reactions such as off-flavour development and discolouration, the second is the effect of processing operations on the iodine content of the fortified food. Some relevant data for selected food processes have been reported (Wirth and Keuhne, 1991a and b) but further research needs to be done. If, for example, the iodine fortification of fermented vegetable products was to be considered through the use of iodised salt in their production, it would be essential to know the effect of the iodine compound on product quality as well as the stability of the iodine compound under fermentation conditions.
Many advances have been made with respect to the analysis of micronutrients in foods. According to Walter (1994) problems still remain with the analysis of vitamins which occur in very small concentrations such as vitamins D3, B12, folate and biotin.
Research is required into the development of appropriate analytical methods for use in the field. Such testing is a required component of quality assurance in food fortification programmes. 'Appropriate' is determined by such factors as availability of equipment and materials for testing, accuracy and precision of the testing method, simplicity and rapidity of the experimental procedure.
As analytical methodologies continue to be developed or modified there is a need to verify agreement of results obtained using different procedures. There may also be a need to standardise some aspects of experimental procedures.
Fortification practices are predicated on our understanding of our physiological requirement for the micronutrients. This understanding has continued to be expanded. The possible preventative effect of antioxidative vitamins on cardiovascular disease and cancer is currently the subject of much investigation. Based on the findings of these investigations, an increase in the recommended daily allowances for these vitamins may be indicated (Walter, 1994). Since fortification procedures are based upon delivering a predetermined proportion of the RDA for the nutrients in question, such research will impact upon food fortification. Up to the present time, due to high variability between and within individuals, it has not been possible to establish generally accepted cut-off values for the health protective potential of B-carotene, vitamin E and vitamin C (Pietzrik, 1995).
RDA's and National Reference Values (NRV) for an expanding number of essential trace minerals are being determined. Continued international discussion and agreement on these is essential.
Consumer demand for low fat products has given rise to concern that the loss of fat soluble vitamins associated with the removal of fat could lead to inadequate intake of these vitamins among certain sectors of the population (Anon, 1995c).
The finding of the paper prepared by Germany for the Codex Committee on Nutrition and Foods for Special Dietary Uses was that it was premature to determine fortification requirements for lower tat products. Their recommendation was for intensive study of consumer behaviour before other measures be taken (FAO/WHO, 1995b).
A thorough review of existing legislation pertaining to fortified foods needs to be carried out. This should provide the basis for suggested changes where it is found necessary. An example of the effect of legislation on fortification procedures was the use of a mixture of table salt and curing salt in the production of certain iodised sausages in Germany since iodine was allowed in table salt but not curing salt (Wirth and Kuhne, 1991).
The General Agreement on Tariffs and Trade (GATT) Uruguay Round of Multilateral Trade Negotiations have had significant implications for the work of the Codex Alimentarius Commission. The GATT Agreements on the Application of Sanitary and Phytosanitary Measures and on Technical Barriers to Trade emphasize the need for international standards, guidelines and recommendations to facilitate international trade (Byron, 1993). The Codex Alimentarius Commission needs to work further on the development of standards for fortified foods. Such standards must of course be consistent with the general principles of the Commission regarding fortification. International standards must be sufficiently flexible to allow national governments to meet the specific nutritional needs of target populations while still providing guidance with respect to acceptable ranges of fortification and unambiguous definition of terms.
International standards for fortified foods used in food aid programmes need to be considered. This would facilitate the interchangeable use of foods coming from different sources in meeting the needs of target groups (Nestel, 1993; Combs et al., 1994), and could provide the standard which quality assurance programmes should demonstrate all food aid products to meet.
Fortification of foods can be a useful tool in combatting micronutrient deficiencies. Its effectiveness depends on the skill and experience with which it is applied. It is not the appropriate tool in all situations and generally speaking, its use is required in combination with other techniques in order to obtain the optimal result. It is critical to identify all elements underlying any given nutritional problem: food security; inadequate dietary diversity; lack of nutrition education and the state of food processing locally are among the factors which must be considered in determining the most appropriate strategy to be used and hence role to be played by fortification.
The successful application of food fortification technology is based largely on consideration of the compatibility of vehicle, fortificant and process. Scientific and engineering advances have resulted in an increasing number of options regarding choice of fortificant compound and processing procedures. This has resulted in the improvement of food fortification technologies used for a range of products. It is important to realise that there is a limit to the possibilities of new technologies for example, multiple fortification of certain food vehicles may result in substantially increased cost and reduced bioavailability.
Adequate quality control of food fortification processes has often been overlooked in the past. If this practice continues it will not be possible to realise the benefits potentiated by upgraded technologies.
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1377-1380, 1382-1384, 1432.
Vitamin A enriched MSG
(GMP-Health and Welfare Canada)
Critical Control Point
Receiving of raw ingredients
Each lot of purchased raw ingredient should be tested by approved methods to confirm compliance with specifications unless the manufacturer has records to show that the raw ingredient is consistently within specifications. There should be an ongoing programme to ensure the continuing reliability of each vendor.
Production of premix
Quantitative analyses should be carried out for each component in each batch of any bulk vitamin or mineral premixes manufactured 'in-house'.
Storage of premix
Vitamins and premixes should be reassayed for potency every three months to ensure that they continue to meet the required potency up to the end of their shelf-lives; or well documented data should be available to show that the above frequency of testing is not necessary.
Addition of vitamins or premix
Each weighing and/or addition of vitamins or premix should be initialled by the employee involved and the sheet checked and initialled by the supervisor.
Critical stages of the manufacturing process should be monitored in such a way as to ensure that no unexpected nutrient losses ocurr during processing or after unpredictable delays. Monitor recording charts of time/temperature history during thermal processing or during drying.
Inventory control should be maintained on all raw materials by weighing, daily, the remainder of those raw materials which were utilised in the day's production.
Finished product control
Each lot should be sampled and tested for compliance with its chemical, microbiological and physical specifications prior to release by the QA/QC department. Testing for each lot should include analysis for protein and all added vitamins and minerals.
Critical Control Point
Receipt of raw materials
Each lot of a purchased raw ingredient should be tested by approved methods to confirm compliance with specifications.
Storage of vitamins/minerals
Monitor storage conditions to ensure that manufacturers' instructions are followed.
Addition of vitamins/minerals
Keep a permanent record of calculations for vitamin/mineral additions to the finished product to demonstrate whether additions theoretically give the correct range.
Regular testing and recording of the in-line accuracy of the metering pump.
Make a visual check every 1-2 hours to make certain that the vitamin preparation is being used up at a consistent rate and keep records of this.
Keep daily records showing actual vitamin uasge and actual flour production.
Critical Control Point
Receipt of white vitamin A
Verify that white vitamin A is being produced according to the required specifications.
Evaluate and keep records of colour, particle size and potency on arrival.
Storage of vitamin A
Monitor storage conditions in order to maintain optimal levels.
Addition of vitamin A
Weights of vitamin added should be initialled by the employee involved and checked and initialled by the supervisor.
Blending of vitamin/MSG mixture
Conditions used for mixing should be monitored and recorded. Use control charts to monitor percent variation of vitamin A in the fortified product.
Final product control
Check that blended MSG/white vitamin A potency meets specification.
Inventory control should be maintained on vitamin A and MSG by weighing, daily, the remainder of those raw materials which were utilised in the day's production.