G. Heinz
The author is Senior Officer (Meat Technology), Meat and Dairy Service, Animal Production and Health Division, FAO, Rome, Italy.
Impact of meat preservation and processing
Meat preservation and processing techniques suitable for developing countries
Hygienic slaughtering
Meat inspection
Training in meat processing and sanitary control
Prospects of meat processing in developing regions
Bibliography
The contribution of livestock to food supplies in developing countries is increasing at a higher rate than that of cereals. The total meat production in developing countries rose from 30 million tonnes in 1970 to 69 million tonnes in 1990, and it is projected to reach 105 million tonnes in the year 2000 and 143 million tonnes in 2010. Developing countries now account for almost half of the total world meat production (FAO, 1994a; FAO, 1994b). While in developed countries a certain saturation and decrease in the overall consumption of livestock products can be seen, the demand for livestock products will continue to rise in developing countries as a result of their rapidly expanding populations and the tendency towards higher incomes in most of these countries.
In contrast to developed countries, where the high consumer intake of livestock products has contributed to health problems, the predicted increase in consumption patterns in developing countries over the next few years will be beneficial to the nutritional and health status of the majority of their populations. Together with fish, livestock food products provide essential amino acids, minerals and vitamins in a concentrated form, and their fat content can also supply much needed calories. Meat is particulary important in the diets of young children and pregnant women because of its high protein and iron content.
In spite of the increasing levels of livestock production in most developing countries, the proportion of meat in the diet of the average consumer remains rather low. This is mainly because the human population grows almost as fast as that of livestock (in Africa it grows even faster), but also because meat is scarce in many places and its cost is comparatively high.
The supply shortage of livestock products in certain areas in developing countries is a consequence of the traditional marketing systems, where fresh, unprocessed meat is sold at meat markets a few hours after slaughter. These systems are used in all the developing regions where no cold chain for refrigeration exists.
Although livestock is raised in rural areas, meat is frequently not available there, since the slaughtering takes place in central abattoirs in urban areas. Cost also limits the consumption of livestock products. In many developing countries, the average daily income is equivalent to the price of 1 kg of meat. It is therefore not surprising that many consumers can only occasionally afford livestock products and they are consequently not part of the everyday diet. The average annual per caput consumption of meat is 20 kg, compared with 80 kg in developed countries. The latter is calculated on the basis of carcasses (with bones) and edible offal. In the poorest countries, the annual rate of meat consumption per caput is as low as 5 kg. In actual fact, the consumption patterns of most populations are probably even less, since the average figures also include the higher income groups with atypically high consumption. It is therefore clear that a greater consumption of livestock products would be highly desirable in developing countries.
The following examples illustrate the benefits of a higher intake of livestock products in developing countries:
· For adequate nutrition, a person's daily protein intake should be 1 g per kilogram of body weight. In developed countries this is easily reached and, in most cases, exceeded, while in developing countries there is a widespread deficit. Ideally, 30 to 50 percent of the daily protein intake should be animal protein, particularly in developing countries, since this provides an optimal range of amino acids. The average intake of animal protein in developing countries, however, is as low as 15 g per person per day (10 g from meat and 5 g from milk), compared with almost 60 g in developed countries.· With regard to minerals, meat is one of the most important sources of iron. In developing countries anaemia caused by lack of iron is one of the major nutritional problems, particularly in young women and children. The other important livestock food, milk, is the most important source of calcium in human nutrition. It can also be used as an additive in processed meat products.
With regard to providing consumers with adequate quantities of quality meat and meat products, one aspect is becoming increasingly important, namely, the processing of products based on meat as a raw material. Appropriate processing techniques offer the opportunity of overcoming the two main constraints to a better supply of livestock products - availability and price (FAO, 1994c).
Shelf-stability
Using specific processing techniques, it is possible to produce shelf-stable meat products that can be stored under ambient temperatures, eliminating the limitations of the traditional livestock-products marketing system. In the traditional system, pressure is put on producers and consumers to complete the cycle from procurement to consumption of livestock products in a very short period, in most cases, within one day.
In contrast, in prolonged distribution chains for livestock products, which will be increasingly evident in the rapidly expanding population centres in all developing regions, not only can shelf-stable livestock products be handled safely, but their supply to consumers in rural areas far from food processing plants and abattoirs will be ensured.
Affordability
Meat processing can also tackle the price problems of meat products, while at the same time allowing the raw materials, such as carcass meat and by-products, to be classified as valuable and less-valuable products. The parts that are graded "less valuable" because of poorer censorial properties such as taste and tenderness, may be very valuable from the nutritional and processing point of view. This is the case with meat derived from the head, lower parts of the legs, the diaphragm and internal organs. These parts can be used for processed meat products. It is obvious, therefore, that good-quality products can be produced with cheaper raw materials, while the more expensive carcass parts can be profitably sold to customers who can afford higher-priced meat or meat products (FAO, 1995).
Prices for meat products can be further decreased by using meat extenders, which may include plant or crop products such as flour and starches. Dairy products and fish, which can partially replace expensive meat while keeping the products at an adequate level of nutritional quality, may also be used (Karmas, 1976) (Figures 1 and 2).
Tables 1 and 2 list meat preservation and meat processing methods that are already practiced to a certain extent in some developing regions or that will be of increasing importance in order to supply the expanding populations with sufficient quantities of good-quality and affordable meat products.
It should be noted that, in many cases, the preservation and processing technologies mentioned are not applied as a single treatment, but rather one treatment method may follow another or a combination of treatments may be used.
Intermediate moisture meats
The evaporation of water or the replacement of part of the meat (which contains 80 percent water) with non-meat additives can often help to extend the shelf-life of a product. The substitution of meat with plant products or other meat extenders decreases the water content of the meat products, or, expressed in scientific terms, the water activity in the product. The product's microbiological stability increases when less water is present for microbiological growth.
1 Meat preservation methods - Méthodes de conservation de la viande - Métodos de conservación de la carne
|
Method |
Basic technologies |
Main effects |
|
Lowering the moisture content (reduction of water activity aw) |
Evaporation of product water by drying or replacement of water by other food additives |
Control of microbial growth (inhibition or cessation of growth depending on the type of microorganism) |
|
Increasing the acidity |
Lactic acid fermentation or addition of organic acids |
Inhibition of growth of spoilage and food- poisoning microorganisms |
|
Preservative effects of treatment or meat additives |
Salting, curing or smoking; suitable preservative |
Inhibition of growth of spoilage and food-poisoning microorganisms |
|
Thermal treatment |
Boiling, cooking or roasting |
Significant reduction of most microorganisms, but recontamination is unavoidable as product is not hermetically sealed |
|
Thermal treatment in hermetically sealed containers(cans, glass jars, synthetic containers) |
Pasteurization, sterilization |
Reduction of bacterial counts and enzyme activities by heat; no recontamination |
2. Meat processing methods - Méthodes de traitement de la viande - Métodos de elaboración de la carne
|
Method |
Products |
|
Carcass dressing at the abattoir level |
Dressed whole carcasses, carcass sides or quarters Edible animal by-products (internal organs) |
|
Carcass/meat cutting |
Wholesale and retail meat cuts for frying, cooking, roasting, etc.; meat for further processing |
|
Drying of unsalted pieces of meat |
Dried meat for preparation of meat dishes |
|
Salting and curing of meat cuts with or without heat treatment |
Cooked ham, cooked cured beef, bacon, raw ham and other raw cured products such as dried cured products |
|
Coarse comminuting of raw meat |
Hamburger-type products |
|
Coarse or fine comminuting of raw meat with subsequent fermentation |
Fermented sausages of the salami type, fermented Asian products (e.g. naem) |
|
Fine comminuting of raw meat with subsequent heat treatment |
Emulsion-type sat/sages, e.g. frankfurters, meatballs, emulsion type meat pies |
|
Fine comminuting of precooked meat together with internal organs, blood, etc. |
Liver paté, liver sausage, blood sat/sage, meat pies. |
The technical term for food products with reduced water activity is intermediate moisture (IM) foods. All empirical meat preservation methods based on the drying of the meat or meat products fall into this category. Drying can either be done alone or in combination with other methods such as salting, curing or smoking. Meat drying techniques have been used for centuries and can be considered the oldest meat preservation methods (FAO, 1990; FAO, 1993) (Figure 3).
Meat drying is simply the exposure of strips or flat pieces of fresh meat to the sun or open air. This treatment reduces the meat's water content so rapidly that no bacterial spoilage can take place, even though the temperatures remain high. There are certain disadvantages with this simple drying method, however, including contamination by insects, dust and other environmental impacts. Cabinet solar dryers have been especially developed for this purpose, where warm air is conducted through a hermetically closed chamber, thereby avoiding any undesirable impacts from the outside. So far no source of energy other than the sun has been used in solar drying methods (FAO, 1993; FAO, 1994d).
FAO is in the process of implementing a project in Ghana that will compare the empirical solar cabinet drying method with a modified technique, the solar tunnel drying method. Solar tunnel drying is a more sophisticated approach, where high energy inputs from the sun are achieved through a long solar collector ("tunnel") using electric fans. In areas without electricity, these fans can also be run by using photovoltaic panels to convert solar energy directly into electricity. The construction materials for the solar tunnel dryer are relatively cheap and simple and can be produced locally. This drying method is expected to be a major step forward towards hygienically, technically and economically efficient meat drying, also on a semi-industrial scale if the daily throughput is high enough. The method is absolutely clean and has no negative impact on the environment.
Of course, this improvement of the drying methods must be accompanied by improvements in the pretreatment of fresh meat and in the packaging and storage of dried meat. Different pre-treatment methods, such as selecting specific carcass parts, salting, curing and smoking, will be tested, as will traditional and modern packaging materials such as vacuum bags.
The greatest variety of dried meat products can be found in Africa. Besides the common dried meat strips or flat pieces, there are many different product preparations and names (Table 3). In Latin America, particularly in Brazil, a product called charqui has long been used to supply remote areas. Several large flat pieces of beef are salted, piled on top of each other and finally exposed to the sun for drying. A North American product is pemmican, or jerky, which is dried beef or game meat, often kept under a layer of lard for better storage. In Asia, simple meat drying, although known, is not very popular. Particularly in Southeast Asia, meat to be dried is usually pretreated, for example, it may be soaked in a salt or sugar solution (FAO, 1985; FAO, 1990).
Sugar plays an important role in meat preservation in Southeast Asia, especially for those products that have not been dried. Sugar replaces part of the product's water and makes it more stable from the microbiological point of view. Moreover, sweet-tasting meat products are very popular there. A well-known example is Chinese sausage, which contains a mixture of minced pork, fat, salt, spices and sugar filled into small casings. Stored under ambient temperatures without further treatment, the sausages are shelf-stable for a few days. Heat treatment by cooking or frying only takes place immediately prior to their consumption (FAO, 1991a) (Figure 4).
Fermented products
Other types of shelf-stable meat products are fermented products with or without simultaneous drying. Well known are the dried hams, which are non-comminuted meat parts containing salt, spices and curing agents. These are kept for a certain period of time under moderate temperatures to allow a bacterial fermentation to take place. During the fermenting process the product loses water and reaches a certain level of acidity. This combined effect makes the product shelf-stable. The dried hams are most popular in Western countries but are also found in China and Latin America.
A typical fermented product produced in South Asia is naem. These are small portions of comminuted pork and pork skin mixed with spices, particularly garlic, and traditionally wrapped in banana leaves, although today synthetic casings are commonly used. Fermentation occurs in the product and allows its storage under ambient temperatures for at least three days or longer. It is very popular and readily available for small meals or snacks and therefore has an important role in providing consumers with animal protein.
It is expected that traditional Asian meat preservation methods will play an important role in the distribution of livestock products to consumers in the future. FAO has initiated activities to evaluate and technically improve these traditional methods and disseminate them to regions where they are unknown. These processing methods are also dealt with in FAO regional training courses on meat technology so that people involved in the meat industry are aware of the advantages of these techniques.
Heat-treated products
In addition to the traditional meat preservation methods, new modern meat preservation techniques are playing an increasingly important role in meat processing in developing countries. Heat-treated products in hermetically sealed containers are one result of these new techniques. The best known of these are canned meat products, which are pasteurized or sterilized. The sterilized products can be stored under ambient temperatures for up to three or four years.
Southeast Asian countries have taken a leading role in introducing sterilized products that are different from canned products. They have adopted the Western technology of filling synthetic casings with meat mixtures, closing them hermetically and then sterilizing them. These sausages remain shelf-stable for several months. This technique is less complicated than canning, and FAO is currently cooperating with the Chinese Meat Research Institute on the development of suitable products. It is also planning to hold a regional training course on the subject.
The first fully sterilized meat product ever produced was probably "mud" or "clay" meatballs from West Africa. Pieces of meat are wrapped in banana leaves and surrounded by a layer of clay. These mud meatballs are then placed in the hot ash of open fires, where the mud layer solidifies into a hermetically sealed package with the sterilized meat inside. The shelf-life of these products is more than one year. The sensorial properties of meat processed in this way are not optima, however, and it is difficult to produce large quantities of this product. As a result, it can only provide the meat supply at the household or village level, but not for rapidly expanding populations (Figure 5).
Simple heat treatment of meat by boiling, cooking or roasting is an efficient meat preservation method for shorter periods, and can significantly reduce the microbial counts of fresh meat. Unfortunately, these products are subject to recontamination by microorganisms brought in during subsequent product handling and from the environment, but it takes some time before the spoilage flora become critical again. Although these products are not safe from the microbiological point of view, experienced manufacturers and consumers have developed methods of coping with them (Figures 6 and 7). Heat treatment is also a complementary treatment of some traditional African intermediate moisture products (Table 3).
With regard to further processing of meat, one important aspect that is widely neglected in developing countries must be stressed. Both modern and traditional meat processing methods require that raw meat of good hygienic quality is supplied to the meat processors through abattoirs. Unfortunately the abattoir sector does not keep apace with new developments in the meat processing sector. Meat processing methods is usually a private enterprise, while abattoirs are often publicly run or public facilities leased to private entrepreneurs. The recent change to market economies in many countries has only exacerbated the problem, since a great number of small hygienically unsatisfactory slaughtering facilities, mostly run by private businesses, have opened up. It has also been observed that reasonably good central abattoirs have been abandoned and cities are now being supplied by many clandestine slaughterhouses because of lower costs resulting from the absence of expensive hygienic facilities and proper meat inspection. This development is clearly detrimental to any progress in meat processing. It is often the case that meat processors cannot obtain raw meat of good hygienic quality for further processing, a fact that also has serious consequences for the quality of processed products (FAO, 1991b).
It is therefore imperative that urgent measures are taken in the abattoir sector. If the situation remains unchanged, serious constraints in supplying expanding populations with meat and meat products can be expected. FAO has provided technical advice to a number of medium-sized abattoir projects and has launched a programme on small-scale rural slaughterhouses; however, much more investment is needed to upgrade the abattoir sector in developing countries.
In 1987, FAO launched a programme for the establishment of small-scale modular slaughterhouses in rural areas in order to improve hygienic slaughtering and meat handling and to reduce meat losses. Since adequately trained staff are essential for the proper functioning of slaughterhouses, workers who are to operate the small-scale modular slaughterhouses are trained under this programme.
Another issue often neglected in developing countries is that of adequate meat inspection. The principal reason for meat inspection is to protect consumers from zoonotic diseases. It has also been introduced in order to condemn those carcass parts that are heavily contaminated or have undergone unfavourable biochemical changes and are therefore not suitable for further processing (FAO, 1994e)
FAO is very much involved in all developing regions in organizing training courses in both meat technology and inspection. Training is one of the important issues in meat technology, facilitating the introduction of proper meat processing and meat preservation methods. In Asian countries, FAO regional courses are held periodically to teach participants traditional as well as modern meat processing and preservation methods. Of utmost importance is the hands-on training provided to the participants to enable them to perform and disseminate the techniques in their own countries. Similar activities have been carried out in Latin America and more are planned for the coming years.
In Africa, where meat processing is still at a rudimentary stage, meat technology courses were held from 1985 to 1990 in an FAO training centre. FAO now endeavours to encourage the establishment of small meat processing units by private entrepreneurs. It provides the technical assistance for these projects by training potential entrepreneurs. The establishment of a prototype meat processing line in an FAO project to serve meat processing needs in Africa is currently being planned. This project will assist in the development of meat products for the African market and fulfil training and demonstration requirements.
One of the main constraints in the improvement of hygiene and the technical quality of slaughtering, meat handling and by-product utilization is the lack of adequately trained personnel at all levels. Meat training activities receive considerable attention in FAO programmes. In addition to those related to the establishment of small-scale modular slaughterhouses, regional meat training courses have been conducted in Botswana for a period of six years and courses of a shorter duration have been held in the Sudan, Thailand and Costa Rica. Similar courses are foreseen in the near future.
The few examples given above are evidence of the increasingly important role of meat processing in the meat sectors of developing countries. A recent review commissioned by FAO on agroprocessing predicts a staggering increase in the consumption of livestock products in developing countries. Experience shows that this will be associated with an increasing proportion of processed meat products in the overall meat consumption. There are two reasons for this:
· With increasing meat consumption, consumers are keen to have a greater variety of meat preparations at their disposal, a demand that can be met by offering various types of processed meat.· Greater availability of carcass meat increases the amount of "manufacturing" meat, that is, less valuable meat parts not suitable for meat dishes, but which can be fully utilized for processed products. The accessibility of sufficient raw material will stimulate meat processing, which is an optimal and very economical way of using all available carcass parts for human consumption.
In the near future, meat processing technologies and equipment will be introduced into most developing regions. In every region it can be observed that the different levels of development of individual countries are reflected in the technical standards of their meat processing capacities. In some countries, at least in their major cities, Western standards have almost been reached, with attractive processing and sales facilities for a variety of meat and meat products, all kept under refrigeration. Other countries still have less sophisticated facilities or products, but they are certain to catch up in a few years with even the most advanced countries. There is also a third category of countries that have very traditional meat marketing methods, where a longer period of structural and technical development is required.
FAO. 1985. Dried salted meats. charque and carne-de-sol. FAO Animal Production and Health Paper No. 51. Rome, FAO.
FAO. 1990. Manual of simple methods of meat preservation. FAO Animal Production and Health Paper No. 79. Rome, FAO.
FAO. 1991a. FAO consultancy report on traditional Chinese meat products.
FAO. 1991b. Guidelines for slaughtering, meat cutting and further processing. FAO Animal Production and Health Paper No. 91. Rome, FAO.
FAO. 1993. Report on FAO Seminar on Meat Drying and Other Low Cost Meat Preservation Methods in Africa, 16 to 19 March 1993, Accra, Ghana. Rome, FAO.
FAO. 1994a. FAO production yearbook. Vol. 47. Rome, FAO.
FAO. 1994b. Medium-term prospects for agricultural commodities: projections to the year 2000. FAO Economic and Social Development Paper No. 120. Rome, FAO.
FAO. 1994c. Agro-industries in FAO. Consultancy report.
FAO. 1994d. Integrated grading and solar drying of meat. Project document.
FAO. 1994e. Manual on meat inspection for developing countries. FAO Animal Production and Health Paper No. 119. Rome, FAO.
FAO. 1995. Development and promotion of value added meat products. Project document.
Karmas, E. 1976. Processed meat technology. New Jersey, USA, Noyes Data Corporation.
