INTERNATIONAL REGULATIONS FOR NATURAL PRODUCTS USED AS FOOD ADDITIVES

Introduction

Foods moving in international trade are subject to a variety of constraints, including basic food quality and safety laws and regulations. These are officially applied by importing countries to protect consumers, to ensure fair food trading practices and to prevent commercial fraud.

Food control agencies of importing countries generally apply regulations which give them authority over such factors as food safety, hygiene, quality, packaging, labelling, handling and storage. In general, these regulations include precise requirements, which must be met if food products are to be admitted into the importing country. For example, regulations often indicate levels of contaminants (microbiological, agricultural and veterinary, environmental and radioactive) and levels of additives that must not be exceeded. These are often referred to as sanitary requirements. Other regulations, which are commonly referred to as quality requirements, include parameters concerning the essential composition, labelling and description of foods. Food products which do not comply with these requirements, will often result in their rejection or detention.

While the need to protect consumers from health hazards and deception is beyond question, the potential for applying national regulations in an inequitable or discriminatory manner is ever present. The application of such inequitable or discriminatory practices amounts to non-tariff technical barriers, which impede, rather than facilitate, international trade in foods.

Codex Alimentarius Commission

The importance of non-tariff technical barriers to trade in impeding international trade in foods is recognised by the major food exporting and importing nations. The Codex Alimentarius Commission, which is administered by the Joint FAO/WHO Food Standards Programme, was established in part in response to the potential for the application of such non-tariff barriers to trade. The work of the Commission has been specifically recognised under the World Trade Organisation (WTO) Agreements on Sanitary and Phytosanitary Measures and on Technical Barriers to Trade.

In undertaking its work on the establishment of maximum levels for food additives in foods, the Commission relies on the use of independent scientific advice provided by FAO and WHO through the Joint FAO/WHO Expert Committee on Food Additives (JECFA). For almost 40 years, the recommendations of JECFA have formed the essential basis for countries to judge the acceptability and safety of these compounds and have set the parameters for fruitful intergovernmental Codex discussions on additives. Similar advice has been provided on an ad hoc basis by FAO and WHO in the areas of Contaminants (including radionuclides), Food Hygiene, Nutrition, Analytical Methods, Protein Quality Evaluation and Labelling.

The use of food additives is regulated at international level by Codex standards. Only food additives, which have been evaluated by JECFA and found acceptable for use in foods, are included in the Codex General Standard and are permitted for use in foods. Food additives are only included in Codex standard when the substance does not present any risk to the health of the consumer at the levels of use proposed. Acceptable Daily Intake, or equivalent assessment, established for the additives and its probable daily intake from all sources are taken into account before the inclusion of food additives in Codex standards.

Food additives used in accordance with the Codex General standard, should be of appropriate food grade quality and should at all times conform with the applicable Specifications of Identity and Purity recommended by the Codex Alimentarius Commission or, in the absence of such specifications, with appropriate specifications developed by responsible national or international bodies.

Food additives are classified according to their functional class but can be distinguished between natural and synthetic products. The division between natural and synthetic food additives cannot be considered separated by a net mark, because many natural products are produced synthetically and many synthetic products are produced by modifying natural products or using for their production biological systems such as fermentation.

One of the main differences between natural and synthetic food additives consists in the fact that for synthetic products it is quite easy to establish Specifications of Identity and Purity while for natural products it is more elaborate to establish such specifications due to the complex nature of the products and to some differences depending on areas of production, climatic and soil conditions and sources which can influence notably the composition of the product.

Principles for the safety assessment of food additives in food

More than 500 substances have been evaluated and provided with specifications for purity and identity by JECFA. Specifications of food additives are intended to serve as a guide for manufacturers and users of the additives, as well as the basis for new or revised national legislation or regulation of member countries of FAO and WHO.

JECFA has always operated on the principle that testing requirements for all food additives should not be the same. Such factors as expected toxicity, exposure levels, natural occurrence in food, occurrence as normal body constituents, use in traditional foods, and knowledge of effects on man should be taken into account. In relation to carcinogenic hazards, the Committee has stated that "the scope of the test required should depend on a number of factors, such as the nature of the substance, the extent to which it might be present in food and the population consuming it". More generally, the Committee has requested data on, inter alia, methods of manufacture, impurities, fate in food, levels of use of food additives in food, and estimates of actual daily intake, and concluded that such information "was important and relevant both for the toxicological evaluation and for the preparation of specifications"

Naturally occurring polysaccharides

The term ‘gums’ is used to describe a group of naturally occurring polysaccharides which find widespread industrial use because of their ability either to form viscous solutions or gels or to stabilise emulsions and dispersions. A convenient means of classifying gums is according to their source and Table 1 gives details of gums commonly used.

Polysaccharide gums are poly disperse materials containing molecules with a broad range of molecular masses and usually differ to a greater or lesser extent in their carbohydrate structure or make-up depending on their source and method of extraction or manufacture. Such differences in composition commonly leads to variability in properties.

Tree Exudates

Gum exudates differ considerably chemically. Gum arabic (Acacia senegal) consists of three water-soluble fractions, namely an arabinogalactan (± 90 %) and two arabinogalactan-protein complexes which differ in their molecular size and in the proportion of the proteinaceous material associated with each. Gum tragacanth consists of a water-swellable fraction called tragacanthic acid (or bassorin) (60 - 70 %) and a water soluble fraction called tragacanthin. Gum Karaya is a heavily acetylated polysaccharide composed of chains of a -D-galacturonic acid and a -L-rhamnose. Gum ghatti has a main chain of alternating 1,4-b -D-glucopyranosyluronic acid and 1,2-a D-manno-pyranose units and contains numerous side-chains and branches consisting of L-arabinose, D-galactose and D-glucuronic acid.

Seaweed Extracts

Seaweed gums constitute the structural component of the plant and are isolated by acid or alkaline extraction followed by precipitation and drying. Agar and carrageenan are both polygalactans. Agar consists of two components, namely agarose (50 - 90 %) and agaropectin. The carrageenans are a group of linear sulphated galactans and three types are available commercially: kappa, iota and lambda.

Microbial Gums

Xanthan and gellan gums are extracellular polysaccharides obtained from the aerobic fermentation of the respective bacteria in batch culture. Xanthan gum consists of a linear 1,4-linked-b -D-glucopyranose main chain with a trisaccharide side-chain on alternate glucose residues. Gellan is a linear molecule with a tetrasaccharide repeating unit consisting of two glucopyranose residues, glucuronic acid and rhamnopyranose.

Table 1: Classification of gums

Note:   NS - ADI not specified
            NA - ADI not allocated - The year refers to the latest evaluation by JECFA
            E Emulsifier; GA Gelling Agent; GFA Gel-Forming Agent; S Stabilizer;
            TA Thickening Agent

Food uses

Whilst our modern life style has led to an increasing demand for convenience foods our growing awareness of the relationship between food and health has increased the requirement for high-fibre, low-fat food products. These factors have resulted in a considerable interest in the use of hydrocolloids, including various gums, modified starches and gelatine, in foods and this is expected to continue in the years ahead.

Gums have a major influence on the structural characteristics, texture and overall appearance of food products, even though they are usually present at concentrations of less than 1%. On food labels they are commonly referred to as ‘stabilizers", ‘thickeners’ or ‘gelling agents’, and in fact they may serve a number of functions such as enhancing viscosity, inducing gelation, emulsifying oils, stabilising foams and inhibiting ice or sugar crystallisation.

Dietary Importance

Food gums are purified soluble polysaccharide constituents of plant cells. Purified food gums are used in the food industry to stabilise emulsion and improve the texture of food. They are also used as medicines in the prevention and treatment of diabetes mellitus, obesity and hyperlipidaemia, and in the treatment of constipation.

Food gums cannot be digested in the mammalian small intestine, where they tend to form viscous solutions with dietary water and digestive secretions. Viscous solutions are antimotility agents; they impair the effects of gastrointestinal contractions in delivering food from the stomach into the small intestine, in mixing complex macronutrients with digestive secretions and in making the products of digestion available to the absorptive surface. In effect nutrients remain trapped in the gum matrix. This is thought to result in a marked reduction in the rate of absorption of rapidly absorbed substances, such as glucose and probably also in the degree of absorption of nutrients that are absorbed more slowly, such as fat and certain micronutrients.

Food gums vary in the degree to which they may be broken down by colonic bacteria. Pectin and guar are rapidly metabolised to short-chain fatty acids, yielding large amounts of gases (carbon dioxide, hydrogen and methane). Acetic acid, propionic acid and butyric acid are the major products of polysaccharide fermentation in the colon, and they each make a contribution to the energy economy.

Conclusions

All gums indicated in Table 1 have been evaluated by JECFA, which established for all products, except gum ghatti, ADI ‘not specified’.

Gum ghatti was evaluated by the Committee in 1980, 1982 and 1985. It has the typical heteroglycan structure of other gums in food additive use. Notwithstanding this, the Committee considered that data to allow evaluation for food additive use were insufficient. No toxicological monograph was prepared. The existing specifications were maintained as tentative.

ADI not specified is a term applicable to a food substance of very low toxicity which, on the basis of the available data (chemical, biochemical, toxicological, and other), the total dietary intake of the substance arising from its use at the levels necessary to achieve the desired effect and from its acceptable background in food does not, in the opinion of JECFA, represent a hazard to health. For that reason, and for reasons stated in individual JECFA evaluations, establishment of an acceptable daily intake expressed in numerical form is not deemed necessary by JECFA. An additive meeting this criterion must be used within the bounds of Good Manufacturing Practice (GMP). According Codex definition, GMP include

1. The quantity of the additive added to food shall be limited to the lowest possible level necessary to accomplish its desired effect
2. The quantity of the additive that becomes a component of food as a result of its use in the manufacturing, processing or packaging of a food and which is not intended to accomplish any physical, or other technical effect in the food itself, is reduced to the extent reasonably possible; and,
3. The additive is prepared and handled in the same way as a food ingredient

At its 22nd Session, the Codex Committee on Food Additives and Contaminants agreed to endorse the use of food additives with non-numerical ADIs for use in foods in general according to GMP and without specific reference to their technological function. It also agreed to Annex a list of food categories or individual foods where the use of these additives was not allowed or was restricted, based on a similar list currently in effect in the European Community. The list of food additives with non-numerical ADIs and the Annex including food categories is attached as Appendix I to this paper.

In view of the fact that at present risk analysis was considered to be an integral part of the decision-making process of Codex, the Committee on Food Additives and Contaminants is working on the elaboration of procedures for risk assessment and management and is considering that a screening method should be used to evaluate additives which require further assessment of their exposure, and that an appropriate number of these additives be referred to JECFA for the evaluation of data on probable human exposure.

References

Codex Alimentarius Commission, ALINORM 97/12A, Report of the Twenty-Ninth Session of the Codex Committee on Food Additives and Contaminants, 1997

Codex Alimentarius Commission, ALINORM 97/37, Report of the Twenty-Second Session , 1997

Evaluation of certain food additives and contaminants (Twenty-ninth report of the Joint FAO/WHO Expert Committee on Food Additives), WHO Technical Report Series, No 733, 1986

FAO, Summary of Evaluations Performed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), ILSI Press, 1996

Gums pp 2267 - 2288. In: Encyclopaedia of Food Science, Food Technology and Nutrition, London (UK). Academic Press. 1993

JECFA, Compendium of Food Additive Specifications, FAO Food and Nutrition Paper 52/1, 1993

It should be noted that Codex has established additional provisions on the use of food additives in certain Codex Commodity Standards and may establish provisions to Schedules 1 and 2 to this Standard in the future.

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