FOOD ADITIVES

Food additives are intentionally added substances to food. These are normally added in small quantities and are not consumed as foods by themselves. These serve as aids in the preparation and processing of food, to improve quality, appearance, taste, odour, texture, consistency, acidity or alkalinity etc.

Food additives aid the manufacturers but the benefits to the consumer are often debated.

Food additives may be classified as follows:-

1. Preservatives

2. Anti-oxidents

3. Permitted colours

4. Sweetening agents

5. Emulsifiers and Stabilizers

6. Anti-caking agents

7. Firming agents – humectants

8. Acids, Buffers and Bases

These do not include vitamins, herbs and spices and contaminants arising from agricultural practice etc.

Food laws stipulate that labels must list all ingredients in descending order of proportion by weight. Thus food additives appear almost at the end of the list as a code number. These numbers are based on an internationally accepted system replacing long chemical names. The prefix letter E appearing before the number indicate that it has been approved by the European Community e.g. E220 refers to Sulphur dioxide.

Adverse reactions to food additives occur only in a small proportion of the population. Such people could avoid these on recognising the presence of the particular additive from the label.

Preservatives

Preservatives means a substance which when added to food is capable of inhibiting, retarding or arresting the process of fermentation, acidification or other decomposition of food. These acts as antimicrobial agents and inactivate or inhibit the growth of moulds and bacteria in foods.

The preservative regulations permit the presence of only specified preservative within prescribed limits in some foods.

Sulphur dioxide in the form of gas, in solution as sulphurous acid or as sodium, potassium and calcium sulphite is commonly used as a preservative in fruit juices, jams, cider, bear etc. while benzoic acid derivatives are also used in fruit juices, diabetic jams, bear etc. weight by weight benzoic acid is only half as effective as sulphur dioxide.

Sodium nitrate and sodium nitrite are permitted within maximum limits in cured meat, salami, bacon and ham and some cheese. Added nitrates and nitrites are prohibited in all infant foods. These have the potentiality of forming the carcinogenic nitrosoamines, which are harmful to all including infants.

Propionic acid is a permitted preservative in flour confectionary Christmas pudding and in bread within maximum limits. However, it is banned in Germany. Sorbic acid is also permitted in flour confectionary, cheese, cider, yoghurt, curd and some ready to drink beverages.

Biphenyls, 2-hydroxy biphenyls and 2-thiaxol-4-benzimidazole are permitted in citrus fruits.

The abusive and unlawful use of formalin as a preservative in fish and malathion in cereals and pulses have occurred in some developing countries. Malathion is freely available in tropical countries as it is now widely used for spraying against malarial vectors.

Table 1 presents a summary of the permitted preservatives in specified foods and maximum allowed levels in mg/kg.

Specified food	Permitted Preservative	Maximum allowed level mg/kg
1. Beer	SO2, Benzoic acid or other derivatives of Benzoic acid	70
2. Bread	Propionic acid	3000
3. Cheese	Sorbic acid	1000
4. Cider Wines	SO2 or Sorbic acid "	200 350
5. Desiccated Coconut	SO2	50
6. Flour Confectionery	Propionic or Sorbic acid	1000
7. fresh fruits a) Citrus b) Grapes	Biphenyl 2-Hydroxy Biphenyl 2-Thiaxol-4-yl benzimidazole SO2	70 12 20 15
8. Fruit Juices	SO2 Benzoic acid or derivatives	350 800
9. Jams	Residual SO2	100
10. Diabetic Jams	SO2	100
11. Sausages	SO2	450
12. Meat cured	NaNO3 NaNO2	500 200
13. Ready to drink beverages	SO2 Benzoic acid or derivatives Sorbic acid	70 160 200
14. Yoghurt	Sorbic acid SO2 Benzoic acid or derivatives	300 60 120
15. Curd	Sorbic acid	300

Antioxidants

Antioxidants are substances capable of delaying, retarding or preventing the development in food of rancidity or other flavour deteriorations and spoilage due to oxidation and prolonging shelf-life.

Ethyl, propyl, octyl and dodecyl gallates are commonly used antioxidants with a maximum permitted level of 100 mg/kg in edible oils and fats, ghee and margarine while the amount for butter fat used for manufacturing purposes is reduced to 80 mg/kg.

Butylated hydroxy anisole (BHA) or butylated hydroxy toluene (BHT) or a mixture of both are allowed in edible oils, fats, margarine and ghee to a limit of 200 mg/kg while the limit for butterfat used for manufacturing purposes is 160 mg/kg. Gallates, BHA and BHT are prohibited in baby foods. These included 1-ascorbic acid and tocopherols which also serve as antioxidants.

Colouring matters

Colours are as turmeric and saffron have been used in food from ancient times to please consumers. However, regulations had to be brought in to prevent the diaguise of inferior products, the use of metallic coloured salts and non-permitted coal-tar dyes in foods. Poisonous copper sulphate had been used to colour pickles, alum to whiten bread, plant extracts to colour beer and molasses, dyes to spent tea leaves, yellow colour to mask adulterated milk etc.

Only permitted colours which satisfy purity criteria are now allowed in specified foods. Regulations exist for these purposes. Also when colour is added to any food the label must state “Artificially Coloured”.

Among the red permitted colours are carmoisine, fast red E, ponceau 4R, and erythrosine BS. The blue colours are indigo-carmine, brilliant blue FCF while the green colours are S and green FCF. The yellow colours are tartrazine, amaranth and sunset yellow. Amaranth has been banned in the USA.

Raw or unprocessed meat, poultry, fish, fruits and vegetables, tea, coffee beans, ground coffee, coffee extract, bread, cream, condensed milk, dried milk, cheese and butter are not permitted to have added colours. Butter may however contain annatto and carotene. Colours are also prohibited in baby foods.

Sweetening agents

Sugars are high energy foods and these have been replaced by very low energy and non nutritional artificial sweeteners such as saccharine, cyclamates and aspartame. Saccharine and cyclamates have been accepted for carbonated drinks, gelatine deserts, pudding mixtures, jams, jellies, diet jams, cordials, custard and soft drinks. These artificial sweeteners are not permitted in baby foods.

Cyclamates still remain banned in the USA although some attempts have been made to remove this band.

Acesulfame – K is an approved sweetener in more than 20 countries

Genetic engineering has yielded some promising peptide sweeteners.

Other less sweetening agents that yield bulk in sugar free products used for special diets and by diabetics are sorbitol, mannitol and polyhydric alcohols. Thaumatin, which is 3000 times sweeter than sucrose is also a permitted sweetener in some countries. It is found in the fruit of a West African plant called Katemfe.

Non- nutritive sweeteners in food regulations limit the amount allowed in foods.

Analytical methods which include TLC, spectrophotometry and HPLC are available for the detection and estimation of artificial sweeteners.

Emulsifiers and Stabilizers

Any substance which is capable of aiding the formation of a stable mixture of two otherwise immiscible substances such as oils, fats and water is called and emulsifier and any substance that helps to maintain an emulsion which has been formed is called a stabilizer.

Edible gums and agar were used in the early days but they have been replaced now by lecithin, polyphosphates, cellulose esters, poly and partial glycerol esters, propylene glycol esters, carboxy methyl cellulose, stearyl tartrate and monostearin sodium sulphoacetate etc. These are used in bread, flour confectionery, ice-cream, margarine, chocolate, sugar confectionary, processed meats, sauces, dessert mixtures.

Wood resin or ester gum used in beverages and chewing gum and derived from the stumps of longleaf pine are a complex mixture of tri and diglycerol esters of resin acids.

Food regulations specify permitted emulsifiers and stabilizers with limits in foods and also prescribe purity criteria fro emulsifiers and stabilizers.

TLC, HPLC and GLC methods including colorimetric methods are available for the detection and estimation of emulsifiers and stabilizers.

Anti-caking agents: these are substances that ensure a free flow when poured from containers e.g. salt. Magnesium carbonate amounting to 0.3-1% is added to salt to health the free running properties. Phosphates, silicates and fatty acid salts are also used in other foods but the maximum total amount allowed is 20g/kg.

Firming agents and humectants: these enhance the texture and uniform consistency of the food. Humectants prevent foods from drying out. Glycerine, lacitol, mannitol and propylene glycol are common humectants.

Thickeners used in present day foods are modified starches, carrageenan etc. carrageenan is a plant gum derived from a variety of sea weed. It was also called Irish moss and named after a town carragheen in Ireland.

Acids, buffers and bases: these are added to maintain a constant pH level in foods.

Flavour enhancers and flavourings are used for improving the existing flavour or aroma of the food and to retain losses during processing and to make the food more palatable.

Glutamates, ribonucleotides and protein hydrolysates are used as flavour enhancers in soup mixes, sauces and meat products. Ribonucleotides include disodium inosinate and disodium guanylate.

Monosodium glutamate (MSG) is a common flavour enhancer used in Chinese restaurants. MSG is the sodium salt of glutamic acid, one of the most common amino acid found in foods. One fifth of the body’s protein is a glutamate. MSG, besides being a flavour enhancer has also a basic taste named “umane”. Excessive amounts of MSG cause the Chinese restaurant syndrome or Kwok’s Quease which includes headaches, dizziness, muscle tightening, nausea, weakness of upper arm, pains in the neck etc. MSG is prohibited in baby foods. Allergies to MSG exists, as in many other foods.

Apart from food additives already included above, there are others such as enzymes which act as catalysts. These may also act as tenderizers, flavour enhancers, stabilizers, antioxidants and preservatives.

Foods with added flavours, natural of synthetic should be labelled accordingly.

The list of food additives are increasing every year and adequate safeguards are needed. There is a joint FAO/WHO expert committee on Food additives to monitor new additives and to recommend or not their use including establishments of safety limits. The safety limits are included in the food standards established by Codex Alimentarius Commission of the FAO.

Consumers demand more additive free foods, but the food industry rely heavily on additives. Food additives, while serving the purpose for which they are added, should be safe and beneficial to the consumer.