During processing of food, several chemicals are added to it to augment its shelf life and to make it more attractive as well. Main types of food additives are listed below:
(i) Food colours
(ii) Flavours and sweeteners
(iii) Antioxidants
(iv) Fat emulsifiers and stabilizing agents
(v) Flour improvers
(vi) Preservatives
(vii) Nutritional supplements such as vitamins, minerals, etc.
Except for nutritional supplements none of the above food additives has any nutritive value.
In this section we will learn about preservations and sweeteners.
1. Food preservatives
Food items containing moisture get spoiled due to growth of micro-organisms. Growth of micro-organisms in a food material can be inhibited by adding food preservatives. Food preservatives are classified into two groups - Class I and Class II. Class I preservatives comprise sugar, table salt and vegetable oils. The Class II preservatives are chemical preservatives. The chemical substance which is used as food preservative should not be harmful to the human beings. These chemical substances which are supplemented to food materials to avoid their spoilage are called as chemical preservatives.
Benzoic acid or its sodium salt, sodium benzoate is usually utilized for the protection of food materials. For the preservation of fruits, fruit juices, squashes and jams sodium benzoate is used as preservative because it is soluble in water and hence easily mixes with the food product. 0.06% to 0.1% concentration of sodium benzoate is sufficient for the preservation of fruit juices and squashes. Sodium benzoate is metabolized by conversion to hippuric acid, C6H5CONHCH2COOH which is finally excreted in the urine.
Potassium metabisulphite or sodium metasulphite is used for the preservation of colourless food materials such as fruit juices, squashes, apples, lichies and raw mango chutney. These are not used for preserving coloured food materials because sulphur oxide produced from these chemicals is a bleaching agent. These preservatives on reaction with acid of the juice liberate sulphur dioxide which is very effective in killing the harmful micro-organisms present in the food and thus prevents it from getting spoiled.
2. Artificial sweetening agents
Sugar or sucrose is the natural sweetening agent. However, excess consumption of sugar leads to many diseases such as obesity, diabetes, coronary heart disease. Many artificial sweetening agents have been isolated which are much sweeter than sugar. These artificial sweetening agents are non-nutritive in nature and are used as substitutes for sugar in foods and beverages especially soft drinks. Some examples of artificial sweetening agents are saccharin, cyclamates. Saccharin (Ortho-sulphobenzimide) is about 550 times sweeter than cane sugar or sucrose.
The use of cyclamates as sweetening agent has been banned in many countries in view of suspected carcinogenic effects.
Aspartame is one more artificial sweetener. It is methyl ester of the dipeptide aspartyl phenylalanine. It is approximately 100 times sweeter than sucrose.
Aspartame is unstable to heat and therefore, it can be used as a sugar substitute in cold drinks and cold foods only.
Alitame is another artificial sweetening agent. It is approximately 2000 times sweeter than sucrose. It is more stable to heat than aspartame. Since Alitame is a high potency sweetener, it is difficult to control sweetness of food while using this sweetener.
Sucralose is a trichloroderivative of sucrose. It is approximately 600 times sweeter than sucrose. It is steady at cooking temperature.