Processing of Horticultural Crops (1+2)

Introduction

Introduction
Many chemical substances are added to the food for functional purposes and in many cases these are found to occur naturally in some foods. An additive is defined as a substance or mixture of substances other than basic food ingredient present in a food as a result of any aspect of production, processing or packaging. Additives may be intentional as well as unintentional. Intentional additives are the substances deliberately added with the objective to perform a specific function and to increase the preservation life of products while, unintentional additives have no intended function in the finished product but become part of that particular product. They include preservative, antioxidants, stabilizers, thickening agents, firming agents, sequestrants, clarifying agents etc. The role of different chemicals added to the food is discussed as under:-

Objectives of adding an additive

1. To reduce wastage and improve keeping quality e.g., addition of potassium meta-bi-sulphite in squashes, benzoate in sauces, sodium propionate in bread and sorbic acids in cheese, etc
2. To improve and maintain nutritive elements e.g. addition of vitamins for enrichment, addition of vitamin D to milk, addition of iodine to salt, etc.
3. To enhance quality and consumers acceptability of the product e.g., addition of colouring agents, emulsifier, thickeners etc.
4. To facilitate the preparation of foods e.g., addition of acid to beverage, sugar in jams, jellies, etc.

Classification of food additives: Food additives are broadly classified into following categories:

1. Preservatives	5. Colouring and bleaching agents	9. Flavouring agents
2. Antioxidants	6. Stabilizers & thickeners	10. Anti-caking agents and   humectants
3. Sequestrants	7. Buffers & acids	11. Non-nutritive and special dietary    sweeteners
4.Surface-active agents	8. Nutrient supplements

Preservative: Preservative is defined as a substance which when added to food is capable of inhibiting, retarding or arresting the process of fermentation, acidification or other decomposition of food. According to Indian Food Laws, the preservatives are classified into following two classes as Class I and Class II preservatives.

i) Class I preservatives: Class1 preservative broadly include naturally occuring substances and there is no maximum limit specified under law for their use. The common examples of class I preservative are common salt, sugar, dextrose, glucose syrup, spices, vinegar or acetic acid, honey and edible vegetable oils.

ii) Class II preservatives: Class II preservatives are chemical substances added to the food. They include sulphurous acid and salts thereof, benzoic acid and salts thereof, sorbic acid including its Na, K and Ca salts, nitrates or nitrites of Na or K, niacin, sodium and calcium propionates, methyl or propyl parahydroxy-benzoate (parabens), propionic acids including esters or salts and Na, K and Ca salts of lactic acid etc. In fruit and vegetable products generally sulphuric acid and its salts, benzoic acid and its salt and sorbic acid and its salt are used. Class II preservatives being chemical substances have maximum limit beyond which they should not be present in different products. Maximum limit for these substances under FPO (Fruit Products order) in different fruit and vegetable products vary between 40 to 2000 ppm (SO2), 120 to 750 ppm (benzoic acid) and 50 to 500 ppm (sorbic acid) depending upon the type and category of foods. When two or more preservatives are added to the food, their ratio shall be calculated proportionally to their maximum limit.