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Introduction
Food preservation can be defined as the science which deals with the process of prevention of decay or spoilage of food thus allowing it to be stored in a safe condition for future use. All foods gradually undergo deterioration or spoilage from the time they are harvested or manufactured. Some commodities spoil rapidly, while others can keep for longer but limited periods. The basic purposes of food preservation are: 1. Extension of shelf-life of foods thus increasing the supply. 2. Ensuring the availability of seasonal foods throughout the year. 3. Adding variety to the diet. 4. Saving time by reducing preparation time and energy. 5. Stabilizing firm prices and prices of food. 6. Improving the nutritional qualities. The food spoilage might be due to growth and activity of micro-organisms, insects or rodents, action of enzymes. Chemical reactions and physical changes take place during processing by burning, drying, freezing etc. Depending upon the easiness of spoilage and the level of perishability the foods have been classified into three categories:
1. Non-perishable or relatively stable: The foods that do not spoil easily and can stored for several months unless handled carelessly. They have low moisture content and are not easily susceptible to spoilage by micro-organisms. They include mature food grain, cereals, pulses, nuts, sugar, dry beans etc. 2. Semi-perishable or protectable: These foods can be kept for about a week to a month’s time and remain unspoiled for fairly long period with proper care. They contain comparatively much less level of moisture content and also contain certain natural inhibitors to spoilage such as roots, vegetables and eggs. These include potatoes, flours, roasted oil seeds, biscuits, onions, dried fruits and other dehydrated foods. Some other examples of prepared foods are pasteurized milk, smoked fish and pickled vegetables. 3. Perishable foods: the perishable foods are those which deteriorate/spoil quickly after harvesting and cannot be kept for more than a day or two without affecting their quality. These food stuffs have a higher degree of moisture content and are highly susceptible to spoilage. The typical examples of such foods include most fruit and vegetables, milk, meat, fish and poultry. |
Last modified: Saturday, 3 March 2012, 10:44 AM