Food preservation can be defined as the science which deals with the process of preservation of decay or spoilage of food, thus allowing it to be stored in a fit condition for future use. The process used varies with the length of storage intended. It may be as simple as boiling milk so that it may keep for 24 hours or pickling of mango or lemon where the intended period of storage may be as long as a year.
IMPORTANCE OF FOOD PRESERVATION
Food supply has to keep pace with the needs of the population. There is always a shortage of food in developing countries like India because of the demands of the increasing population. Interesting food production to meet this shortage results in wastage due to inadequate facilities available for shortage and preservation. It is therefore, important to improve and expand facilities for the shortage and preservation of food. Preservation of food helps in:
- Increasing the shelf-life of foods thus increasing the supply.
- Making the seasonal food available throughout the year.
- Adding variety to the diet.
- Saving time by teaching preparation time and energy.
- Stabilizing prices of foods.
- Improving the nutrition of the population.
Preservation increases availability of foods, thus improving the nutrition of the people. Availability of seasonal foods throughout the year also helps in stabilizing prices of such foods.
CAUSES OF FOOD SPOILAGE
Food spoilage usually refers to undesirable changes occurring in food due to the action of microorganisms, insects and enzymes. Foods vary greatly in the length of time for which they can be held in their natural form without spoilage. For purposes of food preservation, foods are classified as perishable, semi-perishable and non-perishable. Perishable foods such as milk, meat, sea foods and many fruits and vegetables begin to deteriorate almost immediately after harvest if not preserved. These foods have a high moisture content and are highly susceptible to spoilage. Foods are spoiled by the action of:
(i) Microorganisms, (ii) enzymes, and (iii) insects.
Spoilage by Microorganisms
The microorganisms that cause food spoilage are moulds, yeasts and bacteria. Some of these organisms can be used to produce desirable changes in food under controlled conditions such as the formation of curd (dahi) from milk. However, they are more often agents of spoilage. Some microorganisms can exist both in vegetative and spore form. Spores are more resistant to destruction by heat or other agents than the vegetative form.
Moulds: Mould growth on foods with its fuzzy or cottony appearance is familiar to everyone and foods with such growth on them are generally unfit to.
Spoilage by Insects: Worms, bugs, weevils, fruit flies, a moths may damage food and reduce its nutrients content and render it unfit for human consumption.
Means of preservation: Preservation of food can be achieved by chemical, biological, or physical means.
- CHEMICAL PESERVATION: It involves the addition of substances such as sugar, salt and acid, or exposure of food to chemicals such as smoke or fumigants.
- BIOLOGICAL PRESERVATION: it involves alcoholic or acidic fermentation.
- PHYSICAL PRESERVATION: it involves using methods which include temporary increases in the product’s energy level (heating and irradiation) , controlled reduction in the product’s water content ( concentration, air-drying, freeze-drying) and use of 0f protective packages.