Food preservation: definition, principles and importance
Preservation keeps food safe and acceptable for longer. It rests on three principles: control microbes, stop self-decomposition and prevent damage by pests and physical causes.
Definition
Food preservation is the treating and handling of food so that it does not spoil, or spoils very slowly, for a long time, while keeping as much as possible of its nutritive value, colour, flavour and texture (Srilakshmi). It is more than storage: it acts on the causes of spoilage.
Principles of food preservation
| Principle | How it is done | Examples |
|---|---|---|
| 1a. Keep microbes out (asepsis) | Clean handling, natural or sealed covers | Egg shell, coconut shell, banana peel; aseptic cartons; clean milking |
| 1b. Remove microbes | Washing, trimming, filtration, centrifuging | Washing vegetables; filtering clear juices and water |
| 1c. Hinder their growth | Cold, drying, high sugar or salt, acid, low oxygen, smoke, chemicals | Refrigeration, vadam drying, jam, pickles, vacuum packs, sodium benzoate |
| 1d. Kill them | Heat, irradiation, some chemicals | Pasteurisation, canning, gamma irradiation |
| 2a. Destroy or inactivate the food's enzymes | Blanching or other heating | Blanching peas before freezing |
| 2b. Delay chemical reactions | Antioxidants, removing oxygen, cool dark storage | Antioxidant in refined oil; nitrogen-flushed chips packets |
| 3. Prevent damage by insects, animals and mechanical causes | Pest-proof packing, fumigation, pest control, careful handling | Airtight dal bins; padded crates for mangoes |
Importance of food preservation
- Increases shelf life and reduces wastage of seasonal gluts (mango, tomato).
- Makes seasonal foods available all year: mango pickle, amla murabba, dried peas.
- Adds variety to the diet: jams, squashes, papads, vadams.
- Makes transport and storage to far places easier: milk powder for hilly areas, rations for soldiers.
- Helps stabilise prices: surplus is stored instead of dumped.
- Improves safety: pasteurised milk is free of disease germs such as those of tuberculosis.
- Saves time and fuel at home: ready-to-cook mixes, frozen parathas.
- Feeds people in emergencies and supplies army and space rations.
- Creates employment: home-scale pickle, papad and squash units run by women's self-help groups.
Good preservation saves nutrients as well as food: quick blanching keeps more vitamin C than long boiling, and dried amla or drumstick-leaf powder brings vitamins into the off-season diet. Home-scale preservation also gives women's self-help groups an income.
2 marks: “Define food preservation.” Treating and handling food to prevent or slow spoilage for a long time while keeping its nutritive value, colour, flavour and texture.
5 marks: “Explain the importance of food preservation.” Shelf life, less waste, seasonal foods all year, variety, transport, price stability, safety, convenience, emergencies, employment; one example each.
10 marks: “Discuss the principles of food preservation with examples.” Three principles with sub-points (keep out, remove, hinder, kill microbes; enzymes and chemical reactions; pests and physical damage), each with an Indian example; close with the hurdle idea.
Principles = Microbes, Self-decay, Damage: keep out, remove, hinder, kill; stop enzymes and reactions; stop pests and knocks.