Food is vital for humans. Cereals, grains, vegetables & fruits all in the food pyramid is easily available for consumption. Preparing a few dishes everyday can be substituted with the products prepared with an aim to last for longer days or months.“ Make hay while sunshine” the same applies here too. For the sake of the winter season, when there is heavy snowfall or other seasonal difficulties, or to carry food for long distance travel, to store food for further use started. But food is subject to spoilage on storage
On the basis of ease of spoilage, foods can be placed in three groups.
1. Stable or non-perishable foods: These foods, which do not spoil unless handled carelessly, include such products as sugar, flour, and dry beans.
2. Semi- perishable foods: If these foods are properly handled and stored, they will remain unspoiled for a fairly long period. Eg. Potatoes, some varieties of apples, waxed rutabagas, and nutmeats.
3. Perishable foods: This group includes most important daily foods that spoil readily unless special preservative methods are used. Meats, fish, poultry most fruits and vegetables, eggs and milk belong in this classification.
Most foods fall into one of these three groups; but some are near enough to the borderline to be difficult to place.
To make the food last longer & avoid spoilage, a few ingredients are added, they are termed as preservatives. A substance when added to food, is capable of inhibiting, retarding or arresting the process of fermentation, acidification or other decomposition of food.
Class I preservatives are common salt, sugar, dextrose, glucose, wood smoke, spices, vinegar or acetic acid, honey.
Class II preservatives are Benzoic acid, sulphurous acid, nitrates of sodium or potassium in respect of jams, lactic acid, calcium phosphate, & niacin.
Vegetables/ fruits are preserved in the form of canning. Canning is a process where the vegetable or fruit is made into slices and kept in a can with sugar syrup & salt water.
This practice is followed world- wide since time immemorial The technological progress in food preservation gained momentum mainly after the outbreak of the first world- war when supply of large quantities of vegetables, fruits, E t c had to be arranged for the armed forces. World war II also provided another strong impetus to the growth of the industry. So, the food preservation industry developed towards the close of 18 th century. The French Government announced a price of 12,000 francs for the discovery of a satisfactory method of preservation during the Napoleonic wars. In 1810 Nicholas Apperd, a Paris confectioner and distiller, invented a process for preserving foods in glass containers and won the prize. He also published a book entitled “The Art of preserving animal and vegetable substances for many years.” This is the first book published on modern canning. In honour of its discoverer, canning is still known as “Appertizing”
Apperd packed his food in glass containers, added sufficient water to cover the food, placed the corks loosely on top and heated the containers in a water bath to obtain the temperature of 192- 212 degree Fahrenheit at the centre of the containers. By this method, he succeeded in preserving several kinds of food. This preserving action is due to exclusion of outside air.
Gay-Lussac, who studied apped’s process at the intense of the French Government, concluded that spoilage in foods was essentially a process of oxidation which could be prevented by exclusion of air from the container. This hypothesis was universally accepted till the time of Louis Pasteur. He provided correct explanation of the change through his discovery of microbes down about 1860. He provided that the microorganisms are the real cause of spoilage and they can be destroyed by giving heat treatment. He also found out that foods can be stored in suitable containers. He introduced the term “Pasteurization” which means heat treatment of a food at sufficiently high temperature to kill the majority, though not all, of the microorganism, there by prolonging the normal keeping quality of that food.
In England Thomas saddington, who had picked up the general principles of the method of apperd while travelling in France, was the first to describe the method of canning of food in 1807. According to Bitting peter Durand”, another English man obtained in 1810, the British patent on canning of foods in tin containers. Canning of fruits on a commercial scale was introduced in U.S.A. in 1817 by William underwood.
From then onwards canning of fruits & vegetables commenced which accessed the consumption of all vegetables & fruits in all seasons.
CANNING OF FRESH PEAS
Canning of fresh peas as per F.P.O. specifications
Things needed: peas. Sugar, salt, green colour and water
1. Select fully grown fresh peas
2. Weigh & wash in cold running water, de=shell peas.
3. Grade the peas by using sieves with different mesh sizes, or by floating them in brine solution.
4. The peas are blanched in boiling water for 2-5 minutes and rinse in cold water.
5. The prepared peas are filled in cans
6. Prepare 2 % salt solution and 2.5% sugar solution by adding green colour.
7. Drain and pour into can, leaving a head space of half an inch.
8. Exhaust the cans for 7-10 minutes at 192 degree Fahrenheit
9. Code and seal the cans
10. Process the cans for 45 minutes under pressure
11. Cool cans in cold running waterLabel and store the cans in a cool and dry place.