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 water
Label and store the cans in a cool and dry
place.
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