What is Soil pH and Why is it important in farming? - Chemosmart

           Principle of Preservation

      

               Preservation of the variety of food material is done by various methods. It depends on for how much period the food material should preserve and type of food material. The different methods of preservation are as follows:

1) Preservation by addition of heat processing in various ways is perhaps the earliest and most common method of preservation. 

2) Drying or dehydration method is another method in which water part removed either by sun-drying or by mechanical method. For example storage of fish, meat, some fruits and vegetables. 

3) Freeze preservation method is used to increase the storage life of fresh fruits and vegetables, and similar other fresh food-stuffs. 

4) Preservation by addition of sugar and application of heat is a highly important method in the case of fruits which are utilized in a very large quantity to make jams, jellies, marmalades and preserves. This method is simple, cheap and easy to adopt. 

5) The use of chemical additives, which are permitted as harmless, within limits is fairy widespread in the case of a variety of squashes, cordials and other beverages. At present, only sulphur dioxide and its salts and benzoic acid and some of its ester derivatives are permitted in food. 

6) Preservation by fermentation is a very ancient and well-known method. Yeast-fermented fruit wines, which contain ethyl alcohol as natural preservative, have been prepared and used for hundreds of years. Such alcoholic liquids undergo further acetic acid fermentation into vinegar, which is an acidulant and is widely employed in pickling. 

7) Preservation by salting or bringing of vegetables and unripe fruits for e.g. Mango, Lime, Lemon etc., is very common in many parts of the world where Indian pickles are well known. 

8) Preservation of friuts and vegetables by application of U.V and ionizing radiation is of recent origin. 

Preparation of Jams:

             Jam is prepared by boiling the fruit pulp with a sufficient quantity of sugar to a reasonably thick consistency, firm enough to hold fruit tissues in position. In its preparation, about 20.4 kg of friuts should be used for every 24.9kg of sugar. It should contain not less than 68.5% soluble solids as determined by refractometer, when cold, and uncorrected for insoluble solids. Jams may be made from a single fruit, or from a combination of two or more fruits. 

Procedure (For Mango fruit) :

1) Take any fruit (Mango), weigh accurately and wash thoroughly to remove any adhering dust and dirt. Remove all unwanted parts. 

2) Peeled the friut, removed stones and then crush or sliced the fruit. 

3) Boil the fruit, if necessary, a small quantity of water is added to facilitate pulping. It is then cooked sufficiently to liberate the pectin. 

4) The pH of the fruit juice and pectin mixture should be 3.0 before sugar added. pH can be adjust by adding salts of citric or tartaric acids, or alkalies like sodium bicarbonate or calcium carbonate. 

5) Add the sugar in it. Minimum sugar should be 68.5% of the weight of the friut taken. 

6) The fruit -sugar is then boiled rapidly to concentrate the soluble solids to about 68.5 percent and also to effect the necessary degree of inversion of sugar. 

7) To avoid excessive frothing during boiling, a small quantity of butter or some other Brand of edible oil may be added to the boiling mixture. 

8) The finished jam should contain 30% to 50% invert sugar, or of glucose, to avoid crystallization of cane sugar in the jam during storage. 

9) Generally citric, tartaric or malic acid, which are natural fruit are used to supplement the acidity to the fruit for jam-making. Only permitted edible food colours should be used, if necessary, and these should be added towards the end of the boiling process. 

10) Generally, in the case of fruits rich in pectin, the weight of the finished jam is one and half times the weight of sugar taken. 

11) When jam is to be packed in cans, it should be filled hot, and the cans closed and pasteurized for about 30 minutes at 82°C to 85°C.

Flow chart for Jam preparation: