Use Of High Concentration Of Sugar And Salt

Use Of High Concentration Of Sugar And Salt :

 Sugar  and  salt  aid  in  the  preservation  of products  in which it is used due to their ability to bind water and make it unavailable for microbial growth. Salt is an effective preservative because it also ionises to yield chlorine ion, which is harmful to organisms and reduces the solubility of oxygen in moisture, which are essential for the growth, and multiplication of microorganisms.

Jams, jellies and fruit juices are an important class of fruit products preserved using high concentration of sugar. Pickles are preserved using high concentration of salt.

Jam :

Jams are prepared by boiling fruit pulp with sufficient amount of sugar to a reasonably thick consistency, firm enough to hold the fruit tissue in position. In preparing jam, the fruit is crushed or finely cut and measured quantity of sugar and preservatives are added so that when cooked, the mass is fairly uniform throughout.

Jams can be prepared from all varieties of pulpy fruits such as grapes, mango, sapota, banana, guava etc.

Jelly :

Jellies are prepared by boiling fruits in water. The extract obtained is strained and measured quantity of sugar is added to it. The mixture is then boiled to a stage at which it will set to a clear gel. A perfect jelly should be transparent, well set, but not too stiff and should have the original flavour of the fruit. It should retain its shape when removed from the mould. Usually fruits such as guava, pineapple, apple, grape and a mixture of fruits rich in pectin can be used for the preparation of jellies.

Fruit Juices :

Fruit beverages are prepared from different fruits such as apple, mango, grapes, lime, pineapple, sapota and in different forms such as pure juices, crushes, squashes and cordials.

The ratio of sugar and fruit juice in the preparation of various beverages are as follows :

Crushes      -        25% fruit juice and 55% sugar.

Squashes    -        25% fruit juice and  45% sugar.

Cordial       -        Clarified juice 1 litre and 250 gm sugar.

In the preparation of fruit juices, citric acid is usually added to clarify the sugar syrup. Preservatives such as sodium benzoate are added to tomato and grape juices while potassium meta bi-sulphite (KMS) is added to all other fruit beverages.

Pickling :

The preservation of fruits and vegetables in common salt, vinegar, oil and spices is referred to as pickling. Salt binds the moisture in the food and thereby prevents the growth of microorganisms.

The layer of oil that floats on the top of pickles prevents the entry and growth of microorganisms like moulds and yeast. Spices, like turmeric, pepper, chilli powder and asafoetida retard the growth of bacteria.

Vinegar lowers the pH of the product thereby providing an unfavourable acidic environment for microbial growth. Mango, lime, ginger, garlic, tomato, chilli, mixed vegetables such as beans, carrot, cauliflower and peas are used widely in the preparation of pickles.