A number of fruits and vegetables are grown in our country and their production is often so high that every year we have substantial seasonal surplus, since these are highly perishable commodities and cannot be stored for long in the fresh condition, they are available at very low price during the season. So if these seasonal fruits and vegetables are preserved, they can be used in all seasons to enrich the diet of the people. Certain techniques of preservation are simple and can be adopted at the domestic level. Preservation of fruits and vegetables has been a part of the Indian culture since long, as pickles and chutneys are very popular items in diet.
Let us discuss about the methods used in food preservation.
1.Heat Processing Method-
To sterilize the contents of food before they are packed air tight, these foods are heated on a particular temperature this method is referred as heat processing. The examples of this method of food preservation are canning of fruits and vegetables which needs more attention since any lack found in the container makes the product unfit for the consumption.
2.Preservation using Salt-
For making pickles this method is more commonly used, when the salt usage in food occurs more than 15% then they are suitable for effective preservation method, here salt acts as an preservative.
3.Preservation using Sugar-
In this method sugar absorbs the water content of the fruits thereby preventing the growth of microorganisms, thus acts as a good preservative. Sugar usage in food when becomes more than 68% then the sugar in it act as a preservative. Examples of this method are jam, jellies preparation method.
The mechanism behind this process is so simple, generally microorganism needs the moisture for growth, when the moisture level is reduced then the microbial activity is decreased and the shelf life of the product is increased. The methods used are sun drying, air drying and freeze drying.
5.Preservation Using Vinegar-
Pickles and sauces were preserved by this method, to ensure the good results the vinegar level should not be less than 2 %.
As the word itself describes preservation done by using chemicals; the chemicals used are benzoic acid (benzoates), sulphurdioxides (sulphites). The juices and squashes are prepared by this method. According to the Indian Fruits Product Order the maximum amount of sulphur dioxide in crushes and cordials are 350 ppm.
In this deep freezing method the food is exposed at the temperature below the freezing point, at this level the microbial activity on food is less and the enzyme reactions on food were controlled in action. When the temperature level goes higher than 15 degree Fahrenheit then again microbial activity on food starts and food spoilage occurs, this is just a temporary method so foods when has to increase in shelf life are not recommended this mode of usage.
While choosing foods for preservation select fresh foods without damage and blemish, thereby to get good and better quality products. While doing jam preparation select ripe fruits to get higher quality of pectin. Avoid metal containers for storage of food, only clean, sterilized and dry bottles or jars should be used for food preservation. Food preservation is a technology and a scientific approach to increase the shelf life of food product, don’t waste food and preserve for long term usage and get benefited out of it when it is unavailable at that time.
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