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India, one of the largest food producer countries (I in milk production, II in fruit and vegetable production and III in food grain production at world level), possesses the potential of being the biggest with the food and agricultural sector contributing around 26 percent of the Gross Domestic Product (GDP). It is a paradox that people of the country producing such huge quantities of food including fruits, vegetables, milk, cereals grains etc. are still suffering from many nutritional deficiencies in their diet, and even in some places, the stomachs of people remain unfilled for the want of food. The credit of this would predominantly go to the poor postharvest infrastructure as well as knowhow and accessibility to the facilities. All this makes us one among those countries having largest postharvest losses. The reduction of losses occuring during food handling, processing, storage, distribution and use would be an indirect way of increasing the food production and making the country self-sufficient in nutritional requirements.

Physiological Development

Fruits and vegetables can be divided into 3 stages based n their physiological development i.e. growth, maturation and senescence.

Growth: This generally refers to cell division, enlargement and differentiation ultimately giving a particular size, weight and volume to the commodity.

Maturation: It is initiated before the ceasation of growth and lasts till the onset of senescence.

Senescence: The stage when anabolic (synthetic) processes almost terminate and catabolic (degradative) processes are initiated and speeded up causing ageing and finally death of tissues.

Ripening: Stage that begins with the last stages of maturation and lasts till the beginning (first stage) of senescence. Ripening is a very important event in the life of a plant as it transforms a physiologically mature but inedible (or not preferred to be eaten) plant part into an edible, visually and olfactorily attractive and tasty commodity. Ripening marks the completion of developmental phase and is an irrevessible event.

Maturity Standards and Harvesting Indices

Harvesting : Harvesting is detaching a commodity from the point of its origin. This point of origin may be an above ground plant part i.e. shoot eg. apple, tomato etc. or an underground plant part eg potato, carrot, etc. or in water i.e. harvesting of fish from a pond (not to be covered in this book).

Storage : It can be defined as keeping the commodity fresh or processed in safe condition with minimum of deteriorative changes for later use.

Reasons of Deterioration During Storage

Packaging : Packaging of fruits, vegetables, flowers or any other commodity is chiefly done to assemble the produce in convenient units of different sizes, shapes & types for storage, transportation, marketing and distribution. The size of units may vary depending on the requirement e.g for retail marketing smaller units are preferred and for bulk transportation and storage, large units would be more convenient.

Why do we Require Packaging?

Imagine there is no packaging material and technology available. How we are going to transport apple, mango etc. to distant markets? Definitely as loose. Then how can we weigh or count the fruits being transported or marketed? This would be very difficult. Had there been no packaging the commodity would have suffered great physical, chemical and microbiological losses. It would have been very difficult to handle, manage, transport and market the produce as loose and unpacked. Therefore, the packaging of fresh as well as processed commodities was needed to contain, unitize and protect the produce.

Nature has made such a beautiful system that a fruit does not spoil unless its outer covering is removed and till it is there on the plant. For example banana will not spoil for long time if we do not remove its peel. Similar is the case with apple, guava, mango and many other fruits and vegetables. But as soon as the outer covering is removed the damage begins and the commodity is spoilt very soon.

Preservation is extending shelf life of fresh or processed food by using various methods and prevention or reduction of spoilage. Better the preservation, lesser the spoilage, more the spoilage poorer and inefficient is the preservation.

Therefore, in order to prevent or reduce the spoilage, we have to first identify and understand the causes of spoilage. There are chiefly 3 agencies that cause spoilage in fruits and vegetables i.e. (i) microorganisms, (ii) enzymes & chemical changes and (iii) man, animals, rodents, insects, etc. For effective preservation we have to check the growth and activity of these spoilage causing agencies. So, in order to prevent spoilage and preserve a perishable commodity for long time the following principles and methods are to be followed.

Essentials for Quality Product Preparation

Plant ripened red tomatoes should be selected. Yellow and green fruits on processing yield dull colour and turn brown due to oxidation.

Never use iron equipment for processing. Lycopene oxidizes and turns brown when comes in contact with iron. It also forms black compounds with the tannins present in tomatoes or the spices which are used for product preparation.

Avoid prolonged heating and cool immediately to avoid over-cooking.

Pickles known to be good appetizers, aid digestion and pallate are edible products preserved and flavoured in a solution of common salt and vinegar. Spices and oil may also be added. There are a number of pickles very popular in India i.e. mango pickle, cauliflower pickle, lime and lemon pickles, ginger chilli pickle etc. But, some pickles like Sauerkraut are not very common in India but are very popular in European countries.

Jam : It is a product prepared by boiling to a suitable consistency, fruit pulp with sufficient quantity of sugar, acid and pectin so as to set and become firm enough to hold the tissues in position. About 45 parts of pulp are used with every 55 parts of sugar. The finished product should not contain less than 68 per cent total soluble solids.

Jelly : Jelly is prepared by boiling the fruit pectin extract with sugar in the presence of appropriate amounts of acid so as to set into a clear gel. A perfect jelly is transparent, devoid of haziness or any suspended material well set, but not too stiff and should have original flavour of the fruit. When cut it should retain its shape and show a smooth cut surface.

Marmalade : It is a fruit jelly like product in which slices of fruit or peel are suspended in the set gel. Mostly they are prepared from citrus fruits like oranges, lemons etc.

Canning : Process of preservation of various food stuffs including fruits and vegetables whole or in pieces, in sugar syrup or brine by heat processing them in hermetically sealed containers.

Drying/ Dehydration means the process of removal of water.

Drying : Removal of water (moisture) by using non conventional energy sources like Sun or wind.

Dehydration : Process of removal of moisture by the application of artificial heat under controlled conditions of temperature and / or humidity and air flow.

Freezing : Freezing is a process where temperature of food (fruits, vegetable etc.) is lowered down considerably below freezing point so that the water present inside the food undergoes change in state from liquid to solid (ice) and gets frozen immediately eg Frozen Pea. Water is immobilized and solutes are concentrated to reduce the water activity.

Principles of preservation : Combination of low temperature, low water activity, and pre-treatments like blanching, dipping in sugar syrup etc. stop (reduce) the growth and activity of microorganisms.

Theory of freezing : Freezing takes place in two main steps