PH losses in vegetables and fruits is a key area of concern. But the magnitude of pH losses can be minimised by proper cultural operations, harvesting, transportation and storage facilities.
As far as storage is concerned, through the establishment of cold storage and related amenities at the growers' and retailers' level, there is likely to be greater scope for fruit and vegetable processing industry. In this regard, presently, mango, pineapple, citrus, grapes, tomatoes, peas, potatoes, and cucumber are being processed on a major scale.
There are about 4,000 small- and large-scale processing units in the country which process only about 2.5% of the total fruits and vegetables as against 40-85% in developed countries - Malaysia - 83%, Philippines - 78%, Brazil and USA - 70%.
In India, there is a vast scope for growing fruits and vegetables throughout the year in one or other part of the country because the climatic conditions are highly suitable for growing various types of fruits and vegetables.
Fruits and vegetables are highly perishable but constitute the most important commodity for human diet due to their high nutritional value. They are the cheapest and other source of protective food supplied in fresh or processed or preserved form throughout the year for human consumption. Hence the national picture will improve significantly.
Further, fruits and vegetables are available in surplus only in certain seasons and depending on different regions.
In peak season, due to improper handling practices, marketing, and storage problems around 20-25% fruit and vegetable are spoilt in various stages.
Fruits and vegetables are living commodities as they respire. Hence, proper post-harvest management handling and processing are required in horticulture crops.
A variety of fresh fruits and vegetables in India can be made available in plenty due to favourable agro-climatic situations. Hence there is no dearth of raw material for processing.
The product profile being developed in India at present is limited to few fruits and vegetables. For example: mango, pineapple and grapes. But there is wider potentiality for processing of papaya, sapota, banana, jack, guava, aonla, carambola and other minor fruits.
Similarly there is greater scope for processing cauliflower, carrot, bitter gourd, onion, garlic, watermelon, muskmelon and so on.
Importance of Post-Harvest Technology
Proper handling, packaging, transportation and storage reduce the post-harvest losses of fruits and vegetables. For every one per cent reduction in loss will save 5 million tons of fruits and vegetables per year.
Processing and preservation technology helps to save excess fruits and vegetables during the glut season (off-season).
The technology has become a necessity to improve food safety and strengthen nations' food security. The technology helps to boost export of agricultural commodities in the form of preserved and value-added products.
Presently, mango, pineapple, citrus, grapes, tomatoes, peas, potato and cucumber are being processed on large scale.
Principals and methods of preservation of fruits and vegetables
Preservation means protecting foods against spoilage, but scientifically it may be defined as a science which deals with the process for prevention of decay or spoilage of the food.
In other words, just controlling the physical, chemical or microbial changes in the foods is called preservation. The physical changes cover colour, flavour, texture, taste and so on. Also chemical changes related to carbohydrates, fats, proteins, vitamins and minerals. AS also microbial changes are due to attack of mould, yeasts and bacteria.
Need for food preservation
Food needs to be preserved to increase shelf life and augment supplies. Seasonal fruits are available throughout the year. With preservation, it can add to the variety of the diet. It saves time by reducing preparation time and energy as consumption of fuel is brought down. From a commercial perspective, it helps to stabilise the prices of the food in the market.
Principles of preservation
There are three main principles in preservation which help as they delay the microbial decomposition of the food. They stop shelf-decomposition of the food and prevent the damage by insects, animals, mechanical causes and so on.
Prevention of microbial decomposition of the food helps to keep out the microorganisms by Asepsis Filtration and creation of an anaerobic condition. Exposing to high temperatures allows killing of microorganisms.
Asepsis prevents the entry of microorganisms by maintaining general cleanliness, while picking, grading, packing and transporting of fruits and vegetables, improves their quality and enables to ensure superior quality of product prepared from them.
Fruit juice, soft drinks, wines etc. enter through bacteria-proof filters, which are made of asbestos pad or unglazed porcelain type of materials.
These filters contain microorganisms and allow water or juice to percolate though with or without pressure.
Anaerobic conditions can be maintained by replacing the oxygen carbonation by evacuating the sealed container of fruit juice for instance. Another is the use of oils from top of the food or pickles. Besides, exposing at high temperature, fruits can be preserved using the process of canning because it prevents spoilage and inactivates the enzyme present in the food from getting spoilt.
In case of irradiation, the food is exposed to radiations to kill the microorganisms by ionising and non-ionising radiation where the food is exposed to electromagnetic frequencies ranging from low frequency electro-magnate to high frequency which is gamma rays that destroy the microorganism present in the food.
The delay of shelf decomposition is done by destruction or by inactivating the enzyme through processes like blanching. The procedure delays the non-enzymatic chemical reactions. Blanching helps in softening the tissues to facilitate packaging. It helps to preserve the original colour and flavour apart from destroying certain enzymes which are undesirable. Other methods are elimination of the air mostly for vegetables. Efforts to remove microorganisms, astringent taste and toxins are also done to protect the food gamma deterioration caused by exposure to the air.
