What is freshness in fruits and vegetables? How does refrigeration play a role in maintaining the freshness? If so, is not the shrinkage due to dehydration, a measure of loss of freshness?

Many fresh vegetables and fruits retain their top quality only for a few days if they are not properly preserved. All green vegetables and fruits of high water content are best when fresh. If allowed to stand for a long period after gathering, they become wilted through loss of moisture by transpiration. The transpiration loss of water is one of the main processes that affect the commercial and physiological deterioration of fruits and vegetables after harvest. The moisture loss adversely affects the appearance, texture, flavour and weight of the products. Most notable effect of moisture loss is the softening of the tissues caused by the loss of turgidity. Storing them in the refrigerator can prevent this water loss. But the optimum storage temperature differs for vegetables and fruits.

Tropical vegetables and a variety of greens are in general susceptible to chilling injury. Therefore they must be stored at a temperature between 8 and 12 {+0}C. At this temperature the rate of metabolism of these vegetables is still considerably high, which reduces both the quality and storage life. So refrigerated storage of these vegetables should be well supplemented with Modified Atmospheric Packaging (MAP). Simple cost effective device is the use of perforated poly-packages that can maintain the desired oxygen and carbon dioxide levels within the packages.

Low temperature close to 0{+0}C with a preferred relative humidity of about 85% furnishes satisfactory conditions for commercial storage of fruits. Fruits stored in the home refrigerators tend to lose moisture. To prevent this the fruits must be kept in ventilated covered containers, enabling the circulation of air around sides, tops and bottoms of the fruits.

Source : The Hindu