Define the Sun and Solar Drying Method?
The make use of solar energy to preserve the food items is mainly the oldest form of food reservation and is still practiced today for foods like raisins. Sun and solar drying of fruits and vegetables is a cheap process of preservation as it uses the natural resource/ source of heat that is sunlight. The benefits of the process are that the energy is free, renewable and non-polluting. Conversely, the drawbacks are that it can be very labour intensive, suffers from a lack of control and is prone to deterioration by biochemical reactions or microbiological or insect infestation. Sun/solar drying method can be utilized on a commercial scale also at the village level provided that the climate is hot, relatively dry and free of rainfall during and right away after the normal harvesting period. The fresh crop should be of good quality and as ripe (mature) as it would require to be if it was going to be utilized fresh. Note, poor quality produce cannot be employed for natural drying. Different lots at various stages of maturity (ripeness) must NOT be mixed together; this would result in a poor dried product. Few varieties of fruit and vegetables are better for natural drying than other; they must be capable to withstand natural drying without their texture becoming tough that is why they are not difficult to reconstitute. Some varieties are unsuitable, as they have irregular shape and there is a lot of wastage in trimming and cutting such varieties.
As common rule plums, grapes, figs, dates are dried as whole fruits without cutting/slicing. Some fruit and vegetables, in specific bananas, apples and potatoes, go brown very fast when left in the air after peeling or slicing; this discoloration is due to an active enzyme known as poly-phenoloxidase. To prevent the slices from going brown they must be kept under water until drying can be started. Salt or sulphite in solution provides better protection. Though, whichever method is used, further processing should follow as soon as possible after cutting or slicing.