It is part of age-old human experience that food remains in fresh condition longer in cool than in warm weather. Hence it is not surprising that one of the first applications of mechanical refrigeration was to cool perishable food to prolong their storage life. It was claimed in 1968 that there were 2823 types of frozen foods, including 639 types of frozen vegetables, 446 frozen deserts, and 448 types of frozen seafood. It is further stated that 58% of the volume of frozen foods is fruit juices and vegetables. It is also said that frozen soups account for 11.4% and baked goods for 10.1%. Before freezing, it is necessary to blanch the product to destroy enzymes, which would result in off-flavours and consequent quality deterioration. Rapid freezing is important, since just as with ice cream, it results in a smoother product having smaller ice crystals and a more natural body and texture. In the first freezing systems the product was frozen by being subjected to high velocity air at temp. as low as 400F. The next important was that of the birds eye system, in which the product was frozen extremely rapidly, by being clamped tightly between very old refrigerated plants at – 20 to – 400F. This gave very rapid heat transfer and quick cooling resulting in marked improvement in the quality of both and vegetables the details of the system vary somewhat with the product the rate of freezing depends upon the size of packages but in usually on the order of ½ hr to 1 hr. Calculation of Refrigeration Requirements: Fruits and Vegetables are high in water content, and are absorbed much refrigeration. FREEZING Many vegetables are seasonal crops, abundant at certain times of the year, and not readily available at other times of the year. In order to extend availability all year round, methods of preservation are needed. These methods may alter the characteristics of the vegetables; some to a small extent, some to a large extent. They may also be effective over different time periods. Some extend shelf life by only a few weeks, some give a shelf-life of many months. The changes in the tissue characteristics consequent upon the preservation technique may be more market where long storage lives are required. for long-term storage, extending from months to years, canning (in which product is placed in a hermetically sealed container, and then heated sufficiently to achieve sterility) and freezing (in which product is cooled down to temperatures below – 200C and maintained at these temperatures) are the primary preservation techniques. Freezing is often preferred over canning, because the alternations to the tissues, such as softening and colour changes, may be less marked. Preservation by freezing makes use of the phenomenon that rates of chemical change are generally reduced at lower temperatures. Rates of physical change, too, may be reduced at sufficiently low temperatures, so that a product may be stored at low temperatures for extended periods without there being too much change in its properties compared to those it had at the commencement of the storage period. The freezing process itself, however, may result in change. There are commodities, such as lettuce, preservation of that particular commodity. It is generally true that the lower the temperature of storage, the slower the rate of change in properties. Because freezing involves the separation of some of the water in the product as ice, with consequent increase in the concentrations in the unfrozen phase, and potential crystallization or precipitation of other components, the rate of deterioration may be affected by factors other than the temperature linked slowdown. Higher solute concentrations may induce increased rates of change in some chemical processes (1). Also, low temperatures may enhance the rates of some crystallization processes. The rates of change in frozen systems could then be a complex function of temperature. There may be a temperature region with enhanced rates of change just below 00C in some systems. However, at sufficiently low temperatures, of rates of change will reduce. This is illustrated schematically in Figure. The upper line illustrates rate enhancement due to freezing. The lower line illustrates rate inhibition due to freezing. The centre line represents the rate to be expected on the predictions of the Arhenius rate expression. The arhenius expression in inappropriate for use in frozen systems, as it does not allow for the complex changes, which accompany the separation of crystalline ice, but assumes the system stays on uniform phase. It has recently been shown that, in systems containing ice, the temperature dependence of the kinetics in the unfrozen phase may better be described by an equation, known as the Williams-Landel-Ferry equation, which describes the temperature dependence of kinetics in rubbery systems. To-day frozen foods are available in retail and institutional outlets over all areas of the country. The total annual commercial production is estimated to be more than ten billion pounds. Obviously, what is produced must be marketed. To day some 250,000 retail stores have frozen food departments and 75 percent of the Industry out put is sold through supermarkets. The distribution channels of produce run through a long chain of middlemen by and large the processing industry gets its few materials from the maindis or wholesales markets. There are of course a few large units who have their orchard and farms. But even these depend extensively on mandis. The industry does not get preferential treatment in credit allocations. The raw materials used by it being highly perishable, the financial reckoning of security is extremely conservative. However, finished products are subjected to the usual norms for purposes of bank financing.