Impact of Freezing on Food - Essay Example

While food preserved in many home freezers are held at -10C, commercial freezers are under -18C (0 degrees Fahrenheit). Long-term freezing for commercial purpose requires a constant temperature of -18 C or less. At this low temperature, the growth of micro-organisms is more or less stopped. Deteriorative microbial reactions will still occur, but over a much longer time. In addition, deteriorative enzymatic reactions will still take place during frozen storage (Omafra Staff n. pag. 2005). Though freezing is an effective method of food preservation, freezing can adversely affects the texture of many foods.

It should be noted that the texture of nearly all foods is damaged by thawing and re-freezing. It is also important to understand the technology behind freezing. Since water expands when it freezes, cell walls in food especially fruits and vegetables having high water content are often ruptured, resulting in food that is limp or pulpy when thawed. The high starch content in some of the vegetables reduces such damage. Besides less damage is also done if the food is frozen immediately. Hence unfrozen food should be placed in the coldest areas in the refrigrator (Wikipedia n.pag. 2007).

Freezing has been a key technology in bringing convenience foods to homes and restaurants. It causes minimal changes in the quality of food in terms of size, shape, texture, color, flavor and microbial load. This is assuming that the freezing process is carried out properly. A key factor during food freezing is how fast we freeze. When food is frozen slowly, the ice crystals formed will be large these large ice crystals are undesirable as they will damage the cell structure especially the non-vegetarian foods like meat and fish.

Hence ice formation will result in poor texture and excessive dripping upon thawing. Frozen food must be maintained at the proper temperature at all times. For instance if we take the case of ice creams, it is very sensitive to fluctuations in temperature. In cases of temperature fluctuation, it can cause a defect called sandy texture and the ice cream will in fact taste grainy, as if it contained come kind of granules. These granules are nothing but lactose crystals which naturally occur in milk that is generally dissolved.

Temperature fluctuation, however, will cause lactose to crystallize out, imparting sandiness (Institute of Food Technologists n.pag 2005).There are also studies that have done comparative studies on muscle from fresh (unfrozen) and freshly frozen chickens. The results showed that freezing caused small, but detectable changes in eating quality and also that these changes in muscle proteins during freezing depended on freezing rate. Slow freezing resulted in a larger loss of drip on thawing, a larger loss of nitrogenous constituents and nucleic acid derivatives to the drip, and a larger loss of water-holding capacity of meat, than fast freezing.

Besides, slow freezing, as compared to fast freezing, increased proteolysis and caused a greater decrease in the adenosine-triphosphatase (ATP) activity of myofibrillar proteins. In addition difference in taste was also noted. The results of this study suggest that rapid freezing preserves the integrity of muscle proteins to a greater extent than slow freezing and there by the quality of fo