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Freezing methods for food are convenient and easily applied. Since the invention freezing is one of the few methods which allow the preservation of food attributes such as taste, texture whilst maintaining the nutritional value. Frozen products are very similar to the original fresh product, particularly if good handling and safety practices are utilized both before and after freezing. Retention of quality and safety are better achieved when frozen foods are kept at maximum temperatures of -18 °C or even lower. At these temperatures micro-organisms cannot grow and any deteriorative reactions take place at very slow rates. Frozen agricultural products can retain their quality over long storage periods if the correct procedures are applied.

In developed countries the freezing of foods represents a major industry. However, in developing countries it is hardly developed. The frozen foods industry is considered expensive, mainly due to the high initial investment cost for the equipment, but the freezing process and storage costs per se only represent about 10 percent of the total cost of production. In many developing countries the cost of energy for industrial use is relatively high, highlighting the need for governments in developing countries to consider establishing lower energy tariffs in order to promote agro-food processing industries such as freezing.

In this technical manual fundamental knowledge and socio-economic issues concerning freezing are presented, with coverage extending from large-scale freezing to freezing on a micro- or small-scale. The manual consists of five chapters containing basic concepts and operations to give a better understanding of the application of freezing preservation. Chapter one presents an introduction to freezing technology, emphasizing the importance of the frozen food industry with general recommendations on the application of technology for fruits and vegetables. Chapter two gives specific examples of freezing preservation applied to selected food prototypes. Chapter three focuses on raw material selection and freezing equipment. Chapter four presents general recommendations regarding final product quality whilst Chapter five presents cost estimates and product prices for selected frozen products.

The freezing of fruits and vegetables on a small scale could be developed in many developing countries, by using the standard household freezer. It is also a good option for potential entrepreneurs interested in developing this technology which is often technically and economically feasible under a variety of circumstances.

Agricultural and Food Engineering Technologies Service
Agricultural Support Systems Division
FAO of the U.N.

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