Frying is one of the oldest and cooking methods in existence where an edible fat heated above the boiling of water serves as the heat transfer medium. Deep fat fried products, like potato chips, French fries, doughnuts, extruded snacks, fish sticks, and the traditional-fried chicken products, have been most popular for years because of their unique flavor texture combination.
However, high oil uptake and many adverse reactions take place during deep-fat frying because of high temperature.
Vacuum frying is a reasonably new technology which uses lower pressure and temperature rather than atmospheric deep-fat frying to improve the quality attributes of food products. It is working in low temperatures and of the minimum oxygen content. Due to the pressure lowering, the boiling points both of the fat and moisture in the foods are lowered. Vacuum frying is an alternative technique to improve the quality of dehydrated food (Song et al., 2007).
Vacuum frying technology has been successfully applied in fruits, vegetables, fish and wheat-based snacks, including apple, apricot, carrot, grass carp, gold and green kiwifruits, mushrooms, potato and shallots. There was a wide range of vacuum pressures used ranging from 1.33 to 90 kPa with more than half of the processes carried out at lower than 10 kPa.
