Vacuum frying versus conventional frying – An overview*

Abstract

Deep‐fat frying of foods usually is carried out under atmospheric conditions at temperatures near 190°C. The problem that arises most often is excessive darkening or scorching of the product, even before the product is completely cooked. In addition, some of the oil decomposition products have been implicated in producing adverse health effects when fried oils degraded with continued use. Vacuum frying is a process that is carried out under pressures well below atmospheric levels (below 6.65 kPa). Vacuum‐fried products have higher retention of nutritional quality (phytochemicals), color is enhanced (less oxidation), and oil degradation is reduced compared to atmospheric frying. However, a de‐oiling mechanism is necessary to remove the excessive oil absorption at the surface of the product. The main objectives of this paper are to review the literature on vacuum frying specifically on the effect of vacuum frying operating conditions such as pressurization and de‐oiling mechanisms on the final product oil content. Product quality attributes as affected by atmospheric and vacuum pressures and fundamental modeling of the process are also discussed in this article.