Influence of fried and fried‐treated oils with different filter aids on rat health

Soybean, sunflower, palm and cottonseed oils were fried continuously at 180 ± 5 °C for 12 h. Fried oil quality was regenerated by adding individually Magnesol XL, diatomaceous earth and kaolin at 2% level, then stirring mechanically at 105 °C for 15 min and filtering. A set of nutritional experiments was conducted in which rats were administered standard diets containing non‐fried, fried and fried‐treated oils with various filter aids. The safety limits of the fried‐treated oils were recognized by measuring the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (AP), and levels of total lipids, total cholesterol, HDL cholesterol and LDL cholesterol of rat sera. Also, histopathological evaluation of rat liver tissues was microscopically done to detect any damage that might occur due to feeding rats on non‐fried, fried and fried‐treated oils. Administration of fried oils to rats induced significant rises in activities of ALT, AST and AP, and increases in the levels of total lipids and total cholesterol. The results demonstrate that there were non‐significant changes in sera levels of LDL and HDL cholesterol in rats fed diets containing various types of soybean, sunflower and cottonseed oils. Administration of fried‐treated oils to rat diets indicates that the activities of ALT, AST and AP and levels of sera constituents were similar to those of rats given non‐fried oils. Palm oil exceptionally behaved differently from the other oils. Palm oil raised sera total cholesterol and LDL cholesterol and lowered HDL cholesterol level. Histopathological examination of rat liver tissues indicated that changes paralleled the biochemical data. Copyright © 2006 Society of Chemical Industry