Effect of Re-Use of Frying Fat From Selected Food Service Establishments on the Lipid Components of Fried Shrimp

The effect of re-use of frying fat was studied in five types of food service establishments. Samples of shrimp were obtained in quantity and fried in each establishment during two complete uses of fat. Analyses of selected samples of frying fat and shrimp lipids included: viscosity of frying fats, silicic acid column fractionation of raw and fried shrimp lipids, silver-nitrate thin-layer chromatography of frying fats and shrimp glycerides, and gas-liquid chromatography of frying fats, shrimp glycerides, shrimp phospholipids, and thin-layer sub-fractions of frying fats and shrimp glycerides. An attempt was made to relate changes in lipids to frying practices in the food service establishments.

Changes occurring during re-use of fat were not pronounced. Lipid changes noted in frying fats were an increase in viscosity and some decrease in poly-unsaturation, probably reflecting the changed composition of the absorbed frying fats. None of the changes appeared sufficient to warrant any consumer concern regarding the use of commercially fried foods.

In contrast to lipid data available for land animals, the results of this study indicated that the shrimp glycerides were more unsaturated than the shrimp phospholipids.