Foaming Tendency of Frying Oil by Egg-frying

Abstract

Foaming tendency of frying oil during egg-frying and of heating oil with soya lecithin or egg yolk lecithin were investigated. The method was to determine the foam height for a series bubbling when a potato slice (5 mm in diameter × 5 mm in thickness) was thrown into bottomless test tube in the frying oils. During egg-frying, phospholipids of the egg migrated to the frying oil. As the results an increase of foaming tendency of the oils were observed. The higher the migration of phospholipids was, the higher the foaming tendency of the oil was. Added soya lecithin or egg yolk lecithin promoted the foaming tendency of oil during heating, but the addition of choline and phosphoric acid (a component of phospholipids) showed no effectiveness. Hydrogenated Soya lecithin (100%) showed larger foaming tendency of oil than unhydrogenated soya lecithin. Oxidation stability and residual percentage of tocopherol after egg-frying was higher in the oil with egg-frying than in the heating oil without egg-frying.