r o y o , C . C u e s t u *, 1 . M . S r i n c h e z -M o n t e r o a n d F. J . S d n c h e z -M u n i z
Thermoxidative and hydrolytic alteration of palm olein (43.4 % oleate) used in sixty repeated and intermittent deep-fat fryings of potatoes (without turnover of fresh oil) were measured by column and high performance size exclusion chromatography (HPSEC). Successive fry- ing of potatoes increased the level of total polar component in the oil from 9.27 k 0.07% (mean f SD) to 18.16 f 0.21%. Compounds related to thermoxidative alteration also increased significantly in the oil used 60 times to fry potatoes. Triacylglycerol polymers increased from 0.12 f 0.01 mg/100 mg oil to 1.56 f 0.02 mg/100 mg oil. Triacylglycerol dimers increased from 1.02 f 0.03 mg/100 mg oil to 5.00 f 0.05 mg/100 mg oil. Oxidized triacylglycerols also increased from 1.12 f 0.22 mg/ 100 mg oil to 5.25 f 0.11 mg/100 mg oil. Nevertheless, diacylglycerols and free fatty acid levels related to hydrolytic alteration did not increase with continued fryings. Thermoxidative alteration took place instead of the hydrolytic process. However, despite the increase of polar material during frying, the palm olein performed satisfactorily in this frying experiment taking into account that the null turnover of fresh oil instead of a fast turnover of fresh oil during the performance of fryings would increase the deterioration of the oil. '' G. Billek, in: The Role of Fats in Human Nutrition, edited by E B. Paddley, 1. Podmore (in collaboration with 1. I!