The behavior of a high-oleic acid sunflower oil used for 75 repeated deep-fat flyings of potatoes, with a fast turnover of fresh oil during frying, was evaluated by measuring the total polar content isolated by column chromatography. The total polar content increased in the oil from 3.6 + 0.1 (mean + SD) mg/100 mg unused oil to 7.6 + 0.4 mg/100 mg oil after being used in 20 repeated flyings, followed by a tendency to reach a near-steady state throughout the successive fryings. Further, the polar fraction was examined by high-performance sizeexclusion chromatography. Triacylglyceride dimers increased continuously from 0.18 _+ 0.01 mg/100 mg unused oil to 2.42 _+ 0.12 rag/100 mg oil at the 40th frying with no further significant changes. The amount of triacylglyceride polymers increased from 0.03 ± 0.00 mg/100 mg unused oil to 0.70 + 0.01 mg/100 mg oil at the 60th frying, but did not increase further with continued frying. Oxidized triacylglycerides also significantly increased from 1.13 -+ 0.06 rag/100 mg oil to 3.58 +_ 0.09 rag/100 mg oil at the 50th frying to reach a near-steady state in successive flyings. Diacylglycerides and free fatty acids levels, related to hydrolytic alteration, did not change from the starting oil after continued fryings. Data from this study indicated that repeated fryings of potatoes in high-oleic sunflower oil with a frequent turnover of fresh oil throughout the frying slightly increased the level of polar material in the fryer oil during the first flyings, followed by minor changes and a tendency to reach a near-steady state in successive flyings. JAOCS 72, 1513-1517 (1995).

Sets of 500 g of potatoes were discontinuously fried in 3 1 of palm olein using a zero turnover of fresh fat until a polar content of 25Oh was reached. A total of 90 fryings were required. Total alteration significantly increased (p<