RELATIONSHIP BETWEEN CHEMICAL AND PHYSICAL INDEXES AND COLUMN AND HPSE CHROMATOGRAPHY METHODS FOR EVALUATING FRYING OIL

Standard chemical and physical indexes, such as color index, acid valu e, and K-270 were compared with the polar content and the specific the rmoxidative and hydrolytic compounds originated during 75 potato fryin gs with sunflower oil. The color index, acid value, K-270 and total po lar content showed a significant increase (p < 0.05) after the first 3 0 fryings, followed by a tendency of the last three indexes to reach a near-steady state. Triglyceride polymers and triglyceride dimers show ed a significant increase (p < 0.05) after 30 fryings, while the oxidi zed triglycerides were not increased significantly after 30 fryings. T he amount of diglycerides and free fatty acids related to hydrolytic a lteration did not change significantly throughout the frying operation s. The significant correlations between acid value and total polar con tent, triglyceride dimers, triglycerides polymers and oxidized triglyc erides, or between color index and polar content and triglyceride poly mers or between K-270 and triglyceride polymers indicate that these si mple and standard methods can be applied and they are as useful as mor e specific methods of evaluation in the monitoring of frying operation s, provided that initial values of all of these indexes are available.