determination of the physicochemical changes in the different vegetable oils after fat-product interaction during frying process

Determination of changes in physicochemical properties of different vegetable oils (sunflower, corn, hazelnut, palm, and olive oils) was aimed after the frying process with different frying material used (potato and pepper). the increase in free fatty acid content, peroxide value, viscosity and polar compound formation of oils was observed, while the reduction of the polyunsaturated fatty acid content of oils was detected with the increase of frying time. the minimum increase of free fatty acid content was determined in sunflower oil (for fried pepper %0.23; for fried potato %0.22), while the best result of peroxide values for both of frying samples was found in olive oil (for fried pepper 2.49 meq o2/kg; for fried potato 4.11 meq o2/kg oil). the highest increase of total polar compound was also ascertained in sunflower oil (for fried pepper %4.50; for fried potato %5.00). the increase of frying time caused a decrease of l* and a* values of oils except for olive oil and increase of b* values. the effect of frying oil or material and frying process time on physicochemical properties of oils was found statistically significant (p<0.01).