Eureka! Institutional Repository

This study examined the effects of repeated potato frying and of prolonged oil heating on selected chemical properties of the frying medium. Three series of repeated frying experiments (of 45 frying batches each, lasting 22.5 h each) were conducted where the oil type (sunflower, palm and extra virgin olive oil) were varied. In addition, three series of prolonged heating experiments ( each lasting 22.5h) were performed using the same oil types and following the same time – temperature profile of the frying experiments but without the addition of potatoes in the fryer. This allowed quantitative comparisons between potato frying and oil heating experiments in order to assess the effect of food on oil chemical deterioration. The chemical profile of all three types of oil change significantly during frying. In the case of palmoil, the main generated products were those of thermal and oxidative polymerization,while in sunflower and extra virgin olive oil besides these products, products of lower molecular weight than triacylglycerolsobtained by hydrolysis and oxidation reactions. With prolonged heating, sunflower,palm and extra virgin olive oil underwent polymerization only.