Quality control during repeated fryings

Most of the debate is about how the slow or frequent turnover of fresh fat affects the deterioration. of fat used in frying. Then, the modification of different oils used in repeated fryings of potatoes without or with turnov er of fresh oil, under similar frying conditions, was evaluated by two crit eria: by measuring the total polar component isolated by column chromatogra phy and by the evaluation of the specific compounds related to thermoxidati ve and hydrolytic alteration by High Performance Size Exclusion Chromatogra phy (HPSEC). The results indicate that with frequent turnover of fresh oil, the critical level of 25% of polar material is rarely reached, and there a re fewer problems with fat deterioration because the frying tended to incre ase the level of polar material and thermoxidative compounds (polymers and dimers of triglycerides and oxidized triglycerides) in the fryer oil during the first fryings, followed by minor changes and a tendency to reach a nea r-steady state in successive fryings. However, in repeated frying of potato es using a null turnover the alteration rate was higher being linear the re lationship found between polar material or the different thermoxidative com pounds and the number of fryings. On the other hand chemical reactions prod uced during deep-fat frying can be minimized by using proper oils. In addit ion the increased level of consumers awareness toward fat composition and i ts impact on human health could had an impact on the selection of fats for snacks and for industry. In this way monoenic fats are the most adequate fr om a nutritional point of view and for its oxidative stability during fryin g.