Quality changes of oils during deep-fat frying of food from animal origin

U ovom radu praćene su degradacijske promjene suncokretovog ulja i ulja kukuruznih klica tijekom prženje namirnica životinjskog porijekla. Istraživanje je obuhvatilo prženje 40 šarži ribica tijekom 5 dana a uzorci za analizu uzimani su nakon svake četvrte ispržene šarže. Cilj istraživanja bio je utvrditi vremensku granicu nakon koje se ulje odbacuje te usporediti kvalitetu dvije istraživane vrste ulja. Procjena degradacije određena je određivanjem jodnog, peroksidnog i kiselinskog broja, udjela polarnih spojeva i oksidiranih masnih kiselina te senzorskom procjenom. Količina oksidacijskih, hidrolitičkih i polimerizacijskih razgradnih produkata formiranih tijekom procesa prženja, rasla je proporcionalno s vremenom prženja u obje vrste ulja.In this work we have investigated the main changes in two kinds of frying oils due to nature of the the fried food. Fourty frying cycles of fried fish were carried out each day during five days, and samples for analysis were taken after each fourth cycle. The aim of this study was to establish the deterioration of commercial sunflower oil and corn oil during deep-fat frying of food and to determine its discard point. The degradation of both kind of oils was evaluated by determination of iodine value, acid value, peroxide value, content of polar compounds, content of oxidised fatty acids and sensory analysis. Amount of oxidative, hidrolytic and polymerized degradation products formed during deep fat frying of fish increased with time of frying and number of frying cycles