Deep frying is one of the oldest, quickest and easiest ways of heat treating food, the problem of which is the rapid deterioration of the quality and stability of the oils during deep frying. The aim of this work was to determine the suitability of alternative oils (peanut, hemp, flaxseed and sesame oils, sunflower as control) in terms of their sensory quality and fatty acid composition after multiple, three consecutive deep-frying of meatballs in the model system. The nutrient composition in fresh beef meatballs (NIR) and weight loss after each frying were measured. Smoke point of used oils, as well as fatty acid composition (GC) and thiobarbituric acid number (TBA, spectrophotometric) were determined on oils and meatballs after three consecutive frying, additionally oils were also sensory analysed (descriptive analysis). The stability of the used oils depended on the smoke point of the oil (sesame 164 °C, hemp 171 °C, flaxseed 175 °C and peanut oil 184 °C) and the TBA number, which increased after consecutive frying in oils and meatballs (peanut and sesame < sunflower < flaxseed and hemp oil). The TBA number was related to the fatty acid composition of used oils (in general, a higher proportion of polyunsaturated fatty acids means poorer stability during frying). Consecutive deep frying changes the fatty acid composition of oils and meatballs. After the first frying the proportion of monounsaturated fatty acid in frying oils increases and the proportion of polyunsaturated fatty acid decreases. After successive frying, the sensory properties of the used oils deteriorate. Not all types of cold-pressed oils are equally suitable for deep-frying; regarding suitability, the oils follow each other in the following order: sesame > peanut > sunflower oil > hemp > flaxseed oil. From a nutritional and health point of view, flaxseed and hemp oil are the most suitable for consumption, of course if used cold and not in harsh heat treatment processes.
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