Estudo da stabilidade termo-oxidativa de óleos comestíveis ricos em ácidos graxos insaturados e blends

Abstract

avras-chave: ácidos graxos poli-insaturados, alimentos nutraceuticos, degradação oxidativa. ABSTRACT Vegetable oils are widely consumed lipid foods worldwide. They are used in a variety of ways, both in the in natura form and in sauces and fatty foods in general. Oils such as soy, corn, canola and sunflower oils are rich in polyunsaturated fatty acids (PUFAs) and they are used in cooking, cooking and mainly in frying. Olive oil, oil extracted from the olive tree (Olea europaea), rich in oleic acid, a monounsaturated fatty acid (AGMI), although not a source of the unbeatable omegas-3 and omegas-6, it is regarded as a food that brings enormous benefit to human health, being part of the Mediterranean diet. Foods that bring health benefits when consumed regularly are considered functional foods and in this context are inserted oils rich in unsaturated fatty acids AGMI and AGPI. In this work, the oils of canola, sunflower, corn and soybean were used, oils rich in PUFAs and widely used in Brazilian cuisine, and the oils of the moringa, tomato and papaya seeds, unconventional and unknown oils of the great consumers in the preparation of compositions with high levels of PUFAs to be used as functional foods. The physico-chemical characterization, the thermal and oxidative properties of the oils and compositions were determined by conventional analytical analysis by accelerated methods of evaluation of Rancimat oxidative stability and Schaal's test by the techniques Gas Chromatography (GC), Nuclear Magnetic Resonance of Hydrogen 1 H-NMR) and Infrared (IV). The results indicated that moringa and papaya oils´ are invaluable sources of omega-9 AGMI. Moringa oil, for example, had oleic acid content similar to that found in olive oil, indicating a great thermal and oxidative stability. Tomato oil on the other hand showed a high content of omega-6 linoleic acid (61.77% by mass), a much higher value than that found in soybean oil (54.75% by mass). The evaluation of the thermal and oxidative behavior of the oils by the 1H and IV NMR revealed that in omega-6 rich oils an expressive decomposition of these fatty acids occurred.With respect to oils rich in omega-9 oleic acid, all the applied procedures showed a high resistance of these oils, however, also signs of degradation were observed when heating the frying temperature (180ºC) for 24 hours with intervals.The data obtained in the development of this research up to the present show that the consumption of oils rich in PUFAs although they bring benefits to the human organism, their consumption requires measures that are routinely not taken into account by the consumers as much for lack of information on the part of the control authorities of the food industry and by the manufacturers of these foods. In any case we feel that more information about the consumption of oils is essential so that the consumer has the benefits and not the harms of these foods. With the help of gas chromatography, it is possible to verify the omega-6 and 9 levels of the oils analyzed, in which the highest omega-6 content is in the 61.77% tomato oil and the omega-9 is in the papaya oil 64.84%. There was a significant increase in the induction period of the oils the blends were made, since the addition of omega-9 rich oils improved thermooxidative stability.