Avaliação da estabilidade de óleos e gorduras

Abstract

In Brazil, the most important vegetables are soya and palm oils. Vegetable fat is widely used in the food industry, in cakes, cookies, ice creams and creams, while pork fat is a product that is entering the market as another alternative for the consumer. The composition of saturated and unsaturated fatty acids, as well as their amount in each product, may influence oxidative stability which could decrease the storage time of the oil or fat. Considering this, the present work had as objectives to evaluate the saponification, iodine (in natura and after aging at 60 ° C for 10 days) and to determine the oxidative stability through the greenhouse test, with measurements of acidity and peroxide indexes at regular intervals of 2 days, during the storage of 10 days at 60 ° C. The analyzes for the evaluation and determination of the indices were carried out in soybean oil (OS), palm oil (OP), hydrogenated vegetable fat (GV) and swine fat (GS). The results were submitted to analysis of variance (ANOVA) and to the Tukey test at the 5% level of significance. From the results obtained for the saponification index, in spite of the treatments OS, GV and GS were above the limit established by the legislations, of 190 - 200mg KOH / g. For the iodine index, all the treatments were below the permitted values in the legislations, with soybean oil being the most discrepant value required by ANVISA regulations. The acidity indexes were all within the values stipulated by the standards, so the results obtained of acidity were not used to determine the oxidative stability, since it has to present a critical point of deterioration to finalize the time counting. Regarding peroxide analysis, all treatments showed an increase in the index over the storage time. From the analyzes carried out, it was possible to conclude that the vegetable fat and the soybean oil are more stable than the other treatments studied. Possibly, the refining process and the use of antioxidants in industrial processing, contributed to this moderate result in oxidative deterioration.