Lecitina de arroz (Oryza sativa): caracterização físico-química, nutricional e estabilidade

Abstract

The lipid fraction of rice bran contains several compounds that stand out not only for their important role in health, but also for their application in industry as food additives. Tocopherols, tocotrienols and γ-oryzanol have antioxidant properties capable of reducing the risk of several chronic diseases; in addition to the profile of unsaturated fatty acids, which are able to reduce cholesterol and blood pressure. On the other hand, among the phospholipids, lecithin stands out for having remarkable emulsifying and stabilizing properties. However, studies with lecithin come from sources such as soy, which have allergenic compounds. With this, this project proposed the study with lecithin extracted from rice, a non-allergenic raw material with interesting nutritional properties. Thus, this work aimed to evaluate the physicochemical and nutritional properties of natural and bleached lecithin obtained from rice, as well as to study its stability during storage. Lecithin samples were obtained from the refining of oil extracted from rice bran at Indústria Rio-grandense de Óleos Vegetais Ltda. The lecithin bleaching process consisted of the application of hydrogen peroxide, which acts directly on the pigmentation, making it lighter. For the quality control of lecithin, 12 batches were evaluated in relation to physicochemical parameters (acidity index, insoluble in hexane, insoluble in acetone, peroxide and moisture content). Among these batches, 5 batches of natural lecithin and 2 batches of bleached lecithin were approved for marketing. In addition, it was possible to observe that the bleaching of lecithin resulted in an increase in physicochemical parameters, reduction of moisture and depigmentation of lecithin. Regarding nutritional compounds, natural lecithin showed a greater tendency to accumulate phospholipids, tocopherols and tocotrienols (α- and γ-), palmitic, stearic and linolenic acids, while bleached lecithin stood out for accumulating γ-oryzanol, δ-tocotrienol and oleic and linoleic acids. Lecithin was stored for 230 days, being possible to guarantee its stability for 45 days in sun and shade, and for 90 days in controlled conditions of temperature and humidity, mainly due to the impact on the peroxide index. However, it was possible to guarantee the stability of the lecithin in a sealed container for 360 days