Avaliação de estratégias de estabilização oxidativa do farelo de arroz integral

Abstract

The rice bran is obtained from the polishing of husked rice to produce white rice and, despite its high content of protein and vitamin, this by product is still almost entirely used to animal nutrition and less used by the food industry. Due to the large amount of bran produced, there is a big effort to increase the oxidative stability of this material. The aim of this study was to evaluate the stability of rice bran on the known conditions of humidity and temperature and then, propose a procedure for its stabilization, affordable and easily applicable. Therefore, various treatments were employed, such as physical processes (pelleting and irradiation), synthetic antioxidants as well as natural antioxidants. The rice bran was stored for 90 days and analyzed for its chemical composition, acidity and peroxide value. The values of acidity and peroxide value were similar to those found in the literature. The acidity and peroxide value increased during the storage time for almost all treatment combinations. The start and final acidity values of rice bran treated with natural and chemical antioxidants were higher than those obtained from physical processes. The lowest initial acidity values were 7.10, 6.09, and 4.36% for natural antioxidants, chemical antioxidants and physical processes, respectively. The highest total acidity value was observed for natural antioxidants (17.58%) and the lowest, for the treatment with chemical antioxidants combined with pelleting (9.12%). The results indicated that the stabilization of rice bran is affected by environmental conditions such as temperature, relative humidity, and storage time. The chemical composition of rice bran is affected by rice origin, species, harvest period, processing and type of soil. Irradiation and pelleting processes proved to be satisfactory and efficient for the oxidative stabilization of the rice bran in the food industry.