Rice bran is an industrial by-product, representing 5-8% of the grain. It is rich in proteins, lipids, diet fibers and anti-oxidant compounds, such as tocopherol, tocotrienol and oryzanol. Rice bran is a natural source of lipids, containing more than 25% of oil, especially unsaturated fatty acids. As a source of essential fatty acids, the high content of lipids in rice bran limits its use: due to the possibility of rapid rancidity there is a necessity for stabilization, immediately after production. In this work, the stability of the rice bran treated by four stabilization processes was evaluated during four months of storage: POR: non-stabilized polished rice bran; PORTO: toasted polished rice bran; PORS: cheese-whey-stabilized polished rice bran; PAR: non-stabilized parboiled rice bran; PARTO: toasted parboiled rice bran; PARS: cheese-whey-stabilized parboiled rice bran. We evaluated the alcohol-soluble and water-soluble acidity of rice bran stored at 48 degrees C, every week, for four months. The process of cheese-whey addition increased the content of calcium in bran. Parboiled rice bran (PAR) was the most stable sample during the storage, suggesting that the parboiling gives greater stabilization to the bran. (c) 2005 Elsevier Ltd. All rights reserved.