Improved shelf-life of rice bran by domestic heat processing and assessment of its dietary consumption in experimental rats

Rice bran, a valuable byproduct of the rice milling industry, in spite of being a rich nutrient, has limitations in food application, being highly susceptible to rancidity caused by the inherent enzyme lipase. In the present investigation, three simple heat treatment procedures, namely pan roasting, pan roasting with oil and microwave roasting, were examined to extend the shelf-life of three varieties of rice bran. In the heat-treated rice brans, the increase in free fatty acid content at the end of a 3-month storage period was 1.6- to 2.5- fold as a result of heat treatment, while it was 12- to 23-fold in the absence of heat treatment. In an animal experiment, pan-roasted rice bran was fed to rats at 5% and 10% levels to study the palatability and safety of its consumption. The mean food intake was slightly higher in the 10% rice bran group (13.57 +/- 0.2 g compared to 12.31 +/- 0.52 g in control). Rats in the 10% rice bran group gained higher body weight when compared to the control group, which can be attributed to the higher food consumption by these animals. Dietary rice bran did not have any adverse effect on any of the hernatological parameters. Serum protein level was similar to that of the control group except for an increase in serum albumin in rice bran-fed groups, which is indicative of liver sufficiency in rice bran treatment. The weights of liver, kidney, heart and testes were not affected by rice bran either at the 5% or 10% level. It is inferred that simple domestic heat treatment procedures such as pan roasting and microwave heating can effectively check the rancidity in rice bran for a considerable period of storage, making it suitable for possible animallhuman consumption. (c) 2006 Society of Chemical Industry.