Rice bran oil extraction in Sri Lanka: Data for process equipment design

Abstract

Rice bran oil is widely used in pharmaceutical, food and chemical industries due to its unique properties and high medicinal value. In this study, extraction of rice bran oil from various brands of rice bran available in Sri Lanka has been studied and data necessary for extraction, equipment design and process predictions have been determined. Experiments were conducted using a Soxhlet apparatus and a pilot-scale leaching unit, to extract rice bran oil using hexane as the solvent. The key factors controlling the extraction and optimal operating conditions were identified. Analysis of free fatty acid content in the extracted oil showed that steaming is the most effective method of bran pre-treatment. Bran obtained from parboiled paddy has a higher yield of rice bran oil compared with the raw rice bran, despite the oils darker colour. Linoleic, oleic and palmitic acids are the major fatty acid constituents in rice bran oil. Equilibrium data show no preferential adsorption of oil or solvent to the inert bran and approximately constant solid/solution ratios in the underflow raffinate streams. Batch extraction tests showed the rate of extraction decreases with time and the solution approaches saturation at an exponential rate. Mass transfer coefficient was obtained for the system.