Aqueous enzymatic extraction of oil from rice bran and its quality
evaluation.
Abstract
Rice bran as a by-product of rice processing can be used to produce oil.
The main objective of this study was to select appropriate enzymes for
aqueous enzymatic extraction (AEE) and evaluated the quality of rice
bran oil (RBO) obtained by AEE and solvent extraction (SE). In addition,
the microstructure of rice bran before and after different extraction
processes were also observed. The results showed that Alcalase 2.4L was
the most effective in releasing RBO. Moreover, iodine value and
saponification value in the AEE-extracted oil (AEEO) were found to be
higher than the SE-extracted oil (SEO). AEEO with lower acid value and
peroxide value was considered to be a high quality and the content of
wax and phospholipid in AEEO were lower, which could simplify the
refining steps. Additionally, AEEO exhibited a higher content of
unsaturated fatty acids (76.31%), vitamin E (1004.42 mg/kg), sterols
(7749.44 mg/100 g), squalene (2962.56 mg/kg) and oryzanol (2.43%). In
comparison to the SEO, AEEO was found to have lower crystallization and
melting points. Scanning electron microscope (SEM) results showed the
destruction of cell walls and the decrease of substances in the cell by
AEE. In general, the results of this study showed improvement in the
quality of the AEEO and provided necessary data support for green
extraction of RBO in food industry.