Optimized extraction of soluble defatted rice bran fiber and its application for microencapsulation of fish oil
Master of Science (MS)
School of Nutrition and Food Sciences
Defatted rice bran (DRB) is a byproduct of rice milling and rice bran oil extraction. Soluble rice bran fiber (SRBF) extracted from defatted rice bran is known for its antioxidant activity and hypocholesterolemic effects in human, while purified menhaden oil (PMO) is a good source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The goal of the study was to estimate optimum extraction conditions to extract SRBF from DRB, develop a cost effective method to purify SRBF and produce microencapsulated PMO with SRBF. The response surface methodology showed that an estimated optimum yield of SRBF (7.89%) could be extracted from DRB with 3% Ca(OH)2 solution to DRB ratio 29.75:1 and stirred for 1 hr at 84oC and also Ca(OH)2 solution concentration was the most effective factor among the conditions used to extract SRBF. Our study showed that conventional processing steps, such as dialysis and alcohol precipitation, for removing mineral and monosaccharides and other small molecules from SRBF, could be replaced with the ultrafiltration technology. The ultrafiltration for purifying SRBF solution at 100 kPa with 10 kDa MWCO membrane required less time than filtering the solution at the same pressure with 1 and 5 kDa MWCO membranes. The estimated microencapsulated PMO with SRBF powder (MFMO) production rate using spray dryer was 3.45 * 10-5 kg dry solids/s and was higher than the actual production rate 2.31 * 10-5 kg dry solids/s. The energy required to increase the inlet ambient air temperature from 27.1 to 180 oC and evaporation rate for spray drying the emulsion was 2.78 kJ/s and 7.8 * 10-3 kg water/s, respectively. EPA and DHA contents of MFMO were 11.52% and 4.51%, respectively. The particle size of 90% MFMO ranged from 8 to 62 um, and the volume-length diameter of MFMO was 28.5 um. The study demonstrated that optimum extraction conditions for extracting SRBF from DRB could be achieved through the response surface methodology, conventional purification steps of SRBF including dialysis and alcohol precipitation could be replaced with ultrafiltration technology, and the MFMO could be provided with potential health benefits for humans.
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Wan, Yuting, "Optimized extraction of soluble defatted rice bran fiber and its application for microencapsulation of fish oil" (2010). LSU Master's Theses. 1377.