| Abstract | This research aimed to investigate the optimization of extraction and purification of -oryzanol in which rice bran oil soapstock (RBOS) is a product from the chemical refining process of rice bran oil production. The RBOS was dry and contained 9.91% of -oryzanol. RBOS was extracted from the -oryzanol through soxhlet extraction, ultrasonic assisted extraction, and the integration between the untrasonic assisted method and soxhletex method. Moreover, the RBOS was investigated for optimization by Response Surface Methodology (RSM) and through the Box-Benhken Experimental Design (BBD).
The results indicated that optimization of the soxhlet extraction was identified as 1:2 solid to solvent ration, 70.1 ºC extraction temperature and 7.26 h extraction for extracted -oryzanol yield of 8.74% dry basis. For ultrasonic-assisted extraction, the process variables were ultrasonic frequency, extraction temperature and extraction period. The optimal ultrasonic assisted extraction conditions were identified as 12 kHz ultrasonic frequency, 74.1 ºC extraction temperature and 60 min extraction for maximum -oryzanol yield of 5.15% dry basis. Furthermore, the optimal conditions of both soxhlet extraction and ultrasonic assisted were chosen to extract -oryzanol which gave the highest -oryzanol yield of 9.05% dry basis. However, purification of -oryzanol was low. So, the purification of -oryzanol was achieved by a two-step crystallization process to recover -oryzanol from enriched extracts. Optimal conditions of a two-step crystallization process were found that the -oryzanol was dissolved in the 3:7 of ethyl acetate: methanol ratio at -22 ºC for 24 h for the first crystallization step. Then in the second crystallization step, the supernatant obtained through the first step was kept at 5 ºC for 48 h. Under optimal conditions of a two-step crystallization, purity and recovery of -oryzanol from all extraction methods were 87%. However, -oryzanol utilization was limited because of -oryzanol’s dissolving qualities. Then, the extracted -oryzanol was investigated through oil-in-water emulsion 80:20 (aqueous phase 80%wt and rice bran oil 20%wt). Rice bran oil consisted of 2%wt -oryzanol and aquepus phase consisted of 1.0%wt Whey Protein Concentrate and 10%wt Maltodextrin (DE10). The extracted -oryzanol (Encapsulated -oryzanol extract power: EOEP) was produced by spray drying. The results indicated that the EOEP were a smooth spheroid powder, had low moisture content that was lower than 3%, the encapsulated efficiency and yields were more than 95%, and the dissolving quality was high than 75%. For the maintenance, the encapsulated extract -oryzanol powder could be kept for 277 days at 25 ºC and 613 days at 4 ºC. Moreover, the -oryzanol powder used in salad dressings was also studied. The results indicated that the encapsulated -oryzanol extract power can be used as a food ingredient in salad dressings, which had a good effect on -oryzanol content and antioxidant activity.
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