The physicochemical properties of rice bran extracts with ultrasonic treatment

MC Yuan1, TL Jeng2, MI Kuo1

1 Department of Food Science, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei City 24205, Taiwan
2Biotechnology and Plant Germplasm Division, Taiwan Agricultural Research Institute Council of Agriculture, Executive Yuan, Division, Taichung City, Taiwan
Rice bran is a by-product of rice milling. It is rich in nutrients and provides hypoallergenic and anti-cancer ability. Application of ultrasound in rice bran extraction is considered safe, non-toxic, and environmentally friendly. The objective of this study was to investigate the effect of ultrasonic treatment on the physicochemical properties of rice bran extracts. Rice bran was thermal-stabilized with water (1:10 w/v) at 80oC for 20 min. The slurry was treated with either ultrasound bath or probe for different time and then centrifuged. The supernatant was freeze-dried to obtain the rice bran extract 1 (RBE1). The rice bran extract 2 (RBE2) was prepared by precipitation the supernatant using pH adjustment to pH4 and then freeze-dried. Results showed that the yield of RBE1 was more than RBE2. Both RBE1 and RBE2 extracted with ultrasound probe exhibited greater yield than ultrasound bath. The RBE1 extracted with ultrasound probe for 10 min had the higher yield. The protein and fat contents of RBE2 were higher than RBE1. The RBE1 treated with ultrasound probe had the highest carbohydrate content and the lowest was RBE2 treated with ultrasound probe. The color of RBE1 and RBE2 were significantly different. The RBE2 was darker and more red and yellow then RBE1. Use the ultrasound probe treatment could improve the yield and increase the protein content of RBE1 and RBE2. On the other hand, it was also able reduce the fat content of extracts. Threrfore, the ultrasound probe treatment in rice bran extraction is good for food industry application.
Keywords: rice bran, ultrasound, physicochemical properties
References:
1	Chittapalo T and Moomhorm A. (2009). Ultrasonic assisted alkali extraction of protein from defatted rice bran and properties of the protein concentrates. Int J Food Sci Tech, 44, 1843-1849.
2	Xia N, Wang J, Yang X, Yin S, Qi J, Hu L, Zhou X. (2012). Preparation and characterization of protein from heat-stabilized rice bran using hydrothermal cooking combined with amylase pretreatment. J Food Eng, 110, 95-101.