การคงสภาพและปรับปรุงลักษณะทางกายภาพของรำข้าว เพื่อใช้เป็นผลิตภัณฑ์มูลค่าสูง

Abstract

The objectives of this research were to study the lipase inhibition in two varieties of rice bran (a nomal rice; RD 6 and a black rice; Kum Doi Saket) using protease enzymes, and to develop the high anthocyanin beverage using the stabilized black rice bran as an ingradient. Five protease enzymes (bromelain, papain, trypsin, chymotrypsin and Flavourzyme®) were compared for their inhibition efficiency at 2 concentations (4.0 and 8.0 mg/ml). Degree of hydrolysis, protein solubility and lipase activity were monitored every 15 min of hydrolysis time (120 min). The results showed that the hydrolysis rate of protease enzymes at 8.0 mg/ml concentration was higher than of 4.0 mg/ml concentration. Among 5 protease enzymes, trypsin, chymotrypsin and papain showed a higher rate of hydrolysis and protein solubility than those of bromelain and Flavourzyme®. Besides, trypsin, chymotrypsin and papain also showed the high of lipase inactivation. For the economic reason, papain at 4.0 mg/ml was selected to produce the enzymatic stabilized rice bran (ESB). ESB contained the higher concentration of γ-oryzanol, vitamin E and total phenolic than raw rice bran (RB) and thermal stabilized rice bran (TSB). ESB, RB and TSB were stored at ambient temperature for 2 months. The lipase activity of ESB and TSB were not changed throughout the storage period. After storage, the amount of the free fatty acid in RB, TSB and ESB were 43.38, 13.27 and 12.29%, respectively. Anthocyanins extract from black ESB was used as an ingradient to develop the high anthocyanin beverage. The results from customer servey conclude that strawberry flavor was the most flavorable flavor. To improve anthocyanin stability, this beverage was added with differenct co-pigments (green tea extract, gallic acid and ascorbic acid). It was found that green tea extract was the best co-pigment which can reduce the lost of anthocyanins from the heat of pasturization (85 oC for 15 min). However, green tea extract didn’t prevent the degradation of anthocyanin in beverage stored under fluorescent light. Key words: Rice bran, Lipase, Protease enzymes, Co-pigments