Extraction of total dietary fiber from rice bran by using enzymatic system

Abstract

Protease and alpha-amylase activities play important roles in determining total dietary fiber (TDF) percentage. Five different types of rice bran was analyzed in TDF by enzymatic- gravimetric methods in order to investigate the highest dietary fiber content for applying in food industry. Among the types, the TDF ranges from 20.93 ± 1.59 to 26.56 ± 2.39% with the most was the Commercial Rice Bran (CRB). Both of them were analyzed on the CRB. Eight of protease and six of alpha-amylase activities were observed in this report. For protease, using the Kjeldahl method with Nitrogen factor was 6.25 and the optimum was 1500U/assay with 7.48 ± 0.30% compared with the total protein 12.63 ± 0.10% (hydrolyzed protein concentration was 5.15%). For alpha-amylase, the TDF content ranges from 26.63 ± 2.78% to 35.19 ± 2.90% correlated to the activities decreasing from 1280 : 960 : 640 : 320 : 160 : 80 and the optimum was 640U/assay with TDF content 26.56 ± 2.39%. Moisture and ash content was measured for each types and each assay for calculating the final TDF content.

Keywords: Dietary fiber, rice bran, alpha-amylase, protease K, amyloglucosidase, enzymatic-gravimetric method, Kjeldahl method.