Effect of Drying Method on Physicochemical and Functional Properties of Rice Bran Insoluble Dietary Fiber

• 1、National Engineering Laboratory for Cereal Fermentation Technology， Jiangnan University， Wuxi Jiangsu

Abstract：Insoluble dietary fiber from rice bran extracted by enzymatic-chemical method was taken as the research object. It was dried by spray drying, hot air drying and vacuum freeze drying. The physicochemical properties of each samples, the ability to bind Cd2+ and glucose were compared and analyzed. The results showed that the macroscopic morphology of rice bran insoluble dietary fiber was significantly different after drying in different ways. The hot air drying samples had a darker color, the color of vacuum freeze drying samples were close to the original color of rice bran, and samples were fluffy and no agglomeration; There were significant differences in physicochemical indexes (P<0.05). Among them, rice bran insoluble dietary fiber obtained by vacuum freeze drying were superior. Among them, rice bran insoluble dietary fiber obtained by vacuum freeze drying were superior, water holding capacity is 1.83 g/g higher than spray drying, and 1.23 g/g (45°C) higher than hot air drying and 1.84 g/g (101°C), the oil holding capacity (4.21 g/g) and expansion force (4.99 mL/g) were also higher than other dry samples. However, there was no significant difference in cation exchange capacity, both close to 0.16 mmol/g. Fourier transform infrared spectroscopy showed that only the absorption intensity changed at the corresponding wavelength after drying, and the functional group composition of the sample did not change significantly; X-ray diffraction analysis showed that the crystallinity of the vacuum freeze-dried sample was the smallest (30.19%). In addition, the vacuum freeze drying samples had better binding capacity for Cd2+ and glucose than other two samples: the maximum binding capacity were 1.19 and 1.08 times of spray drying, 1.28 and 1.71 times (45°C) of hot air drying, and 1.33 and 3.1 times (101°C) respectively. Comprehensive comparison, vacuum freeze drying is more suitable for rice bran insoluble dietary fiber than spray drying and hot air drying.

Keywords： rice bran insoluble dietary fiber drying physicochemical properties Cd2+ glucose