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Effect of different enzymatic extractions on molecular weight distribution, rheological and microstructural properties of barley bran β-glucan

Karimi, Reza, Azizi, Mohammad Hossein, Xu, Qin
International journal of biological macromolecules 2019 v.126 pp. 298-309
alpha-amylase, barley bran, beta-glucans, glucan 1,4-alpha-glucosidase, molecular weight, pentosans, proteinases, pullulanase, rheological properties, starch, xylanases
The aim of this study was to investigate the effects of different enzymatic extraction procedures on molecular weight distribution, rheological behavior, microstructural properties, compositional factors including ash (%), starch (%), pentosans (%), β-glucan (%) and extraction yield (%) of the fiber samples obtained from barley bran. Different enzymes including α-amylase, protease, glucoamylase, pullulanase and two types of xylanase were used in special combinations to extract β-glucan from barley bran. The three-step purification procedures with α-amylase, protease and xylanase have been proved to be efficient in increasing the β-glucan content and in removing starch, protein and pentosans from the barley bran in 4 h. The procedures also have resulted in highest β-glucan purity and lowest molecular weight of ~89% and 2 × 104 g·mol−1, respectively. While the respective lowest β-glucan purity and highest molecular weight of ~55% and 16 × 104 g·mol−1 were obtained by only α-amylase treatment in 1.5 h. Regardless of different purity, extraction yield and composition, the results of this study showed that how enzymatic extractions affect molecular-rheological relationship of the β-glucan-enriched fibers, which may help to understand their function in the digestive track and industrial processes.