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Polysaccharide Modification through Green Technology: Role of Endodextranase in Improving the Physicochemical Properties of (1→3)(1→6)-α‑d‑Glucan

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journal contribution
posted on 22.07.2015, 00:00 by Chao Huang, Ming Miao, Srinivas Janaswamy, Bruce R. Hamaker, Xingfeng Li, Bo Jiang
The structure and properties of bioengineered (1→3)(1→6)-α-d-glucan subjected to endodextranase treatment were investigated. Upon enzyme treatment, OD220 and Mw decreased substantially during the first 60 min and thereafter slowed as the modification progressed. Compared to the native glucan, the modified sample solution had a lighter opalescent, bluish-white color. The morphological analysis revealed that bioengineered glucan produced quite a few small particles after hydrolysis. The molecular weight distribution curve gradually shifted to the low Mw region with a significant broadening distribution, and the chain hydrolysis reaction followed a combination of zeroth- and first-order processes. The NMR results showed some specific α-1,6 linkages of glucan chains were cleaved with enzyme treatment. The viscosity of modified glucan solution was markedly reduced, and the Newtonian plateaus were also observed at high shear rates (10–100 1/s). The above results suggested that the modified (1→3)(1→6)-α-d-glucan showed a tailor-made solution character similar to that of arabic gum and would be used as a novel food gum substitute in the design of artificial carbohydrate-based foods.