Preparation of high-quality resistant dextrin through pyrodextrin by a multienzyme complex

As a soluble food raw material with a low calorie content,resistant dextrin (RD) has broad application prospects in the food industry.Branching enzymes (BEs),as a key enzyme for RD preparation,can break the α-1,4 glycosidic bonds of donor chains and reconstruct the cleaved chains to acceptor chains through the α-1,6 glycosidic bonds.BEs with high transglucosidic activity toward amylopectin and short-chain substrates are urgently needed to increase the quality of RD.Herein,BE derived from Thermuobifida fusca (TfBE) was mined and characterized.The optimal temperature and pH of the TfBE were 40 ℃ and 6.5,respectively.A total of 1500 U/g substrate TfBE reacted with 20% (w/v) pyrodextrin for 12 h,the ratio of α-1,4 to α-1,6 glycosidic bonds was changed from 3.52:1 to 2.33:1,and the content of enzyme-resistant components notably increased from 44.0% to 53.8%.Furthermore,to make full use of receptor chains and small molecular sugars in the reaction system,a multienzyme complex of TfBE with T.fusca α-cyclodextrin glucosyltransferase (TfCGTase),TfBE with TfCGTase and Aspergillus nidulans α-glucosidase (AnGS) was used to further increase the enzyme resistance of RD from 44.0% to 65.3% and 70.6%,respectively.The developed multienzyme complex method could effectively contribute to improving the production quality and efficiency of RD preparation.