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 alpha-1,4 glycosidic bonds of donor chains and reconstruct the cleaved chains to acceptor chains through the alpha-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 degrees C and 6.5, respectively. A total of 1500 U/g substrate TfBE reacted with 20% (w/v) pyrodextrin for 12 h, the ratio of alpha-1,4 to alpha-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 alpha-cyclodextrin glucosyltransferase (TfCGTase), TfBE with TfCGTase and Aspergillus nidulans alpha-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.