Production and characterization of digestion-resistant starch by the reaction of Neisseria polysaccharea amylosucrase

Recombinant amylosucrase (200 U/mL) from Neisseria polysaccharea was used to produce digestion-resistant starch (RS) using 1-3% (w/v) corn starches and 0.1-0.5 M sucrose incubated at 35 degrees C for 24 h. Characterization of the obtained enzyme-modified starches was investigated. Results show that the yields of the enzyme-modified starches were inversely proportional to the original amylose contents of corn starches. After enzymatic reaction, insoluble AS contents increased by 22.3 and 20.7% from 6.9% of waxy and 7.7% of normal corn starches, respectively, using 3.0% starch as acceptor and 0.3 M sucrose as donor, while amylomaize VII showed the lowest increase (8.5%) in RS content. The crystalline polymorph of these enzyme-modified starches resulted in the B-type immediately after enzymatic reaction. The enzyme-modified starches displayed higher melting peak temperatures (85.6-100.6 degrees C) compared to their native starch counterparts (70.1-78.4 degrees C). After enzymatic reaction, pasting temperature increased in waxy (71.9 -> 77.6 degrees C) and normal corn starches (75.3 -> 80.6 degrees C), and the peak viscosity of waxy corn starches increased from 264 to 349 RVU, whereas that of normal corn starches decreased from 235 to 66 RVU.