A Novel Thermoreversible Gelling Product Made by Enzymatic Modification of Starch

摘要

Amylomaltases or D-enzyme (4-alpha-glucanotransferases; E.G. 2.4.1.25) are carbohydrate-active enzymes that catalyze the transfer of glucan units from one alpha-glucan to another in a disproportionation reaction. These enzymes are involved in starch metabolism in plants or maltose/glycogen metabolism in many microorganisms. The amylomaltase of the hyperthermophilic bacterium Thermus thermophilus HB8 was overproduced in Eschehchia coli, partially purified and used to modify potato starch. The action of amylomaltase caused the disappearance of amylose and the broadening of the side-chain length distribution in amylopectin, which resulted in a product with both shorter and longer side chains than in the parent starch. Amylomaltase-treated potato starchshowed thermoreversible gelation at concentrations of 3% (w/v) or more, thus making it comparable to gelatin. Because of its animal origin, gelatin is not accepted by several consumer groups. Therefore, the amylomaltase-treated potato starch might be agood plant-derived substitute for gelatin.