Study on alpha-amylase hydrolysis of potato amylopectin by a quartz crystal microbalance.

Potato amylopectin with phosphate groups was immobilized on a quartz crystal microbalance with dissipation monitoring (QCMD) using the attractive interaction between opposite charges, and enzymatic starch hydrolysis was monitored directly. Poly( L-lysine) (PLL) proved to be an appropriate cationic linker between the QCMD silica sensor and potato amylopectin. Increased mass and dissipation were observed when amylopectin was adsorbed onto the PLL layer and reversed when alpha-amylase was added. The effect of chitosan with cationic property on the hydrolysis of amylopectin was studied. Chitosan was observed to be adsorbed onto the amylopectin surface and to suppress hydrolysis by alpha-amylase. The formation of alternating layers of amylopectin and chitosan was monitored by QCMD. Amylopectin-chitosan trilayers increased resistance to digestion by alpha-amylase compared to one layer and to control without chitosan.