Preparation and gel properties of low molecular weight curdlan by hydrolysis of curdlan with commercial α-amylase.

Low molecular weight curdlan (LMWC) was prepared by hydrolysis of curdlan with commercial α-amylase. The hydrolysis reaction was conducted using 31.94 mg α-amylase per 500 mL reaction mixture, which contained 5 g curdlan. The hydrolysis was performed at pH 5.98 and 55.92 °C for 10 min. The molecular weight and structure of LMWC were characterized by high-performance liquid chromatography and Fourier transform infrared spectroscopy, respectively. Generally, LMWC showed lower gel strength than high molecular weight curdlan (HMWC). Unlike HMWC, LMWC could form into a gel at 50 °C. By contrast, HMWC could form into a gel at pH 11, but LMWC gel failed to form at this pH level. The strength of LMWC and HMWC gels increased with increasing temperature and decreased with increasing pH level.