2.4. Susceptibility of glutinous rice starch to digestive enzymes
2.4.1. Enzyme kinetics of ˛-amylase on native and gelatinized
starches
The native or gelatinized glutinous rice starch (0–25 mg/mL) and
porcine pancreatic -amylase (10 U/mL) were mixed in a phosphate
buffered saline (PBS) with a pH of 6.8 and incubated in a
water bath controlled at 37 ◦C. After 60 min, the slurry was placed
in ice water immediately for 10 min to inactivate -amylase. The
amount of reducing sugar was determined by using DNS colorimetric
assay (Dubois et al., 1956). The Michaelis–Menten kinetics
describes the action of many reactions where the enzyme concentration
is small relative to the substrate concentration. The
Michaelis–Menten equation (Eq. (2)) is as follows (Dona et al.,
2010):