Determination of amylose, amylopectin, and total starch content

Amylose content (%) was determined by iodine colorimetry. The method is as follows: Weigh about 10 g grains and grind them into powder, and then pass the powder through an 80 mesh sieve. Then weigh 50 ± 0.2 mg of the sieved sample, put it into a 50 ml volumetric flask, add 0.5 ml of 95% ethanol solution, and then add 4.5 ml of sodium hydroxide solution, and incubate overnight. Add constant volume to 50 ml to prepare liquid. Take 0.5 ml the liquid into 10 ml centrifuge tube, add 5 ml water and 0.1 ml acetic acid solution, shake well, add 0.2 ml iodine reagent, fix the volume to 10 ml, shake well, and stand for 10 min. The absorbance was measured at 620 nm with a spectrophotometer. The absorbance value was compared with the standard curve to obtain the corresponding amylose content. Amylopectin content (%) was determined by amylopectin content kit (Suzhou Keming Biotechnology Co., Ltd., Suzhou, Jiangsu, China).

Total starch content (%) = amylose content (%) + amylopectin content (%).