The FT-IR spectra of starch samples in KBr discs (2 mg starch/150 mg KBr disc) were recorded using a Nicolet IR200 spectrophotometer with a resolution of 4 cm−1 in a spectral range of 4000–400 cm−1. Omnic 8.0 software (Thermo Fisher Scientific Inc., WI, USA) was used for baseline-correction of the FT-IR spectra of starch samples, and Origin 8.0 (OriginLab Corp., MA, USA) was used for fitting the experimental curve. All analyses were performed in triplicate.