“…It is well known that FT‐IR spectroscopy can measure the structure of polysaccharides, such as the monosaccharide types, glycosidic bonds, and functional groups (Yang & Zhang, 2009). At the same time, FT‐IR can also be used to evaluate the molecular vibrations and the polar bonds between different atoms (Wu et al., 2015). The results of the characteristic absorptions of AAP, such as peaks at 3,390.87, 2,924.17, 1,619.11, 1,423.65, and 1,071.95 cm −1 (Chai & Zhao, 2016; Liu et al., 2016), are shown in Figure 5.…”