Figure 4 C displays the FTIR spectra of noodles cooked by different methods 800~1200 cm-1 represents the fingerprint region of starch van Soest et al 1995 As shown in Figure 4 C noodles treated with h

Figure 4 C displayed the FTIR spectra of noodles cooked by different methods, where the fingerprint region of starch (800~1200 cm-1) was represented (van Soest et al., 1995). As shown in Figure 4 C, noodles treated with heat exhibited similar spectra to those without treatment, indicating that no new intermolecular covalent bonds were formed (no new characteristic peaks had appeared). A study conducted by Lu et al. (Lu et al., 2016) had demonstrated that hydrogen bonding was the primary interaction force between starch and protein in the composite system. In comparison to untreated samples, the O-H characteristic absorption peak of noodles after heat treatment had shifted significantly to a higher frequency, indicating a weakening of hydrogen bonding in noodle systems. As depicted in Figure 5, the peak intensity ratio of the mature noodle system had been significantly influenced by heat treatment. Compared to untreated noodles, the order of peak intensity ratio at 1047/1022 cm-1 had been found to be: roasted > fried > steamed > boiled. The order of peak intensity ratio at 1022/995 cm-1 had been found to be: fried < roasted < boiled < steamed. These findings had suggested that the heat treatment had weakened the short-range ordered structure and intra-molecular hydrogen bond strength of starch, which in turn had accelerated the enzymatic reaction to some extent. The FTIR results had been consistent with previous studies, which had proposed a positive correlation between RS and 1047/1022 cm-1, indicating that the short-range ordered structure of starch may have directly impacted digestion (Shumoy et al., 2018).