The Multiscale Structural Properties and In-Vitro Digestibility of High Amylose Corn Starch During Autoclaving-Cooling Treatment

This work investigates the relationship between multiscale structural properties in high amylose corn starch (HACS) and its in-vitro digestibility by analyzing the effects of autoclaving-cooling treatment (ACT). Differential scanning calorimetry (DSC) shows that HACS displays a higher gelatinization temperature, wider endothermic gelatinization range, and higher enthalpy. Autoclaved corn starch exhibits enhanced thermal stability than the raw corn starch. X-ray diffraction (XRD) shows that ACT does not change the crystalline type but increases the relative crystallinity (RC). Fourier transform infrared spectroscopy (FTIR) indicates that HACS exhibits a higher degree of order (DO) and double helixes (DHs) than normal corn starch (NCS), which are reduced by ACT. Scanning electron microscopy (SEM) reveals that HACS displays denser structures and smaller particle morphologies than NCS. After ACT, the granular of autoclaved corn starch shows a rough fiber network structure. Digestibility analysis reveals a positive correlation between the amylose content and resistant starch (RS) level in raw starch, while ACT promotes significant RS formation. This suggests that amylose promotes ordered structure formation, while autoclaving increased digestive resistance. A positive correlation is evident between the amylose and resistant starch (RS) content in the raw starch. Autoclaving-cooling treatment (ACT) significantly increases the RS content of the starch while decreasing the rapid (RDS) and slow digestible starch (SDS) levels. Starch with B + V-type crystals is more resistant to digestion than A-type crystals. The dense structure and smooth surface enhance the digestive resistance of the high amylose corn starch (HACS) granules. image