Comparison of the molecular structure of heat and pressure-treated corn starch based on experimental data and molecular dynamics simulation
2022
Liu, Zhenyu | Fu, Yongxia | Zhang, Fan | Zhao, Qingyu | Xue, Yong | Hu, Jinrong | Shen, Qun
The effect of high hydrostatic pressure (HHP) and heating on the molecular structure of corn starch were firstly studied using classical experimental methods and molecular dynamics (MD) simulation. Heat-treated (HT) starches showed more amorphous content further than pressure-treated (PT) starches at similar DGs, further confirming that a higher level of gelatinization occurred after heating. Compared with PT starches, longer external B₂ and B₃ chains (DP > 25) degraded more into A chains (DP 6–12) in HT samples at a similar degree of gelatinization (DG). Heating increased the breakage of α-1,4-glycosidic bonds and significantly reduced molecular weights even one third of the native corn starch at 100% DG. On the other hand, MD results showed that HHP triggered a greater number of amylose-water inter-molecular hydrogen bonds which agreed well with the higher the freedom degree of water molecules in PT starches. Regarding to various energy changes, PT starches exhibited lower bonding-related energies, but higher Van der Waals and electrostatic forces than HT ones. This study adds to understanding of the different molecular features of heating and HHP gelatinization and provides a molecular tool to assist the starch industry in selecting better modification parameters.
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