Dynamics of Water Molecules in Sago Starch Determined by ¹H NMR

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 To study the behavior of water molecules in the sago (Metroxylon sagu) starch (C_A type starch) structure, a ¹H solid state cross polarization (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) technique has been applied using corn (type A starch) and potato (type B starch) as references. The exchange of H₂O molecules on/in the sago starch structure to D₂O based on the H-D isotopic exchange was analyzed with time from 1 to 24 hrs. The amount of water-molecule exchange on/in sago starch increased with the increasing contact time with D₂O, which was similar to the exchange amount of water-molecule of corn starch and smaller than that of potato starch. This suggested that the type B starch holds a larger channel space of a hexagonal crystalline structure for water molecules than does the type A starch and that the type C_A starch showed the dynamics of water molecules, similarly to type A.