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Functional group changes and chemical bond‐dependent dielectric properties of lotus seed flour with microwave vacuum drying
Author(s) -
Wang Weiwei,
Zheng Baodong,
Tian Yuting
Publication year - 2020
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/1750-3841.15492
Subject(s) - crystallinity , lotus , starch , crystallization , microwave , dielectric , molecule , chemistry , materials science , chemical engineering , botany , organic chemistry , crystallography , physics , optoelectronics , quantum mechanics , engineering , biology
Microwave vacuum drying (MVD) was applied to dehydrate lotus ( Nelumbo nucifera Gaertn.) seeds. This paper evaluated the changes of molecular, crystalline, and morphological structural properties of lotus seeds after MVD. The results showed the frequency of δ(CH) bending, β(CH), ν(OH), and carbon–oxygen double bonds (C = O) increased with increasing microwave power density. Moreover, as microwave power density increased, the transition enthalpy of crystallinity gradually increased, which was related to the formation of crystalline starch, re‐crystallization, and complexes of starch–lipid structure depending on the hydrogen bonds formed. The MVD process resulted molecular polarity of lotus seeds, whereas the dielectric properties also changed. The dielectric properties interacted with the changes of molecules and crystalline structure. The morphology of lotus seed flour changed because the shape of starch granules was disrupted and the granules became aggregated with nonstarch components as the microwave power density increased. All these results explain the interactions among polymer molecules in lotus seeds dried by MVD.