College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, P. R. China.
Fujian Provincial Key Laboratory of Quality Science and Processing Technology in Special Starch, Fujian Agriculture and Forestry University, Fuzhou, 350002, P. R. China.
J Food Sci. 2020 Dec;85(12):4241-4248. doi: 10.1111/1750-3841.15492. Epub 2020 Nov 20.
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.
微波真空干燥（MVD）被应用于脱水莲子（Nelumbo nucifera Gaertn.）。本文评估了 MVD 后莲子分子、晶体和形态结构特性的变化。结果表明，随着微波功率密度的增加，δ(CH)弯曲、β(CH)、ν(OH)和碳氧双键 (C=O) 的频率增加。此外，随着微波功率密度的增加，结晶度的转变焓逐渐增加，这与形成结晶淀粉、再结晶以及淀粉-脂质结构的复合物有关，这取决于形成的氢键。MVD 过程导致莲子的分子极性发生变化，介电性能也发生了变化。介电性能与分子和晶体结构的变化相互作用。随着微波功率密度的增加，由于淀粉颗粒的形状被破坏，并且由于非淀粉成分的存在，颗粒变得聚集在一起，因此莲子粉的形态发生了变化。所有这些结果都解释了 MVD 干燥过程中莲子中聚合物分子之间的相互作用。
