Title
Measurement of the diffusion coefficient and hydrogen bonds of water in a dry-protective solution by microscopic near-infrared spectroscopy
Author
Lin Wei, Ryo Shirakashi
Year
2020
Journal
Food and Bioproducts Processing
Abstract
The water diffusion coefficients in highly concentrated ε-poly-l-lysine (PLL) and the disaccharides trehalose and sucrose were obtained by measuring the water distribution in sample solutions during the unsteady one-dimensional drying. The combination peak area of water in the near-infrared absorbance spectrum was measured to evaluate the water retained in the sample. The water diffusion coefficients were calculated by solving the differential equation of the diffusion coefficient that is derived from Fick’s law. Additionally, the measured combination peak areas of water allow for evaluating the hydrogen bond states of water molecules in sample solution. The evaluated hydrogen bond states of PLL and the disaccharide solutions showed drastic changes at approximately 50wt% water mass concentration, below which the water diffusion coefficients with respect to the water mass concentration are not identical. From these results, the conformation changes in PLL and the strong interactions of water and sample solutes are suggested.
Instrument
IRT-5200
Keywords
DiffusionNear-infrared, Drying process, Water bound state