부산대학교 도서관

With the objective of characterizing water sorption kinetics of glutinous rice flour during extended water vapor exposure, water adsorption and desorption measurements were conducted at nine relative humidity (RH) levels for up to 1,500 min per step, and displayed in a logarithmic time scale. A three‐stage sorption kinetics was observed, and the final stage was characterized with a very long and slow process. The final sections of the kinetic curves were concave to log(t) axis for adsorption while linear for desorption, even after the flour was gelatinized. Increment in RH step and flour particle size, and variation in water content can only postpone starting of the linear stage. Analysis using an Elovich‐type model indicated that both adsorption and desorption can be treated as processes whose activation energy varied consistently during sorption. Reaction order difference between adsorption and desorption was the major contributor to their distinct kinetic responses in the final stages. Practical Applications: Water sorption kinetic measurements are necessary for exploring mass transfer mechanism, and determining parameters such as water diffusivity and interfacial mass transfer coefficient. Extended measurement duration allows one to catch the entire characteristics of a kinetic process. Distinct kinetic features between adsorption and desorption of glutinous rice flour were observed when the data were plotted against logarithm of time. The later stage was a slow process. Further analysis using an Elovich‐type model indicated that both adsorption and desorption were processes with varying activation energy. This information can be potentially helpful in optimizing both the quality of food product and the economics of many food processes involving water transfer. [ABSTRACT FROM AUTHOR]