Determining the Mechanism and Parameters of Hydrate Formation and Loss in Glucose

作者：Scholl Sarah K; Schmidt Shelly J^*

来源：Journal of Food Science, 2014, 79(11): E2232-E2244.

DOI：10.1111/1750-3841.12671

• anhydrous glucose
• glucose monohydrate
• hydrate formation
• hydrate loss
• solid-state kinetics

Water-solid interactions are known to play a major role in the chemical and physical stability of food materials. Despite its extensive use throughout the food industry, the mechanism and parameters of hydrate formation and loss in glucose are not well characterized. Hydrate formation in alpha-anhydrous glucose (-AG) and hydrate loss in glucose monohydrate (GM) were studied under equilibrium conditions at various relative humidity (RH) values using saturated salt slurries for 1 y. The mechanism of hydrate formation and hydrate loss were determined through mathematical modeling of Dynamic Vapor Sorption data and Raman spectroscopy was used to confirm the mechanisms. The critical temperature for hydrate loss in GM was determined using thermogravimetric analysis (TGA). The moisture sorption profiles of -AG and GM were also studied under dynamic conditions using an AquaSorp Isotherm Generator. Hydrate formation was observed at and above 68% RH at 25 degrees C and the conversion of -AG to GM can best be described as following a nucleation mechanism, however, diffusion and/or geometric contraction mechanisms were also observed by Raman spectroscopy subsequent to the coalescence of initial nucleation sites. Hydrate loss was observed to occur at and below 11% RH at 25 degrees C during RH storage and at 70 degrees C during TGA. The conversion of GM to -AG follows nucleation and diffusion mechanisms. Hydrate formation was evident under dynamic conditions in -AG and GM prior to deliquescence. This research is the first to report hydrate formation and loss parameters for crystalline -AG and GM during extended storage at 25 degrees C.
Practical Application This study is the 1st to report the parameters of hydrate formation in anhydrous glucose (anhydrous dextrose) and hydrate loss in glucose monohydrate (dextrose) during 1 y of storage. This information is essential for further investigation of the physical stability of systems containing hydrate-forming materials. Understanding hydrate formation and loss is also critical to avoid product loss for many food ingredients such as: glucose, lactose, maltose, citric acid, and other food grade materials that form hydrates.

• 出版日期2014-11