The work dealt with the diffusional mobility of thiamin embedded in a high-solid matrix of κ-carrageenan with glucose syrup. It utilized thermomechanical analysis in the form of modulated differential scanning calorimetry and small-deformation dynamic oscillation in shear, Fourier transform infrared spectroscopy, wide angle X-ray diffraction, scanning electron microscopy and UV-vis spectrophotometry. The structural properties of the matrix were assessed in a temperature induced rubber-to-glass transformation. A thiamin-dye binding assay was employed to monitor the diffusion process of the vitamin from the high-solid preparation to ethylene glycol. The relationship between mechanical properties of the carbohydrate matrix and vitamin mobility was assessed via the application of the combined framework of the free volume theory and the predictions of the reaction rate theory. Results argue that the transport of the micronutrient is governed by the structural relaxation of the high-solid matrix. These were further treated with the concept of Fickian diffusion coefficient to provide the rate of the bioactive compound mobility within the present experimental settings.
Keywords: Diffusion kinetics; Glass transition temperature; Glucose syrup; Thiamin; κ-Carrageenan.
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