Release Mechanism of Essential Fatty Acids in Polysaccharide Matrices Undergoing Glass Transition

Identification of theoretical mechanisms governing molecular diffusion of essential fatty acids (oleic and α-linolenic acid) in high solid matrices was carried out on two polysaccharide matrices of high-methoxy pectin and κ-carrageenan in the presence of co-solute glucose syrup and polydextrose, respectively. Physicochemical analysis of this system utilised modulated DSC, dynamic oscillation in shear, ESEM, FTIR and WAX diffraction. The carbohydrate matrices were conditioned through an extensive temperature range to induce changes in molecular morphology and identify the network glass transition temperature. Thermally induced variation in phase morphology was employed to rationalise transportation patterns of the bioactive compound within the high-solid preparation. Thus, experimental observations using UV-vis spectroscopy modelled diffusion kinetics to document the mobility arresting effect of the vitrifying matrix on the micro-constituent. Within the glass transition region, results argue that free volume theory is the molecular process governing structural relaxation. Further, Less Fickian diffusion follows well the rate of molecular transport of the fatty acids as a function of time and temperature of observation in the condensed matrices.