Release mechanism of omega-3 fatty acid in k-carrageenan/polydextrose system undergoing glass transition
VD Paramita, A Bannikova, and S Kasapis
School of Applied Sciences, RMIT University, Melbourne, Victoria 3000, Australia

Aiming to increase the bioavailability of omega-3 fatty acids, most of the studies so far have been carried out utilising the encapsulation techniques. However, there has been limited information available on exploration of the effectiveness of high solid matrices to curb the release of this bioactive ingredient. Therefore, this existing work was focused on the investigation of potential application of the high solid preparation containing k-carrageenan and polydextrose to entrap the linolenic fatty acid for further application as alternative protective materials in food and nutraceuticals. Physiochemical analysis of this high solid preparations utilised differential scanning calorimetry, ESEM, FTIR and WAX diffraction in combination with the small deformation oscillatory measurements in shear. Results revealed that the carbohydrate matrix undergoes vitrification with the mechanical Tg values being at -8 oC which have been also confirmed theoretically using the Williams, Landel and Ferry (WLF) and modified Arrhenius equations. Experimental observations on diffusion of bioactive compound using UV-vis spectroscopy suggested a limited release of fatty acid at temperatures below the recorded mechanical Tg. The introduced mathematical approach was combined with the spectroscopic shift factor affirmed the capacity of the biopolymers network to control release fatty acid at the vicinity of glass transition phenomena. Further, the Fickian diffusion modelling was brought in to quantify the rate of transport of bioactive compound as a function of time and temperature within the glass transition region. The diffusion coefficient of omega-3 fatty acid was compared with the fractional free volume of the high solid matrix to predict the relative mobility of this bioactive compound in this designed carbohydrate system.