Mathematical modeling of the adsorption/desorption characteristics of anthocyanins from muscadine (Vitis rotundifolia cv. Noble) juice pomace on Amberlite FPX66 resin in a fixed bed column.

Background: Muscadine grape pomace, a by-product of juicing and wine-making, contains significant amounts of anthocyanin 3,5-diglucosides, known to be beneficial to human health.

Results: The objective of this research was to use mathematical modeling to investigate the adsorption/desorption characteristics of these anthocyanins from muscadine grape pomace on Amberlite FPX66 resin in a fixed bed column. Anthocyanins were extracted using hot water and ultrasound, and the extracts were loaded onto a resin column at five bed depths (5, 6, 8, 10 and 12 cm) using three flow rates (4, 6 and 8 mL min ). It was found that adsorption on the column fitted the bed depth service time (BDST) model and the empty bed residence time (EBRT) model. Desorption was achieved by eluting the column using ethanol at four concentrations (25, 40, 55 and 70% v/v) and could be described with an empirical sigmoid model. The breakthrough curves of anthocyanins fitted the BDST model for all three flow rates with R values of 0.983, 0.992 and 0.984 respectively. The EBRT model was successfully employed to find the operating lines, which allow for column scale-up while still achieving similar results to those found in a laboratory operation. Desorption with 40% (v/v) ethanol achieved the highest recovery rate of anthocyanins at 79.6%.

Conclusion: The mathematical models established in this study can be used in designing a pilot/industrial- scale column for the separation and concentration of anthocyanins from muscadine juice pomace. © 2018 Society of Chemical Industry.