Ultrasonic-assisted modifications of macroporous resin to improve anthocyanin purification from a Pyrus communis var. Starkrimson extract

The present study presents an attempt to modify the surface properties of macroporous resins (MRs) in order toimprove anthocyanin adsorption and desorption from Pyrus communis var Starkrimson fruit peel extract. Anumber of MRs were tested to optimise the ultrasonic-assisted adsorption (UAA) conditions; including ultrasonic power (100–400 W), resin-to-extract ratio (1–3 g/50 mL) and temperature (20–40 °C). Similarly, varying ultra-sonic-assisted desorption (UAD) conditions were optimised; including ultrasonic power (200–600 W), resin-to-solvent ratio (1–4 g/50 mL), ethanol concentration (60–90% v/v) and temperature (20–40 °C). The Amberlyst 15(H) cationic resin was found to be superior to the other tested resins. The maximum adsorption capacity (659 μg/g) of cyanidin 3-galactoside (Cy 3-gal) was achieved under the optimised UAA conditions (400 W, 20 °C and 1 g/50 mL), while 616 μg/g of Cy 3-gal was recovered under the optimised UAD conditions (582 W, 1 g/50 mL, 60%and 20 °C). Moreover, titratable-acid and total-sugar contents were found to be significantly lower under UAAthan under conventional-assisted adsorption (CAA). ANOVA revealed that process factors had significant effectson the Cy 3-gal purification, as depicted by their linear, quadratic and interactive effects. While anthocyanin adsorption was found to be significantly improved at lower ultrasonic power, higher power promoted the desorption process. Adsorption under optimized UAA conditions followed pseudo second-order kinetics and multilayer adsorption (Freundlich isotherm) onto the Amberlyst 15 (H) resin surface was observed. The particle-size distribution curve and scanning electron microscopic images also revealed higher resin-surface roughness,peeling and the appearance of pores on the surface under ultrasonication. This is thefirst study to use ultra-sonication to modify a cationic exchange resin for the improvement of Cy 3-gal purification from a fruit extract.This study can recommend the use of ultrasonication as a low-cost green technique that can improve macro-porous resin characteristics for better purification of compounds from an extract.