Adsorptive recovery of polyphenols from apple pomace

Abstract

This study was carried out to investigate the influence of different operating parameters such as pH, amount of adsorbent, temperature, adsorbent-to-apple pomace (AP) ratio, and type of elution solvent on the recovery of polyphenols from AP. The study used a non-functionalized macroporous polymetric food-grade resin (Amberlite FPX66) as an adsorbent for the recovery of polyphenols from apple pomace (AP) on a laboratory scale. Adsorption was carried out using a continuous process and desorption was carried out using a batch process. The adsorption on the resin was influenced by the pH and the AP: resin ratio. At pH 4, for the first 30 min, about 94% of polyphenols were adsorbed onto the 5 g resin, and about 77 and 82% of the compounds were adsorbed onto the resin at pH 2 and pH 7, respectively. After 150 min, about 86% of polyphenols were adsorbed onto the 5 g resin, whereas the polyphenols adsorbed on the 10 g and 20 g were 71 and 64%, respectively. However, for the first 30 min, 10 g and 20 g polyphenols were fully adsorbed onto the resin. Desorption studies were carried out using a resin that was taken from the batch process. Elution for the desorption studies was carried out using different solvents (water, ethanol, and isopropanol) at different temperatures ranging from 40 to 180 °C to determine their influence on the recovery of individual polyphenols. Isopropanol showed more recovery for polyphenols at 40 °C compared to when water and methanol were used. The study shows that Amberlite FPX 66 has the capability to recover polyphenol, however, the operational temperature should be considered.