Optimization of combined extraction and separation of pectins and polyphenols from apple pomace

In order to investigate the optimal process conditions for the combined recovery of pectins and polyphenols from apple pomace of apple juice by-product, the dried apple pomace was extracted with acid method and separated by a hydrophobic styrene macroporous resin. The factors affecting extraction yield, including pH value, temperature, extracting time and solid/liquid ratio were analyzed to optimize the co-extraction technologies. The evaluation index included extraction rate on the yield of pectins and polyphenols, and separation rate on the polyphenol adsorption, pectin adsorption and pectin chroma. The different extraction technologies and six macroporous resins were evaluated using the method of multiple attribute decision making (MADM) algorithm based on interval number. The optimal conditions of combined extraction were obtained with pH value 2.0, temperature 95℃, time 1.5 h and solid/liquid ratio 1:20 (g/mL). The mean pectin and polyphenol yields were 196.49 and 10.98 mg/g respectively, which possessing 92.28% and 85.92% of the highest single extraction yields. The optimal macroporous resin was XDA-5 for separation. According to the optimal separation conditions, the recovery of pectins and polyphenols were 98.32% and 92.15% of extraction sample. The results showed that application of MADM in the technology optimization can provide a reference for industrial production of recovery pectins and polyphenols from apple pomace simultaneously.