Technology optimization of polyphenols extraction from apple pomace

To optimize conditions of polyphenols extraction from apple pomace and obtain the relationship between technology and polyphenols, microwave-assisted extraction was applied for polyphenols extraction from apple pomace in this study. The factors (particle size of apple pomace, liquid/solid ratio, ethanol concentration, microwave power and microwave treatment time) affecting extraction yield, were analyzed to optimize the extraction technologies. The evaluation index included total content of polyphenols, flavone, procyanidins and antioxidant activity. The extraction technologies of polyphenolic compounds from apple pomace were evaluated using evidence theory. According to the belief function, plausibility function and evidential ratiocination algorithms, the utility interval number of each extraction technology was obtained. Furthermore, the rank order of all technologies and the optimal extraction technology were attained. The results showed that the optimal conditions were as follows: materials through 60 mesh sieve, liquid to solid ratio of 30 mL/g, ethanol concentration of 60%, microwave power of 600 W, extraction time of 70s. Under these conditions, the extraction rate of apple polyphenols was 213.83 mg/100g, flavone was 83.21 mg/100g, procyanidins was 52.79 mg/100g, and EC50 was 3.71 mg/100mL. The study analysis showed that the evidence theory was efficient for polyphenols extraction from apple pomace.