Optimization of polyphenols extraction from sweet potato peel: single factor versus chemometrics approach

Abstract

The study was aimed at optimizing the extraction conditions of phenolic compounds from an orange-fleshed cultivar of sweet potato peel using a single factor vis-a-vis chemometric experimental approach. The effectiveness of extracting antioxidants compounds using an aqueous medium (water) was compared to organic solvents. Water-to-peel, time of extraction and extraction temperature was established to have significant effects on the total antioxidant and scavenging activities. Optimal extraction variables of 60 ºC for 20 minutes, at a solvent-to-peel powder ratio of 100:7.5 mL/g was derived for the process. Approximately 157.0 g of peel powder was obtained from a kilogram of the dried potato peel using a simple but scalable method. The polyphenol isolate contained 31.39 % polyphenols and compared significant well with vitamin C and butylated hydroxytoluene (BHT) in terms of its antioxidant activities. In summary, this study used an aqueous medium as its extracting solvent, which offers a great prospect for future use in the extraction and purification of bioactive compounds from plant materials.