Studies on the extraction of Jerusalem artichoke tuber phenolics using microwave-assisted extraction optimized conditions
Newlove Akowuah Afoakwah, Yongsheng Zhao, William Tchabo, Ying Dong, John Owusu, Gustav Komla Mahunu
Abstract
Microwave-assisted extraction (MAE), which is a known method for the extraction of phenolic compounds from plants, was employed to extract the polyphenols in Jerusalem artichoke tuber (JAT) using response surface methodology optimized conditions of microwave power (MP), extraction-time (TE) and temperature (Temp). The MAE was used to improve polyphenols extraction yield from JAT. The ethanolic extracts of JAT obtained by MAE were quantitatively analyzed for total polyphenol content (TPC), total flavonoid content (TFC) 2, 2′-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP). The optimal conditions obtained were as follows: Temp of 79.18°C, TE of 11.96 min, and MP of 13.49 W. Based on these conditions, the extraction yield of TPC, TFC, % DPPH and FRAP could reach 4483.33 mg GAE/kg, 2731.59 mg RE/kg, 82.69 % and 2.65 mmol/L respectively with a predicted general-desirability value of 0.82. DPPH (r = 0.972) and FRAP (r = 0.982) significantly (p < 0.05) correlated to TPC suggesting that TPC was the main phenolic contributing to the antioxidant activity. The extraction yield recorded was higher than that of the liquid and ultrasound extraction methods.