Comparative study of phytochemical extraction using hydrogen-rich water and supercritical fluid extraction methods

Abstract

Phytochemicals are widely found in agri-food wastes. The extraction of ‎phytochemicals was evaluated using hydrogen-rich water extraction (HRW-E) and supercritical fluid ‎extraction (SFE) methods from different plant wastes (tomato peel, orange carrot, green ‎apple ‎peel, lemon peel, red cabbage). Total phenolic content (TPC), total ‎flavonoid content (TFC), total anthocyanin, and antioxidant activity (DPPH and ABTS) were ‎highest in HRW-E samples compared to SFE and pure water extraction for all plant wastes. The percent increase (%) ranged between 5.14 and 12.06 and 22.27–49.62 (TPC), 1.32–35.59 and ‎‎16.01-‎‎‎53.03 (TFC), 18.18–53.19 and 80.53–390.1 (anthocyanins), 2.21–22.37 and 9.03-‎‎142.46 ‎‎‎(DPPH), and 1.16–7.49 and 14.47–28.05 (ABTS) for SFE and HRW-E samples, ‎respectively. ‎HRW-E was more potent than SFE for extraction of all phytochemical types from ‎all plant wastes. Non-flavonoids, e.g., phenolic acids (gallic acid, chlorogenic acid, p-‎coumaric acid, trans-ferulic acid‎) and flavonoids (catechin, epicatechin, and rutin)‎, were extracted ‎better by HRW-E than ‎‎SFE for different plant wastes. ‎The HRW-E method is recommended to researchers and processors‎ as an extraction method for phytochemicals due to its simplicity, low cost, not requiring additional equipment or ‎energy source, non-toxic solvent use, green properties of the product and for the environment, as well as higher extraction ‎‎efficiency.‎