Oana Emilia Constantin, Adelina Ștefania Milea, Carmen Bolea, Liliana Mihalcea, Elena Enachi, Dana Maria Copolovici, Lucian Copolovici, Florentina Munteanu, Gabriela Elena Bahrim, Gabriela Râpeanu
April 12, 2021
The impact of different extraction methods on bioactive compounds (total phenols and flavonoids) recovery from onion wastes recovered from the market was investigated. The results revealed a total polyphenol content from 25.19 ± 3.56 mg gallic acid equivalents/g for enzyme-assisted extraction (EAE) to 212.56 ± 1.18 mg gallic acid equivalents/g for supercritical extraction (SFE). The total flavonoid content registered from 108.36 ± 3.62 mg quercetin equivalents/g for EAE to 334.97 ± 19.41 mg quercetin equivalents/g for conventional solvent extraction (CSE). The antioxidant activity (404.93 ± 1.39 mM Trolox/g) for SFE was the highest compared to all the extraction procedures used. The chromatographic profiles were conducted at five primary compound identification (quercetin 7,4-diglycoside, quercetin 3,4-diglycoside, quercetin 4-glucoside, quercetin, and kaempferol) and GC-MS analysis allowed the identification of 26 compounds, manly identified in EAE. The results also revealed that the SFE method, as a non-invasive technique, recorded the highest concentration of bioactive compounds and antioxidant activity, confirmed by chromatographic profiles.