The phenolic content and antioxidant activity of the aqueous and hydroalcoholic extracts of hops and their pellets

摘要

The goal of this study was to investigate how three commonly used systems (water, 50% methanol and 50% ethanol) affected the yields of phenolic substances and the antioxidant capacity of extracts prepared from hops (cv Magnum and Marynka) and their pellets (T90 and T45). The total phenolic (TPC) and total flavonoid contents (TFC), as well as antioxidant activity (ABTS~(+.) scavenging, reducing power and metal chelating activity) of the hydroalcoholic extracts were found to be significantly higher than those of aqueous extracts. Extraction using 50% ethanol produced the highest yield of flavonoids. In turn, aqueous-methanol extracts were a better source of chlorogenic acid. No significant differences in terms of TPC and TFC were found between extracts prepared from hops and their pellets when water was used for extraction. Aqueous-ethanol extracts of T45 pellets, regardless of the hop variety, exhibited higher TFC compared with those of T90 pellets. For aqueous and aqueous-methanol extracts, such a tendency was not observed. Extraction with water revealed that cv Marynka hops and pellets had higher TPC than those of cv Magnum, which resulted in their better antioxidant potential. Hydroalcoholic extracts, regardless of the type of alcohol and hop product, did not differ significantly in terms of antioxidant activities.