Analysis of antioxidant capacity and polyphenol content of goji fruit products available on the European market

Abstract

The berries of Barbary wolfberry (Lycium barbarum L.) are used in alternative medicine as a nutraceutical. However, it has been shown that specific therapeutic effects are observed only in the very high concentrations of defined active ingredients from strictly selected phytochemical species of Lycium. Therefore, this study was carried out to compare the antioxidant properties and the content of polyphenols and flavonoids in dried berries, juices, and capsules containing goji berry extract. To determine the antioxidative potential of the tested products, methanol extracts of DPPH radical were employed, while to determine the polyphenol content the Folin-Ciocalteu reagent was used. The flavonoid content was determined using Dowd colorimetric method. This study showed that the dried goji berries were characterized by the highest content of polyphenols and flavonoids and having the highest antioxidant activity from all analyzed products. The significantly lower concentrations of studied components were observed in juices and the lowest in capsules. However, on a per-dose basis, the highest concentrations were observed for juice.