Polyphenols Content and Antioxidant Capacity of Goji Fruits (lycium Chinense) as Affected by the Extraction Solvents

Antioxidants are substances which, when present in low concentrations, compared with that of an oxidisable substrate, significantly delay or prevent oxidation of the substrate (Halliwell & Gutteridge 1989). The most abundant antioxidants in fruits and vegetables are polyphenols and vitamins, especially vitamin C. Vitamins A, B and E and carotenoids are present to lesser extent in some fruits. The aim of this paper was to study the antioxidant capacity and total polyphenols content of fresh and dried goji fruits (L. chinense) using various solvents for extraction from the samples. The examinations have been carried out both at the fresh goji fruits (L. chinense) harvested at maturity of consumption as well as at sun-dried fruits (dry matter content of 85.31%). We also determined the content of these fruits in different chemical compounds which affect the antioxidant capacity, such polyphenols and vitamin C. The nature and the concentration of the solvent used for extraction affects the total polyphenols content and the antioxidant activity of goji berries, which is in accordance with previous data. Extraction with alcohol 80% as well as with hydrochloric acid 2% have resulted in the highest values of the polyphenols content while the highest antioxidant activity was found by using as solvent the hydrochloric acid 2%, normally used for vitamin C determination.