Goji berries (wolfberry) are a food product that contains many bioactive compounds, including polyphenols, amino acids, polysaccharides, carotenoids, and polyunsaturated fatty acids. The objective of the research study was to determine the antioxidative properties of ethanol and water extracts of freezedried Goji berries as well as the content of groups of compounds accounting for those properties. The raw materials used in the research study came from China and Uzbekistan. There were determined the contents of polyphenols, flavonoids, vitamin C, carotenoids, and sugars. The antioxidative properties were assessed using FRAP (Ferric Reducing ability), DDPH (1,1-diphenyl-2-picryhydrazyl radical), and ORAC (oxygen-radical absorbance capacity) methods. All the samples were characterized by a high content of ascorbic acid (2 ÷ 3 mg/g) and carotenoids (1 ÷ 2.6 mg/g). The content of polyphenols (ca. 11 mg GAE/g) and flavonoids (ca. 2.5 mg CAE/g) was high; however, their content as determined in the aqueous extracts was lower than in the ethanol extracts. All the samples were characterized by a high antioxidative activity. The results of measurements performed using the ORAC method showed the highest differences among the extracts. As for the ethanol extracts, the amount of Trolox assayed was about 1 mmol /g, and as for the aqueous extracts, it was 0.03 ÷ 0.1 mmol. The results of DPPH test also were also lower in the case of the aqueous extracts. The analysis made by the FRAP method showed no high differences among the samples. The analysis results demonstrate that the Goji fruit can be a dietary supplement to provide bioactive, antioxidatively acting compounds that have an effect on the proper functioning of the body.
Goji berry, Lycium barbarum, ascorbic acid, antioxidants, flavonoids