Abstract: The effect of enlargement treatment on total phenols and antioxidant activities of red globe grapes were determined in this study. The phenolic compounds and antioxidant activities were investigated during the berry growth and maturation after enlargement treatments. The difference between the treatment and the control, the correlation coefficients between phenolic compositions and antioxidant capacity, as well as the correlation coefficients among different methods for quantifying antioxidant capacity were analyzed based on DPS. The results showed that the content of total phenols and antioxidant activities of red globe grapes could be increased by enlargement treatments. The effect of enlargement treatment on total polyphenols, total flavonoids, total flavanols, cupric reducing power, potassium ferricyanide reducing power were higher than on DPPH radical scavenging capacity, ferrous ion chelating capacity and hydroxyl radical scavenging activity. The phenolic compounds had a significant positive correlation with cupric reducing power and potassium ferricyanide reducing power, but a significant negative correlation with hydroxyl radical scavenging activity. Both DPPH radical scavenging capacity and ferrous ion chelating capacity had no positive correlation with phenolic compounds. A significant positive correlation between cupric reducing power and potassium ferricyanide reducing power, and positive correlation between cupric reducing power and DPPH radical scavenging capacity were observed. The potassium ferricyanide reducing power and cupric reducing power had a significant negative correlation with hydroxyl radical scavenging activity.

Key words: table grape, enlargement treatment, phenolic compounds, antioxidant activity