Total phenolics, quercetin glycosides and antioxidant activity in organic and conventional orchards in three apple cultivars during fruit growth

Aim of study: To evaluate whether organic and conventional management practices, cultivar and fruit growth stage affect total phenolic content, antioxidant activity and quercetin glycosides in apples of three cultivars. Area of study: The trials were conducted in commercial orchards located in Chimbarongo, O’Higgins Region, Chile. Material and methods: Two types of orchard management (organic and conventional) were studied in three apple cultivars: Gala 'Brookfield', Granny Smith and Fuji 'Raku Raku'. Total phenolic content, antioxidant activity and quercetin glycosides were evaluated according to management practices, fruit growth stage, cultivar, fruit weight and skin surface. Data were analyzed statistically using a truncated multiple regression model. Main results: No differences were found between organic and conventional management regarding polyphenol concentration and antioxidant activity, except for specific quercetin glycosides. However, significant differences were observed between cultivars in both variables, as well as in fruit development throughout the season, which showed a significant dilution of polyphenols and antioxidant activity as the fruit grew. Research highlights: Cultivar and fruit growth stage were decisive in total phenolic content, glycosidic quercetins and apples antioxidant activity. Conventional and organic management practices were significant for quercetin glycoside concentration, which is the main polyphenol in apples.