Influence of Shade Netting on the Chemical Properties and Antioxidant Activity of Raspberries and Blackberries from the South-East Region of North Macedonia

The effects of shade netting on the morphological and chemical composition (organic acids, sugars, total polyphenols, total and certain anthocyanins, proanthocyanidins) and in vitro antioxidant activity of raspberries and blackberries was conducted in the southeastern region of the Republic of North Macedonia. HPLC analysis confirmed a significant effect of shading nets on the amount of the most dominant anthocyanin in blackberries and raspberries. The amount of cyanidin-3-O-glucoside in blackberries covered with shading nets was significantly higher in comparison to the amount of the same anthocyanins in uncovered blackberries. The same tendency was observed for cyanidin-3-O-sophoroside for covered and uncovered raspberries from 2023. However, an opposite relationship was noticed for total anthocyanin content in favor of uncovered blackberry and raspberry from 2023. From all examined organic acids, the amount of acetic acid was the most affected in covered raspberries. The shade netting had a significant influence on polyphenolic content (such as high molecular proanthocyanidins, total and particular anthocyanins), the amounts of sugars (glucose and fructose), and organic acids as well as the intensity of color in blackberry and raspberry. Although net shading significantly influenced particular phenolic compounds presented in examined berry fruits, antioxidant activity was weakly correlated to this environmental change.