Phenolic and sensory profile of blackberries (Rubus l.) produced by conventional and organic agricultural practices

Blackberries are a rich source of polyphenols with high antioxidant activity; nevertheless, the impact of organic versus conventional agricultural practices on the phenolic and sensory profile is unknown. Therefore, the aim of this study was to compare the accumulation pattern of polyphenols (total phenolic compounds and total anthocyanins), soluble solids, antioxidant activity as well the sensory profile of two blackberries varieties "Loch Ness" and "Chester Thornless" grown under organic and conventional agricultural practices, at the same edaphoclimatic conditions. Both blackberry varieties, agricultural practices as well as their interaction, had a significant effect on the amount of soluble solids. For the total phenolic content, there was only a significant difference between the varieties, with no significant differences between the agricultural practices. Concerning to the total anthocyanins, it was observed a significant interaction between the varieties and agricultural practices. The antioxidant activity of the blackberries followed the same trend as that observed for the total phenolic compounds. Significant differences were only observed between varieties, with the “Loch Ness” variety showing the higher antioxidant activity and “Chester Thornless” variety showing the lowest antioxidant activity regardless the agricultural practice used. Results show that the effect of the agricultural practice on the chemical and sensory profile of blackberries was dependent on the genetic background of the variety and cannot be generalized.

The authors would like to thank the Company Delícias do Tojal, that supplied the blackberries. We appreciate the financial support provided to the CQ-VR Research unit in Vila Real (PEst-OE/QUI/UI0616/2014) and European Investment Funds by FEDER/COMPETE/POCI– Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.