Potentially Bioactive Compounds and Sensory Compounds in By-Products of Several Cultivars of Blackberry (Rubus fruticosus L.)

This study aimed to determine the amounts of phenols, antioxidant activity, and sensory compounds in three commercial cultivars of blackberries popular in Lithuania: ‘Polar’, ‘Brzezina’, and ‘Orkan’. Blackberry pomace was analyzed by the spectrophotometric method for total phenolic content, total flavonoid content and radical-scavenging capacity using the DPPH• and ABTS•+ assays. The phenolic profiles, organic acids, and sugars were analyzed by HPLC. The Heracles II electronic nose, which is based on ultrafast gas chromatography, was used for the quantification of volatile organic compounds. The results show that the total phenolic content of blackberry pomace varied from 2380.60 to 2088.00 mg 100 g−1 and that the total flavonoid content varied from 161.29 to 148.10 mg 100 g−1, depending on the cultivar. A total of 14 polyphenols were also identified, with epigallocatechin and anthocyanin cyanidin-3-O-glucoside being quantified in the highest concentrations (7.28 to 9.72 and 6.19 to 9.79 mg g−1, respectively) and being the predominant phenolic compounds in the blackberry-pomace samples. The odor profiles of blackberry pomace from different cultivars varied. The main volatile organic compounds found in all blackberry pomace were 1-Nonanol and cis-3-Hexen-1-ol, are associated with herbaceous and citrusy aromas. All these results show the potential of using blackberry pomace to enrich food products with bioactive phytochemicals.