Characterizing the phenolic constituents of U.S. Southeastern blackberry cultivars

Abstract

BACKGROUND: Georgia’s small fruit sector is important to the state’s agricultural economy, and is seeking ways to promote their fruits in the health and wellness market. Based on the hot, humid, climatic conditions of the U.S. Southeast, three blackberry varieties, namely ‘Navaho’, ‘Ouachita’, and ‘Kiowa’, can grow, but a complete characterization of their antioxidant phenolic constituents has not been reported. OBJECTIVE: This study aims to investigate the phenolic compounds and antioxidant activities in U.S. Southeastern erect-type blackberry cultivars of commercial significance. METHODS: Phenolics from blackberries were isolated, separated, and elucidated both qualitatively and quantitatively by various chromatographic means, including HPLC–ESI–MS and MALDI–TOF–MS. RESULTS: Delphinidin-3-O-glucoside, malvidin-3-O-glucoside, quercetin-3-O-glucoside malonate, and propelargonidin B-type dimer were present in the Southeastern blackberries, which have not been found in any major U.S. cultivars. MALDI–TOF–MS analysis revealed a distinctive ellagitannin profile among the cultivars, and identified 5 additional ellagitannin compounds that were not elucidated by HPLC–ESI–MS.The detection of the propelargonidin B-type dimer revealed that the flavan-3-ols of blackberries are not limited to (epi)catechin-based compounds. CONCLUSIONS: U.S. Southeastern erect-type blackberry cultivars grown in Georgia showed distinct phenolic profiles and antioxidant activities from those of Pacific Northwestern cultivars.