Stilbene, Ellagic Acid, Flavonol, and Phenolic Content of Muscadine Grape (Vitis rotundifolia Michx.) Cultivars

ABSTRACT

Stilbene, ellagic acid, flavonol, and phenolic compounds were analyzed in 19 muscadine cultivars and 2 muscadine selections. Analysis was carried out on muscadine fruit skin, pulp and juice partitions. The major phenolics in muscadine juice, pulp and skins were identified by their retention times and characteristic spectra. Quantification was made by calibration curves of external standards for each of the analyzed compounds: trans and cis resveratrol, trans and cis piceid, ellagic acid, myricetin, quercetin and kaempferol. Free and total ellagic acid was observed in muscadine juice of eight cultivars, in amounts up to 54.0 μg/g in ‘Ison’ and 56.0 μg/g in ‘Janet’. In the pulp, free ellagic acid was only observed in 3 cultivars, and total ellagic acid was observed in 8 cultivars in amounts up to 57.0 μg/g for ‘Janet’ and 77.0 μg/g for ‘Southland’. Also in pulp, trans-resveratrol was observed in two cultivars, ‘Eudora’ and ‘Janet’ in amounts of 0.9 μg/g and 4.3 μg/g respectively. In muscadine skin, free and total ellagic acid, myricetin, quercetin and kaempferol were observed in all 21 cultivars analyzed and trans resveratrol was observed in all cultivars except ‘Alachua’. Ellagic acid was the most abundant phenolic compound in muscadine grape skins. Total ellagic acid ranged from a low of 779.0 μg/g in ‘Tara’ to a high of 5,554.0 μg/g in ‘Southland’. The presence of ellagic acid and other nutraceutical compounds in muscadine grape could add value and marketability to the crop due to the possible health benefits. This southern specialty crop could fast become the next “super fruit”.