The Effect of Processing Conditions on the Bioactive Compounds, Aroma Profile and Sensory Attributes of Wine from Hibiscus sabdariffa

Hibiscus sabdariffa (H. sabdariffa) is a rich source of bioactive phytochemicals with potential health benefits. Based on its reported use in folk medicine for the treatment of hypertension and recently type 2 diabetes, the plant has gained considerable commercial importance as a functional food. Three varieties of H. sabdariffa were analyzed for their phytochemical content and inhibitory potential on carbohydrate-digesting enzymes as a basis for selecting a variety for wine production. The dark red variety was chosen as it was highest in phenolic content and partially inhibited α–glucosidase (maltase), with delphinidin 3-O-sambubioside, cyanidin 3-O-sambubioside and 3-O-caffeoylquinic acid accounting for 65 % of this activity. None of the varieties significantly inhibited α–amylase. Regarding H. sabdarifa wine, the effect of fermentation (20 and 30 ˚C) and ageing (6, 15 and 30 °C) temperatures on the phytochemical composition and bioactivity of Roselle wine was investigated for a period of 40 days and 12 months respectively. The main change in phytochemical composition observed during fermentation was the hydrolysis of 3-O-caffeolquinic acid and the concomitant increase of caffeic acid irrespective of fermentation temperature. Wine fermented at 20 ˚C was slightly more active for α–glucosidase inhibition with more fruity aromas, but there were more flowery notes at 30 ˚C. Although ageing temperature did not produce an obvious trend in concentrations of most of the volatiles analysed, its impact was clearly demonstrated in the final concentrations of diethyl succinate which increased with higher ageing temperature. The data on the overall quality rating of roselle wine by a sensory panel showed that neither fermentation nor ageing temperatures produced any significant difference (p ≥ 0.05) in the wine samples. This study demonstrates that processing of H. sabdariffa into wine represents a promising alternative to expanding the functional properties of this crop.