Evaluation of antioxidant activity of alcohol-free Moru wine using on-line HPLC

Abstract

In this study, the chemical composition and antioxidant activities of Moru wine and alcohol-free Moru wine were evaluated. To prepare the alcohol-free analogue, Moru wine was subjected to either atmospheric distillation (NA-AD) or vacuum distillation (80 mbar, 55℃, NA-VD). Among the three different preparations of Moru wines, namely, Moru wine, NA-AD, and NA-VD, the total acidity was the highest in NA-VD, while the soluble solid content was the highest in Moru wine. The total phenolic content, total flavonoid content, and ABTS radical scavenging activity were the highest in NA-AD. The three different preparations of Moru wines were examined by an on-line high-performance liquid chromatography (HPLC)-2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS)-based assay to identify the compounds responsible for the radical scavenging activity of wines. The results obtained for NA-AD and NA-VD in the on-line screening HPLC-ABTS assay were similar. At least 10 different compounds, namely, gallic acid, protocatechuic acid, chlorogenic acid, vanillic acid, caffeic acid, syringic acid, t-ferulic acid, rutin, naringin, and t-cinnamic acid, were identified from Moru wine, NA-AD, and NA-VD. Gallic acid (10.35-24.69 μg/mL) and syringic acid (9.29-43.98 μg /mL) were found to be the major polyphenols in Moru wine, NA-AD, and NA-VD.