Effect of pasteurisation and storage on bioactive compounds in Roselle (Hibiscus sabdariffa) from a beverage perspective

Hibiscus Sabdariffa (Roselle) is popular as a beverage in countries within Africa, Asia and South America. Benefits of Roselle, demonstrated in vivo, include lowering cholesterol and reducing raised blood pressure. These benefits have been attributed to Roselle phenolic compounds; Anthocyanins in particular. This study monitors the effects of processing and storage life on these compounds in a Roselle extract. An aqueous extract of Roselle (90oC,20mins) was pasteurised (85oC,25mins) and stored for 90days at room(21oC), refrigeration(4oC) and freezing(-21oC) temperatures and analysed for total phenolic (TP) content, total anthocyanins (TA) and antioxidant properties at different time points. Initial values for TA, antioxidant capacity (FRAP) and TP contents were 42.3±4.57 mg Cyanidin-3-Glycoside/L Roselle extract, 140.23±21.42 g Ascorbic Acid Equivalent/L and 132.75±3.32 mg Gallic acid equivalent/L respectively. Overall, there was no effect of pasteurisation on TP, TA and antioxidant activity. However, there was a significant effect of storage temperature and time particularly evident extracts stored at room temperature; resulting in a 70% loss of TA from initial. There was also an effect of storage time on TA content and antioxidant capacity. Pasteurisation with cold temperature storage within 90 days did not result in significant changes in Roselle bioactive.