Influence of pectin and rebaudioside A on the stability of anthocyanins and antioxidant activity of roselle (Hibiscus sabdariffa L.) juice
The dried calyx of the roselle flower (Hibiscus sabdariffa L.), which is commonly used for consumption as juice, has a high content of anthocyanins, natural compounds known for their antioxidant activity. Nevertheless, anthocyanins are unstable and susceptible to degradation, particularly during heating and storage. This research thus aimed to investigate the influence of pectin and rebaudioside A additions and storage temperature on anthocyanin stability and antioxidant activity of roselle juice. Roselle juice was prepared from dried calyx and extracted with water (1:10) at 50°C for 30 min. Four sets of sample solutions containing pectin, rebaudioside A and preservative were analyzed during storage: roselle juice (J), roselle juice with 1% pectin (PJ), roselle juice with 0.03% rebaudioside A (RJ), and roselle juice with 1% pectin and 0.03% rebaudioside A (PRJ). All samples were heated at 63°C for 30 min, and stored in amber glass at cold (4°C) or ambient (30°C) temperature for 10 weeks. Anthocyanin content, antioxidant capacity, and total polyphenol content were measured weekly. Samples J, PJ, RJ and PRJ exhibited anthocyanin content of 728.32±33.08, 681.10±9.16, 734.17±37.00 and 660.79±10.45 mg L-1, respectively. After storage for 10 weeks, all samples showed significantly high rates of degradation when kept at ambient temperature, compared with the 4°C storage (p≤0.05). Half-life (t1/2) times of anthocyanins of sample PRJ increased by 9.82% (at ambient temperature) and by 26.09% (at 4°C). From this research, additions of pectin 1% and rebaudioside A 0.03% help to stabilize anthocyanins of roselle juice. Moreover, the juice should be kept at 4°C to maintain the stability of anthocyanins in roselle juice for optimum health benefits.
Puangpraphant, S., Chantasuwanno, C., Rinthapol, N. and Heinchasri, P. (2017). Influence of pectin and rebaudioside A on the stability of anthocyanins and antioxidant activity of roselle (Hibiscus sabdariffa L.) juice. Acta Hortic. 1179, 277-284
Hibiscus sabdariffa L., anthocyanin stability, pectin, rebaudioside A, antioxidant activity