Mircowave-Assisted Extraction of Phytochemical Constituents in Roselle (Hibiscus sabdariffa L.)

Abstract

Roselle (Hibiscus sabdariffa L.) is natural source of valuable components such as phenolics, flavonoids and anthocyanins. Anthocyanin is normally used in the food technology to replace synthetic pigments as well as medicinal properties due to antioxidants. Microwave irradiation is a feasible green solvent extraction method receiving great attention as it utilizes solvent at elevated temperature and controlled pressure conditions. Microwave extraction emerges as a promising inexpensive, simple and efficient technique. In our research, various variable like microwave power (20, 40, 60, 80, 100 W), microwave frequency (10, 20, 30, 40, 50 GHz), the microwave irradiation duration (5, 10, 15, 20, 25 min), liquid to solid ratio (water: material, 2:1, 3:1, 4:1, 5:1, 6:1), extraction temperature (50, 55, 60, 65, 70°C), number of extraction cycles (1, 2, 3, 4, 5) influencing to the microwave-assisted extraction of phytochemicals in roselle (Hibiscus sabdariffa L.) calyx were thoroughly examined. Total total phenolic (mg GAE/ 100 g), total flavonoid (mg GE/ 100 g), anthocyanin (mg/100 g) were key indicators to define the optimal variable. Our results revealed that microwave power at 80 W, frequency 40 GHz, duration 15 min, liquid to solid ratio 4:1, temperature 55°C, 4 cycles of extraction were appropriate for extraction of phytochemical components inside roselle (Hibiscus sabdariffa L.) calyx.