Optimum Extraction of Flavonoids from Broccolini Leaves Using Response Surface Methodology

Broccolini (Brassica oleracea Italica × Alboglabra) is a hybrid of broccoli and kai-lan, Chinese broccoli. To date, no information is available on the extraction of flavonoids from Broccolini. In this study, an efficient ultrasonic-assisted extraction technique was developed to extract flavonoids from Broccolini leaves. The operating parameters were optimized using Box-Behnken design combined with response surface method. The analysis of variance showed that the response surface model fits very well with the actual situation. Based on the response model, the optimal conditions were determined as follows: extraction temperature 60 oC, ethanol concentration 70% and solid to liquid ratio 1:27. Under the optimal conditions, the maximum response value of yield (11.96 mg/g dry weight) was consistent with the experimental value (11.95 mg/g dry weight), demonstrating that large amounts of flavonoids can be efficiently extracted from Broccolini leaves using ultrasonic-assisted method although the process needs further optimization along with the development of purification method for food applications.