Abstract: The enzymatic extraction of sulforaphane from broccoli stems and leaves was optimized by one-factor-at-a-time method and response surface methodology. Scale-up experiments were carried out under optimized conditions, and the crude extract was purified by preparative high performance liquid chromatography (HPLC) and identified by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The results showed that the optimal extrac tion conditions were determined as follows: pH 5.0, temperature 35 ℃ and time 67 min. Under these conditions, the maximum yield of sulforaphane of 151.39 μg/g (on a dry matter basis) was obtained, which agreed with the predicted value (156.33 μg/g). The yield of purified sulforaphane was 28.62 mg from 200 g of broccoli powder, with a 94.52% recovery and 80.74% purity. The tandem mass spectrum and fragment ion information confirmed the substance as sulforaphane.

Key words: broccoli byproducts, sulforaphane, preparative high performance liquid chromatography, ultra performance liquid chromatography-mass spectrometry (UPLC-MS)