Abstract:Taking broccoli by products as raw material，isothiocyanate （ITC）of broccoli-by-products were extracted by the method of ultrasonic-assisted，and the ultrasonic treatment power，ultrasonic treatment time，extraction temperature，pH，solid-liquid ratio were invested.Based on the single factor tests，Box-Benhnken center composite experiment was carried out with four factors three levels to perform response surface analysis which put the extraction volume of ITC as the response values，and the antioxidant activity of the ITC was preliminarily explored.The results showed that，the optimal conditions were as follows：ultrasonic power was 63 W，ultrasonic treatment time was 16 min，extraction temperature was 40℃，and pH was 6.2.Under this condition，the extraction volume of ITC was 0.895 mmol/L，which was close to the measured value.The relative error between the actual values and predicted values was only 1.2%.In vitro antioxidant experiments showed that，the ability of ITC extracted from broccoli by-products to scavenge DPPH and ABTS+free radicals were 0.623 and 0.463 Trolox equivalents respectively.And the ability of ITC to reduce Fe3+was 0.573 Trolox equivalents.It showed that the optimized extraction of ITC had a good anti-oxidation function.