Microwave-assisted extraction of sulforaphane from white cabbages: Effects of extraction condition, solvent and sample pretreatment

Sulforaphane is one of the most potent food-derived anticarcinogens and is abundantly found in Brassica vegetables, including cabbages. Due to its importance an ability to effectively extract sulforaphane from its source is desirable. This work investigated the feasibility of using microwave-assisted extraction (MAE) to extract sulforaphane from cabbages. The effects of various parameters, which are the type of solvent (dichloromethane and water), set microwave power (130, 260 and 390 W) and extraction time, on the extraction yield of sulforaphane were investigated. In addition, since it was previously shown that partially dried cabbages contain higher sulforaphane content than fresh cabbages, the effect of partial drying prior to MAE on the extractable amount of sulforaphane was investigated. A comparison between MAE and conventional extraction was also made. The results showed that MAE was more effective than the conventional extraction as the former led to higher yield of sulforaphane in a much shorter extraction time. There were no significant differences in the highest extractable sulforaphane contents from the fresh and semi-dried samples. Use of different solvents also did not lead to any significant effect on the MAE of sulforaphane, either from the fresh or semi-dried sample.

► MAE provided higher extraction yield than conventional method in much shorter time.
► Similar MAE yield could be obtained using either fresh or semi-dried sample.
► Use of different solvents did not lead to significant effect on extraction yield.