Effect of high-pressure homogenization on the extraction of sulforaphane from broccoli (Brassica oleracea) seeds

High-pressure homogenization (HPH) has the potential to improve the exaction yield of bioactive compound from food and food waste. This study investigated the use of HPH or microfluidization as an alternative assisted method for sulforaphane extraction from raw broccoli seeds. The mean particle size, morphological characteristics, and extraction yields of all samples processed at different HPH pressure levels (3000-23,000 psi) and passes (1–5) were examined. After HPH, the particle size of broccoli seeds was reduced 2–10 times and the particle size distribution pattern also changed from bimodal to unimodal with increasing pressures and number of passes. The highest sulforaphane content obtained with HPH at 5000 psi and 5 passes was 2199 μg sulforaphane/g broccoli seeds, which is 3 times more than the control one. Particular interest was given to the relationship between sulforaphane yield and particle size. Generally, the extraction yield increased with decreasing particle size; however, excessive size reduction did not necessarily result in significant increase in sulforaphane content. In addition, the pressure is not the higher the better (<8000 psi, 55 MPa). Scanning electron morphology (SEM) also confirmed that cell rupture and cell walls breakage occurred during the HPH process.