Thermosonication of Broccoli Florets Prior to Fermentation Increases Bioactive Components in Fermented Broccoli Puree

The aim of this study was to compare the effects of thermosonication (18 kHz at 60 degrees C for 7 min) pre-treatment with thermal treatment alone (60 degrees C for 7 min) of broccoli florets prior to pureeing and fermentation on selected bioactive components of fermented broccoli puree. Both thermal and thermosoncation pre-treatments significantly increased the rate of acidification of broccoli puree compared to control untreated broccoli puree, with the time to reach pH 4 being 8.25, 9.9, and 24 h, respectively, for thermally treated, thermosonicated, and control samples. The highest sulforaphane yield of 7268 mu mol/kg dry weight (DW) was observed in the thermosonicated samples, followed by 6227 mu mol/kg DW and 3180 mu mol/kg DW in the thermally treated and untreated samples, respectively. The measurable residual glucoraphanin content was 1642 mu mol/kg DW, 1187 mu mol/kg DW, and 1047 mu mol/kg DW, respectively, in the thermonsonicated, thermally pre-treated, and control fermented samples, indicating that pre-treatment specially by thermosonication increases the extractability of glucoraphanin. The higher sulforaphane yield in the thermosonicated and thermally pre-treated samples could be due to increased extractability and accessibility of glucoraphanin and interaction with myrosinase in addition to the inactivation of epthiospecifier protein (ESP), which directs conversion away from sulforaphane into sulforaphane nitrile.

Automated summary

The effects of thermosonication and thermal treatment on the bioactive components of fermented broccoli puree were compared in this study. Both treatments increased the rate of acidification and the yield of sulforaphane in the broccoli puree. The highest yield of sulforaphane was observed in the thermosonicated samples, indicating increased extractability and accessibility of glucoraphanin.