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Heating decreases epithiospecifier protein activity and increases sulforaphane formation in broccoli
Nathan V Matusheski1, John A Juvik, Elizabeth H Jeffery
1Department of Food Science and Human Nutrition, University of Illinois, 499 Bevier Hall, 905 South Goodwin Avenue, Urbana, IL 61801, USA.
Phytochemistry
|June 9, 2004
Summary
Heating broccoli to 60°C enhances the formation of sulforaphane, a potent anticarcinogen, by reducing inactive sulforaphane nitrile. This heat-induced change optimizes the yield of beneficial compounds from broccoli.
Area of Science:
- Food science
- Biochemistry
- Cancer prevention
Background:
- Sulforaphane, a key anticarcinogen in broccoli, is derived from glucoraphanin via myrosinase action.
- Crushing broccoli at room temperature yields low sulforaphane and high amounts of inactive sulforaphane nitrile.
- Epithiospecifier protein (ESP) controls nitrile formation, influenced by temperature.
Purpose of the Study:
- To investigate the impact of heating broccoli on sulforaphane and sulforaphane nitrile production.
- To determine the presence and activity of ESP in broccoli.
- To correlate heat-induced changes in ESP activity with sulforaphane content and bioactivity.
Main Methods:
- Broccoli florets and sprouts were heated to various temperatures (60°C, 70°C+) before homogenization.
- Sulforaphane and sulforaphane nitrile levels were quantified.
- ESP activity was assessed by measuring its heat-induced loss.
- Bioactivity was measured by quinone reductase (QR) induction in cultured cells.
Main Results:
- Heating broccoli to 60°C significantly increased sulforaphane and decreased sulforaphane nitrile formation.
- A parallel decrease in ESP activity was observed with reduced sulforaphane nitrile.
- Higher temperatures (70°C+) reduced both products in florets but not sprouts.
- Increased sulforaphane formation correlated with enhanced QR induction.
Conclusions:
- Controlled heating of broccoli optimizes sulforaphane production by inactivating ESP.
- A 60°C heating step is effective in maximizing beneficial sulforaphane yield from broccoli.
- Broccoli sprouts may offer a more heat-stable source of sulforaphane compared to florets.