This 2021 study combined ultrasound and heat to increase broccoli compounds:
“A large proportion of broccoli biomass is lost during primary production, distribution, processing, and consumption. This study evaluated thermosonication for pre-treatment of broccoli florets to enhance enzymatic conversion of glucoraphanin (GR) into bioactive sulforaphane (SF).
Our results showed that a combination of ultrasound with heat treatment (at 50 and 60 °C for 5 and 7 min) improved release of GR from broccoli matrix over and above heat treatment alone. This could be due to mechanical disruption of plant cell wall and plant matrix, which enhances release of intracellular content.
The highest residual level of both GR (126.3% increase) and sulforaphane was observed after thermosonication at 60 °C for 7 min. It can be concluded that:
- Measured levels of glucoraphanin in untreated broccoli using current methods gives only an indication of the amount of easily accessible and extractable glucoraphanin in broccoli; and
- Processing of broccoli by heat and ultrasound enables release of possibly bound glucoraphanin and enhances conversion to sulforaphane.
Higher sulforaphane yield was observed under conditions of significant myrosinase inactivation. This could be attributed to:
- Inactivation of ESP [epithiospecifier protein], providing a suitable condition for synthesis from GR to SF as opposed to SF-nitrile; and/or
- Increased in situ residual myrosinase activity at elevated temperatures; and/or
- Increased release and accessibility of GR.
Maximum SF content among studied conditions was achieved using thermosonication treatment at 60 °C for 7 min, which represented a 192.6% increase compared to untreated broccoli florets. That was 15.8% higher than thermal treatment, indicating the potential of thermosonication for enhancing sulforaphane yield over and above effects of heat.”
https://www.mdpi.com/2218-273X/11/2/321/htm “Thermosonication for the Production of Sulforaphane Rich Broccoli Ingredients”
I mentioned in Week 34 how broccoli sprout experts tried to smear a Microwave broccoli to increase sulforaphane levels finding of more glucoraphanin with increasing temperatures after microwaving. This study measured a similar effect of glucoraphanin increases using two techniques:
“For GR extraction two methods were initially examined: aqueous extraction or methanolic extraction. We wanted to compare effects of using different extraction solvents to evaluate whether levels of extractable GR were influenced by the type of solvent.
The difference between GR content of aqueous and methanolic extracts was not statistically significant.”
Thermosonication isn’t suitable for home use. Microwaving is.
A microwave can’t keep contents at a constant 60° C for seven minutes, though. Optimizing myrosinase activity is also a consideration for increasing broccoli sprout compounds at home.