Blanching broccoli sprouts

Three 2022 papers of interest cited Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease. Let’s start with a fairly straightforward analysis of blanching broccoli sprouts to produce sulforaphane:

“We investigated the effect of blanching conditions to determine the optimal treatment that maximizes sulforaphane (SFN) content in broccoli sprouts. Broccoli seeds grown under controlled conditions were harvested after 11 days from germination and subjected to different blanching conditions based on a central composite design with temperature and time as experimental factors.

Optimum conditions were blanching at 61 °C for 4.8 min, resulting in 54.3 ± 0.20 µmol SFN/g dry weight, representing a 3.3-fold increase with respect to untreated sprouts. This is the highest SFN content reported for sprouts subjected to any treatment so far.

sfn heat response curve

Broccoli sprouts (20 g) were put in plastic bags, which were vacuum-sealed, and then subjected to time (3.4–11 min)–temperature (32–88 °C) combinations.

  • Blanching at 60 °C for less than 8 min resulted in the highest SFN content.
  • Above this temperature, SFN content decreases.
  • The exceptionally high values obtained in this work may be related to treatment, but also to broccoli cultivar and culture conditions.

Different broccoli tissues and developmental stages express different myrosinase isoforms, and catalytic properties of the enzyme may vary among different tissues. Myrosinase found in broccoli florets has an optimal temperature of around 40 °C, and considering myrosinases from other sources, this temperature may vary between 30 and 70 °C.” “Maximization of Sulforaphane Content in Broccoli Sprouts by Blanching”

This first study used heat-only techniques similar to the uncited Enhancing sulforaphane content. It similarly found a 60°C (140°F) myrosinase cliff as have many other uncited studies.

A second paper was a rodent study:

“We investigated the role of sulforaphane, a well-known NRF2 activator, on age-related mitochondrial and kidney dysfunction. Young (2–4 month) and aged (20–24 month) male Fischer 344 rats were treated with sulforaphane (15 mg/kg body wt/day) in drinking water for four weeks.

Sulforaphane significantly improved mitochondrial function and ameliorated kidney injury by increasing cortical NRF2 expression and activity and decreasing protein expression of KEAP1, a NRF2 repressor. Sulforaphane treatment did not affect renal NRF2 expression or activity and mitochondrial function in young rats.” “Age-Related Mitochondrial Impairment and Renal Injury Is Ameliorated by Sulforaphane via Activation of Transcription Factor NRF2”

A human equivalent to this second study’s daily dose was intolerable at (.162 x 15 mg) x 70 kg = 170 mg. I curated this study anyway just to show an example of negligible treatment effects in young animals even when a dose is too high for humans.

A third paper was a review that focused on sulforaphane and its analogs’ chemistry:

“Analysis of the Web of Science database shows that, since 1992, about 3,890 articles have been published on SFN, and over 5,600 on isothiocyanates. Its natural analogs include iberin, alyssin, iberverin, erucin, berteroin, cheirolin, and erysolin.

SFN is a biologically active, natural isothiocyanate found in cruciferous vegetables, and is non-toxic. It has been selected for phase I and II clinical trials, where it is administered in the form of an extract or broccoli sprouts. There are no differences in biological activity between SFN and its natural analogs, such as erucin or alyssin.

No synthetic analogs of SFN described in this review qualified for clinical trials. This is likely due to the toxicity of these compounds in higher doses.” “Sulforaphane and Its Bifunctional Analogs: Synthesis and Biological Activity”


6 thoughts on “Blanching broccoli sprouts

  1. Thank you for all you do with this blog. I learn so much from you.
    I wonder if the sulforaphane decreases over 60 degrees because the myrosinase gets destroyed over 60 degrees? I don’t think the glucoraphanin is damaged above 60 degrees, so you can just add back some myrosinase after you heat it. But just sticking to a 60 degree limit seems easier. To paraphrase something I think you have said: If you want more sulforaphane, just eat more sprouts/seeds.

    What I am doing now, as I am lazy, is:
    1: I sprout a combination 2/3 broccoli and 1/3 daikon radish.
    2: I microwave 40 grams of that (8 ounces) full power for 30 seconds.
    3: I add 20 more grams of the raw sprout mix (for the myrosinase) to the mix.
    4: I add some oil and vinegar and sprinkle Parmesan and chew well.
    It’s good! Do you think I am getting a healthy dose of sulforaphane?

    • Thanks for commenting David! Think your math is a little off, in that 40 grams is closer to 1.5 oz. Where do you get daikon seeds?
      Myrosinase is complicated. I read four studies on it yesterday, and don’t feel better informed about what a home sprouter can do.
      For example, would the same daikon cultivar have different myrosinase characteristics in its seeds, sprouts, or mature radish? That’s apparently the way it is with broccoli, without factoring in the different glucoraphanin contents of seeds, sprouts, and florets.
      What you’re doing looks good to me. It’s hard to know for sure without turning your kitchen into a lab. It was tempting to see thermostatic water baths on sale during Prime Day, though.

      • Thank you so much for the response! My math was not so much off as my explaining what I meant (maybe both were off). I weighed out 40 grams of sprouts and that filled an 8 ounce cup, so now I measure my sprouts by volume and not weight. I pretty much eyeball it now.
        I get Daikon Radish seeds on Amazon.
        I learned about Daikon Radish as a source of Myrosinase from Dr Albert Wright. Albert recommends white mustard as an exogenous source of Myrosinase, but yellow mustard seed or daikon radish are good too. I guess brown mustard is not a compatible source.
        You can find Albert on LinkedIn. He has a broccoli seed tea project ongoing.
        From what I have read, you can’t get too much sulforaphane (or better, I have not read you can get too much sulforaphane), so my idea is to just punch myself in the mouth with sulforaphane. I always have it before noon as it boosts NRF2 and NRF2 boost the circadian rhythm, and the circadian rhythm peaks between one and two pm. I don’t want to boost my circadian rhythm on the downstroke.
        Okay, I will shut up now 🙂 . Thanks again, Dave

        • Hi Dave! Here’s what Dr. Wright said in a comment to the longish Caution on broccoli seed erucic acid content?:
          “It is easy to say that there is more erucic acid in seeds compared to sprouts, so avoid seeds and eat sprouts. But the same is true of the glucosinolates and both substances are largely transferred to the sprouts as they take up more water so diluting both substances to more or less the same extent. I have been using a home made broccoli seed extract containing sulforaphane to reduce oxidative stress in neurons for Parkinson’s disease and have experienced good results so far. Seeds are more practical to use than sprouts when you are seeking to find the best dose range which has been my main difficulty. Doses based on animal trials, typically in the 100 µmol range which corresponds to 2-3 g of seeds seem to be too high. By trial and error I get the best results using a much smaller dose which corresponds to a range of 0.4 to 0.6g of seeds per day. Higher doses cause some of the symptoms to get worse.”
          I downloaded and read his latest presentation. It didn’t indicate that he’s doing anything about his immune system, and as one researcher in Dr. Wright’s generation noted in The impact of transgenerational epigenetic inheritance and early life experiences:
          “Every disease is connected to the immune system.”
          Dr. Wright has a lot at stake, but so do all of us. Bad things like diseases of old age happen on their own. If we want good things to happen, we have to make them happen, like one post you recently commented on Gut microbiota therapy.

  2. If I may drop some eaves(eavesdrop) here. My son is on the autism spectrum..a few years back (he’s 18 now) he was eating broccoli sprouts with meals (2x per day) – just a pinch, really.. and one day I supplemented with a broccoli extract capsule just one time. Next day he had a seizure. never had one before and only had one a year after. I am left forever wondering if the combination of sprouts and the extract triggered it. I contacted a researcher and asked it was possible to have too much sulforaphane or whatever chemical in the sprouts/extract and he postulated that one can. On such small quantities..I also took the supplement twice a day. 35mg sulforaphane glucosinolate in each capsule

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