Don’t overcook broccoli

This 2020 US / Korea study set a low bar and jumped over it by finding:

“The abundance of GSL [glucosinolate] hydrolysis products in cooked samples was lower compared to the raw samples.

Regardless of different cooking methods and durations, the total GSL amount in MeJA [methyl jasmonate]-treated broccoli was still higher than in the non-treated broccoli. This suggests that the increased GSL concentration in broccoli samples was solely affected by MeJA treatment, and the effect of MeJA was not affected by cooking methods.

Effect of cooking and 250 µM MeJA treatment on (A) total aliphatic glucosinolates, (B) total indole glucosinolates, and (C) total glucosinolates in ‘Green Magic’ broccoli. * = detected significant different by Student’s T-test (p ≤ 0.05, n = 3) with a significant interaction between MeJA treatment and cooking treatment.”

https://www.mdpi.com/2304-8158/9/6/758/htm “Methyl Jasmonate Treatment of Broccoli Enhanced Glucosinolate Concentration, Which Was Retained after Boiling, Steaming, or Microwaving”


Did it advance science to only replicate mistakes in consumer broccoli cooking methods with:

“The abundance of GSL hydrolysis products in cooked samples was lower compared to the raw samples.”

No.

Did the study design have tests to provide cooking method guidance for:

“To date, methods of delivering cooked broccoli without losing its nutritional benefits are still lacking in the literature, although consuming cooked broccoli is the most common practice for consumers.”

No.

Were there cooking method and temperature recommendations to avoid:

“Cooking also inactivates myrosinase, the enzyme converting GSL into hydrolysis products, and then hinders the formation of hydrolysis products.”

No.

Were there cooking method tests to further enhance either control samples or:

“Exogenous methyl jasmonate (MeJA) treatment was known to increase the levels of neoglucobrassicin and their bioactive hydrolysis products in broccoli.”

No.

Why omit temperature measurements since:

“The major research questions of this study were to evaluate how MeJA application to broccoli plants will affect GSL concentration, myrosinase activity, GSL hydrolysis product amounts..”

Maybe Microwave broccoli to increase sulforaphane levels wasn’t yet published when this study’s design decisions were made. Still, why would a study:

  • Test microwave half power without also testing full power?
  • Select microwaving time as the sole measurement without also measuring temperature?

Table S1 and Figure 3 of the Chinese / USDA study showed a two-minute microwaving time at 50% power wouldn’t be expected to have any sulforaphane content significantly different from uncooked broccoli. Also, temperatures of a five-minute microwaving time at 50% power were guaranteed to completely deactivate myrosinase.

Supplementary material confirmed that this study’s microwaving parameters didn’t show anything of value for how to use your microwave to increase broccoli compound levels. Did the study’s findings provide much more than what not to do?

Poor design decisions created a large gap between what could have been studied and what was studied. Let’s hope there will be better use of resources next time.

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