I have just stumbled upon various recipes (in German, example) that instruct to blanch kale and immediately afterwards cook it at a high temperature for at least an hour, starting with an interval of boiling.

My understanding is that the only purpose for blanching vegetables is to deactivate enzymes and germs. This makes sense before storing or using the vegetables without further comparable heating. However in the recipes in question, this would happen during the subsequent cooking anyway.

Is there any point to this step or is it just a waste of time and resources?


2 Answers 2


Some vegetables can have a certain amount of bitter components naturally occurring in the plants. Cooks and gardeners have found ways to mitigate what is sometimes perceived as unpleasant.

  • For kale, harvesting after the first frost is common when higher sugar content counteracts the perceived bitterness (not the absolute content). Adding sugar or sweet fruit to the dish is a traditional method to achieve the same.
  • Breeding has reduced bitterness, but of course in stores you usually don’t get detailed information on what cultivars are on offer.
  • And finally blanching leaches the bitter components into the water, which then can be poured off.

So no, the blanching step is not futile for kale, even if a lengthy cooking phase follows.

  • Interesting. I've never done anything with kale other than de-vein the heavier parts, then steam it a few mins, same as cabbage.
    – Tetsujin
    Feb 12, 2022 at 15:28
  • A trick used (or used to be used) in the Netherlands is to freeze kale before cooking, in the old days by not harvesting till after the first frost, now by putting it in the freezer for a night or longer. That will get the kale convert some of its taste into sweeter versions.
    – Willeke
    Feb 12, 2022 at 17:59

I would not blanch kale for a recipe like that.

Generally, one blanches kale for recipes where the kale is going to be cooked for a very short time, like pasta dishes. In this case, you need the blanching in order to prevent bitter or raw flavors because the kale is not cooked enough.

In slow-cooked recipes, however, this step is wholly unnecessary; most do not include blanching. You don't need the blanching to ensure full cooking, since the kale will cook for an hour, and you don't need it to preserve color because nothing will preserve color through cooking it that long.

As to why the recipe recommends it, I can think of two possible reasons:

  1. Some cooks, particularly in restaurants, prefer to follow simple rules for vegetable prep. Thus "first step is always to blanch the kale", regardless of how it's going to be cooked later.
  2. It's possible that kale was more bitter in the past, and needed to be blanched even if being slow-cooked. Brussels sprouts have been engineered to be less bitter, kale may have been too. So blanching first might have been good advice in 1970.

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