500-600g frozen prechopped Kale. It contains a small amount of liquid (or rather ice). I’d guess maybe 5%-10% of the weight is the liquid. I am not sure if they count the water. I would buy the thing that says either 600g on the packaging, or 1kg, and then use half.
Also, I always drink the cooking liquid. I am not sure that is required, but it has a pretty strong kale taste so I’d guess there is probably at least some more kale goodness in there.
Chopping it and then waiting at least 40 minutes before cooking it or mixing some mustard powder to cooked kale helps produce the anti-cancer nutrient, sulforaphane.
For other dark leafy greens, boiling is not best nutritionally, although if you’re drinking the water, you’re probably well covered.
“The main purpose of cooking vegetables is to make them more edible, palatable, and digestible.” The downside, though, is that “cooking may adversely affect the levels of nutrients, especially the heat-sensitive and water soluble ones.” But even if you boil greens for 10 minutes, the drop in antioxidant capacity, for example, which is a rough proxy for phytonutrient retention, isn’t that much. Yes, there’s a significant drop in each case—a 15 to 20 percent drop—but most of the antioxidant power is retained, even if you boiled lettuce for 10 minutes. The single nutrient that drops the most is probably vitamin C, but as you can see, collards start out so vitamin C-packed that even collard greens boiled for 10 minutes have twice as much vitamin C compared to even raw broccoli.
You can see the vitamin C in spinach really takes a hit. Even just blanching for five minutes can cut vitamin C levels more than half, with more than 90 percent dissolving away into the water after 15 minutes, though most of the beta carotene, which is fat soluble, tends to stay in the leaves. But just keeping it in a regular plastic bag, like you get in the produce aisle, can protect it. The refrigeration is important, though. Even in a bag, a hot day can wipe out nearly 50 percent. Not as bad as drying, though, which can wipe out up to 90 percent of the vitamin C, suggesting that something like kale chips may pale in comparison to fresh—though vitamin C is particularly sensitive. Other nutrients, like beta carotene, are less affected across the board.
What does cooking do to it? Fresh is best, but steaming’s not bad, with microwaving coming in second, and then stir-frying and boiling at the bottom of the barrel.
on
Cooking by microwaving and steaming preserves the nutrition more than boiling, here measured in watercress. A little steaming or microwaving hardly has any effect compared to raw, though boiling even two minutes may cut antioxidant levels nearly in half. Watercress is a cruciferous vegetable, though—a cabbage- and broccoli-family vegetable—so it’s prized for its glucosinolate content, which turns into that magical cabbage compound sulforaphane.
Sorry, this comment is not well editing for length. I find myself wanting to explore these interactions with a graph model, taking inspiration from wikidata and software mindmaps, beyond just tree relationships.
500-600g frozen prechopped Kale. It contains a small amount of liquid (or rather ice). I’d guess maybe 5%-10% of the weight is the liquid. I am not sure if they count the water. I would buy the thing that says either 600g on the packaging, or 1kg, and then use half.
Also, I always drink the cooking liquid. I am not sure that is required, but it has a pretty strong kale taste so I’d guess there is probably at least some more kale goodness in there.
It looks like kale has been absolved of high oxalate concerns, in contrast to spinach.
You might benefit from mixing in ground mustard seed (or fresh / thawed chopped cruciferous vegetables), per https://nutritionfacts.org/topics/kale/.
For other dark leafy greens, boiling is not best nutritionally, although if you’re drinking the water, you’re probably well covered.
on
Explaining sulforaphane production with respect to cooking techniques, pre-nutrient plus enzyme reaction time between mechanical breakdown and cooking.
Sorry, this comment is not well editing for length. I find myself wanting to explore these interactions with a graph model, taking inspiration from wikidata and software mindmaps, beyond just tree relationships.