Tuesday, May 20, 2014

Kale and Your Health

I have two types of kale in the garden right now. The Winterbor was the first to start flowering and it seems to be about over now. So it was time to cut off the leaves to freeze. I only take the nice spring grown leaves. The leaves that lived over the winter are tough and not worth it. Those I left on the plant. And I lopped of the stem down to those leaves. I don't think I'll get anything more from the plants, but just in case they have another flush of blossoms or leaves I figured I ought to leave them for a week.

I blanched them in boiling water. I really thought about trying to do a low temperature blanch as these are brassicas. So why would I even contemplate this? Well when you blanch you destroy enzymes. Usually this is a good thing. Those enzymes would slowly turn your vegetables to bad tasting mush even in the freezer. This is the reason we blanch produce in the first place. But one of those enzymes destroyed is myrosinase (thioglucoside glucohydrolase) which is a very important one to your health. When the enzyme acts on glucoraphanin it creates sulforaphane. When people tell you that broccoli helps fight cancer they really mean that the sulforaphane helps fight cancer. When they tell you to cut your brassicas and let them sit for a while before cooking this is the reason. You want to make those sulforaphnes before you destroy your myrosinase. BTW a light steaming isn't enough to destroy it so not overcooking your greens is a good way to keep those chemicals around when you cook fresh produce. But if you are preserving and you blanch at low temperatures, the study says 76C, you will retain 80% of the myrosinase.

Well I didn't do that. Can you imagine trying to keep the water from getting over 76C without an automatic thermometer controlling the heat? But luckily someone else came up with a solution. They found that if you put as little as 0.25% of freeze dried diakon radish over the cooked broccoli it is enough. Which is great for commercial processors if they want to help our health. But I don't have freeze dried diakon. Now I might not be a researcher (though I'm obviously a nerd that loves to read), but I know that mustard seed has plenty of myrosinase (though I don't know about commercial prepared mustard as they do have commercial processes to destroy the myrosinase in mustard seed which I'm assuming they do to keep the prepared mustard fresh longer). I know that the myrosinase in mustard seed has the most activity at a pH of around 4.7 so a lemon mustard sauce ought to work well. BTW that pH is different for different myrosinase in the plants. Broccoli's is fairly neutral. Cabbage is alkaline.

This myrosinase-glucoraphanin system is actually a defense mechanism by the plants. The two chemicals are in different but close cells. So when the plant starts getting chewed on sulforaphane (and other chemicals) are formed. Even some humans just hate the taste of the cabbage family. But most of us have evolved to like it. Also it does create a bit of a poison. It can cause hypothyroidism if you eat way way too much of the crucifers for a long time. The one person that it was know to happen to ate about two to three pounds of raw bok choy a day for months. This myrosinase-glucoraphanin system has a couple of mechanisms for harming your production of thyroid hormones. One chemical competes with the uptake of iodine and another interferes with the creation of the thyroid hormones. So everything in moderation. You only need three to five servings a week for the anticancer benefits. And I'm eating brassicas everyday now as they are in season, but I don't eat two pounds a day and I usually cook at least some of them.

My problem of course is that I eat from the garden in the winter so I freeze my brassias to be able to do this. Almost all of my brassicas are frozen from January to mid March. Usually mid March I break down and buy some St. Patrick day cabbages. I do go out to eat and broccoli is a favorite choice. But the reality is I don't get enough of those cancer fighting chemicals over the winter. I really ought to make up a good recipe for a mustard lemon sauce for them. A mustard cheese sauce would be so delicious. And if I buy some fresh horseradish (I'm guessing the prepared stuff has been cooked) I could make a horseradish sauce too. Though I never did find the pH best for the myrosinase in horseradish.

Well I was going to talk about what I did in the garden yesterday too, but I guess my nerd attack took up a lot of space. So I'll write another post later.


  1. I'm still trying to develop my taste for kale...and its toughness. So far, we've enjoyed it raw in chopped salads and cooked down in soups. I can't say I'm a big fan of it sauteed.

  2. This was pretty fascinating. I will have to learn more about the saving and blanching temps over time. We have not saved any greens in the freezer yet and failed at saving green beans b/c they got some kind of icy crystally ick. They were just not so hot at defrost and cooking time. I do love to use frozen and heated spinach and imagine kale, etc would be useful to have in winter. I’m in Seattle area and we have a severe lack of produce avail that’s fresh and local and affordable so it’s a great idea. I found the geekery to be fascinating and wondered if you have a reading source that I could read more about this. I would like to know how to prep my kale for freezing. I have a teeny freezer so won’t be able to save a ton and we save tons of berries so that takes up most of the freezer saved produce space. Maybe this year the berries will get made into jam as they did the first year and we then only have to save a few bags for smoothies, etc. I appreciate your blog and after Granny’s passing, look to yours as her successor for carrying the garden blogger torch!! So keep writing!

    1. I answered you, but you asked about a reading source and I forgot that part. I didn't bookmark anything. I read like a bird flitting here and there. I see something that peaks my interest and move on to that. I tend not to bookmark things. If you want scientific articles with real studies do the search on scholar.google.com. If you pick the right key words like "myrosinase blanch" you will probably find a lot of info.

  3. I get one huge pot of water boiling. I take a bunch of kale that is much smaller than the pot of water. I wash and remove any thick stems. Then toss it into the water. As soon as it hit the water start timing three minutes. Once it is done, remove it immediately and toss it in an ice water bath to cool it down quickly. Then I take a big handful (one serving) of kale and squeeze the water out. I have little plastic containers that I use to freeze it, but I don't leave them there as I don't have enough. I freeze them in the container then pop them out once frozen. The next part depends upon how long I'm storing it. If I preserve it in the spring I go to the trouble of vacuum sealing it. They can store for over a year in a deep freeze that way. If I freeze in the fall I tend to use the small baggies for them. BTW if you don't have a nondefrosting freezer they won't keep as well. A regular freezer will warm up to get rid of the ice which means storage times are shorter. I have a large chest freezer in my basement for storage. I tend to buy most of my meats from the farmers markets in the fall and a lot of my veggies get frozen. So that freezer gets full.

  4. Very cool to know. I can definitely tell you are a chemist at heart! I've never heard to cut your brassicas and then let them sit a bit, but that's good to know and thanks to you I know why. I need to eat more greens. I've never froze my brassicas, so I only eat them in the spring and fall and sometimes in the winter if it is mild.

  5. Go nerd. I love it. Your chemistry roots are showing. My husband is a chemistry professor and I always seek out talks by researchers on cruciferous vegetables when I attend nutrition conferences.