Cooking methods vs nutritional value

Steaming isn't much better than boiling. Pressure cooking claims to "retain" nutrients but it's mostly about time vs loss there. All of those methods lose nutrients from temperature, water solubility and time.

But in a modern diet in any first or second world nation, nutrient loss is not worth worrying about. Enough variety is consumed it's not an issue.

I have often wondered about this.  I understand that there is more nutritional value to eating raw broccoli than cooked broccoli because the cooking process destroys some of the nutrients.  Plus you may be adding ingredients that add calories and counteract the beneficial nutrients of the vegetable like oil, butter, cheese, cream, breadcrumbs, etc.  However, it is certainly a lot easier to eat steamed broccoli vs. raw broccoli therefore I eat more of it.

I'm a big fan of vegetable stews.  Just last night I made a green bean stew with potatoes, tomatoes, onion, and lots of garlic swimming in a sea of olive oil.  It was greek peasant food at its best, lots of fresh bread to sop up the sauce.  I often think that a dish like this while seemingly healthy because it's all veggies may not be as good for me as I used to think when I was younger.  The beans are cooked down until soft.  There's lots of olive oil in there.  Is it really a vegetable dish if it's high in calories, has been cooked for an hour, and requires lots of bread?

It really depends on what you mean by "nutrition," KK.

Conventional wisdome would have you correct. We take it as a matter of course that the cooking process destroys nutrients. But this is not supported by the facts.

For instance, let's look at broccoli, and compare 100 grams of raw vs 100 grams boiled, with salt.

The proximates are pretty much a wash, with protein being the only significant difference. Here the raw comes in at 44 grams higher. It's also slightly higher in ash and sugars, but lower in energy (not significantly so), fibre, and carbohydrates.

Minerals are all over the lot. Raw broccoli is higher in calcium, potassium, maganese and selenium, but lower in iron, phosphorus, zinc and copper. Sodium is the big difference, with the cooked coming in at 229 mg higher---but remember, we added salt to it.

The big surprise comes with vitamins. We've always thought that heat destorys them, right? Well, maybe. Raw broccoli is slightly higher in niacin, but lower in vitamin B-6. It is, oddly enough, significantly lower in beta carotene, and very significantly lower (to the tune of 925 IU) in Vitamin A.

The lesson to be learned from this: never assume anything about the nutritional values of food. If it's important, check with a reliable source.

My figures, btw, come from the USDA Composition of Foods database.

I understand that cooking makes certain nutrients more useable to us, more easily assimilated.  Carrots are famous for being more nutritious cooked. 

I think also you have to consider that heat destroys vitamin C but that doesn;t mean it destroys other vitamins.  Maybe that thing about cooking vegetables making them lose their nutrients comes from that.    It seems to enhance oil-based vitamins like A and E (carrots, A).  I believe broccoli is high in all of these.  But it;s enough to have some uncooked fruit every day and you get your vitamin C anyway. 

Personally, i never liked steamed vegetables - they always cooked unevenly for me - broccoli coming out hard as wood in some points and cooked to a brown mush in other points.  I prefer a large pot of boiling water, cooks them all evenly and for a much shorter time.  If you put them in cold water, you're surely going to leach out more nutrients. 

Others tell me that steaming works fine.  Maybe they make a lot less vegetables or have a giant steamer.  For a family of 3 or 4 you need quite a bit of broccoli, and i'd like to see the steamer that can handle it. 

and i'd like to see the steamer that can handle it. 

Comeonna my house. My 12" bamboo steamer has four trays. Plenty of room for just about anything.

At home, those silicone strainers that sit on the bottom of the pan work real well for steaming.  Less water to boil, more efficient, faster than boiling, holds a couple of portions unless you really love broccoli.  Cut the stems down to a size they will be done when the tops are done.  Cooking until just done is hopefully the key to retaining the most nutrients, whether steamed, boiled or in the pressure cooker.  

Quote:

Originally Posted by Seabreeze 

Thanks everyone for the input.  I've been using the USDA tables, but was curious if anyone knew of comparisons between the various cooking methods.  USDA doesn't list pressure cooked as one of the prep options.  The closest is boiling.  Boiling leaches some nutrients (vitamins/minerals) and pressure cooking with its high temp but short duration affects temp sensitive nutrients.  I was hoping someone already did the legwork on the specifics so I would't have to.  Getting lazy in my old age

I'm interested in retaining as much nutrients as possible, you almost have to be a scientist to weed through the info.  I've seen conflicting studies about the B and C vitamins and steaming vs boiling.  Broccoli has so much vitamin C, I think as long as you dont cremate it, its good.  Not sure about B.  Its the phytonutrients that I want to keep in broccoli, one study found boiled for 5 minutes lost 15% of glucosinolate's and 10 minutes destroyed 40%.   Very little loss of glucosinolates when steamed even for up to 20 minutes, thats how i read it.  Same researchers studied something called tenderstem broccoli and found it a lot more nutrient rich than any other variety, not sure if that is even available in the USA.  

ah, yes, the big bamboo steamers - had one once but had to get rid of it - i never had very good luck with even cooking with them, and in any case they occupy way too much precious space (they don't stack one inside the other, so it's wide AND high!