“Does Pressure Cooking
Preserve Nutrients?” In a review of more than a
hundred articles about the effects of cooking on vegetables,
they tried to find the sweet spot. On one hand, heat can
destroy certain nutrients; on the other hand, by
softening the tissues they can become more bioavailable. Researchers settled upon steaming
as the best cooking method to preserve the most nutrition. You’re not dunking
it in water or oil where the nutrients can leach out, and you’re not reaching excessive
dry heat temperatures. But they acknowledge that of
all the common cooking methods, we know the least about
pressure cooking. There’s all these fancy new electric
pressure cookers on the market, including the Instant Pot,
with more five-star ratings than even How Not to Die—I’m jealous! These pressure cookers are
great for cooking dried beans with just a touch of a button. But what happens to the nutrition? Here’s the antioxidant content
of presoaked black beans boiled for an hour normally. Compare that to pressure
cooking for 15 minutes…. Even more. In fact, six times more! Wow! Here I was pressure cooking
just because I liked the texture better (the canned ones can be a bit mushy), and I was spending lots of
money on cases of canned beans, whereas dried beans are
just so dirt cheap. So wait, cheaper,
tastier, and healthier? That’s quite a combo. OK, but what about
pressure-cooking vegetables? Vitamin C is one of the
more heat-sensitive nutrients. Sauté spinach or amaranth
leaves in a pan for 30 minutes, and about 95 percent of
the vitamin C is destroyed; whereas 10 minutes
in a pressure cooker wiped out only about 90 percent. But who pressure cooks
spinach for 10 minutes? And sautéing for
a half an hour? And even then, not
much effects on beta carotene levels either way. Vitamin C is but one
of many antioxidants. What about the effects of pressure
cooking on overall antioxidant capacity? Here’s the cooking methods
they compared. So, for the carrots, for
example, 12 minutes of boiling, compared to 5 minutes
of pressure cooking, compared to 6 minutes
of microwaving. Here’s what they found. Cooking carrots increased
their antioxidant potential. In fact, pressure cooking nearly
doubled their antioxidant value, whereas peas took a hit no
matter how they were cooked. I’m particularly
interested in the greens. The chard wasn’t affected
much across the board, but microwaving beat
out pressure cooking and boiling for the spinach. Note that pressure cooking
beat out the boiling too, though, and pressure cooking is boiling (just at a shorter time
at a higher temperature.) But the time appeared to
trump the temperature. Significantly less nutrient
loss pressure cooking spinach for three and a half
minutes compared to boiling for eight. Same for those magical cancer-
fighting glucosinolate compounds in cruciferous greens—
the healthiest greens like kale, collards,
and turnip greens. Here’s where levels
started out raw, with three-quarters
wiped out by boiling, but less than half
with pressure-cooking. Now both got beat by steaming,
but that’s because you weren’t dunking the greens in water,
which can leach out the nutrients. But even though the
pressure-cooked greens were immersed just as
much as the boiled greens, only half the nutrient losses,
presumably because it was only half the time—
7 minutes pressure cooked compared to 15 minutes boiled. OK, so here’s my idea. This was after 10 minutes of steaming. What if you cut down that
time by pressure steaming, like put a layer of
water down at the bottom of an electric pressure cooker,
drop in a metal steaming basket on top, and then put the greens
in and steam under pressure? That’s how I cook the
greens I eat every day. I’ve always loved collards
in like southern cooking, or Ethiopian cuisine, and I
found I could get that same melt-in-your-mouth texture just steaming under pressure
for zero minutes. What you do is set it for zero,
so it shuts off as soon as it reaches the cooking pressure, and then
quick release valve it immediately to release the steam. The greens turn out perfect— bright emerald green,
cooked tender. Give it a try, and let
me know what you think.