Should I rinse canned beans before using them?
Certainly, if I were making a salad with canned beans, I would thoroughly rinse them first. But if I'm making soup or chili with canned black beans or kidney beans, should I drain and rinse them first? Goya brand beans have recipes on the side of the can that call for undrained beans.
On the one hand, I've heard claims that using the liquid in the can will increase gassiness, and that in some brands it can contain a lot of sodium. But I've also heard that it contains lots of soluble fiber that is lost if drained. Is there merit to either of these claims? Are there other nutrients that get lost if I drain and rinse? I always feel bad throwing out anything edible.
I finally found what I'm looking for, from the University of Michigan - some actual data on the subject!
They say that rinsing canned beans can reduce the amount of sodium by half, and also reduces the amount of complex sugars which humans can't digest (but the bacteria in our intestines can, with uncomfortable results!)
It appears that draining the fluid is likely to improve the flavor and texture of the resulting food by concentrating the flavor of the beans -- unless you're following a soup recipe that specifically suggests retaining the liquid to thicken the soup.
I still haven't found any information about what healthy nutrients might be lost by rinsing the beans, but the general consensus seems to be that it rinsing will do more good than harm in almost all cases.
If I need to thicken my soup, I will sometimes reserve a few tablespoons of the liquid. I also reserve the fluid from one can (of two) when making Hummus from Garbanzo beans. In general though, at least drain them; I think rinsing is optional.