beanschemistrycooking-time
After soaking dry beans, I place beans on heat, so they boil for couple of hours, and they cook pretty well. But if I add just one cup of cold water (at room temperature) during boiling, temperature of the mixture would drops for some minutes. But then the cooking time of the beans would increase significantly, and it seems they wouldn't cook well ever.
For most of the beans I experienced this process, but I can't figure out why?
You can just soak beans until they are ready to cook. Depending on the bean, it would have variable soak times; but many beans left in water will come to a nice toothsome texture of their own accord (bear in mind they will need to be either sprouted or cooked at the end).
Assuming you have a watertight container for a serving of beans to store them while they soak (I like small pyrex containers for portage), you could also toss them into the skillet or other cooking utensil to boil them. This way you could carry multiple days supply dry, which would make them light and not prone to spoilage but for the quantity soaking.
Frequently, co-ops and health food stores have bulk bins with varieties of dried beans and charts detailing soak times; you could mix your own medley by bagging a few different ones that all have approximately the same soak time.
According to this extensive bean cooking guide from University of Alaska Fairbanks, the secret is to simmer the beans gently. Unfortunately, they have little more to say on the matter.
Kenji Lopez-Alt, in his column on Food Myths at Serious Eats says (emphasis added):
Most of us have been told at some point in our culinary careers that salting beans will cause them to toughen. It's incredible that this little bit of culinary mis-wisdom still lingers, for it couldn't be further from the truth. A simple side-by-side test can prove to you conclusively that salting beans (both the water used to soak them in and the water used to cook them) actually tenderizes the skins.
It's got to do with magnesium and calcium, two ions found in the bean skins that help keep the structure of the beans' skin intact. When you soak the beans in salt water, sodium ions end up replacing some of the magnesium and calcium, effectively softening the skins. Your beans come out creamier, better seasoned, and have a much smaller likelihood of exploding while cooking.
He provides this image of the contrast:
I believe the take away from this is:
The second can easily be achieved by placing the bean pot in a moderate (350 F, 180 C) oven rather than doing it stove top.
Best Answer
If you want to speed up the cooking time and need to add more water, heat it on stovetop or in microwave till steaming, then add. Cook at lower heat just at or below simmer to keep beans more intact and with a cover on to avoid water loss in the first place. NEVER add salt at the beginning of the cooking process, only once desired doneness has been reached. If they just won't get soft (really hard water), add a tablespoon of baking soda to the cooking water, but then they will get soft really fast so watch carefully.