I've heard that you never add baking soda to beans at any stage of the
cooking, even the soaking stage. It will harden the skin of the bean.
I could be wrong, of course, but that's what I've always been told.
For those who are not allergic to any form of MSG, kombu brings out
the flavor of the bean and perhaps cuts back on some of the less
pleasant effects of eating beans.
Kombu is a source of glutamate, that's why they make beans taste
better. If I'm out of kombu in my kitchen, I just don't cook
beans...but I'm never out of kombu.
Personally...I break the "rules" and pressure cook many of the beans I
cook. I know...never cook beans in a pressure cooker because they
foam. One spritz of non-stick spray added to the water negates that.
No soaking, no nuttin', and the beans are ready in about an hour from
start to finish.
If anyone would like to try using the pressure cooker, there is one
downside: they just don't get cooked all the way through. So about 30
minutes into cooking, release the pressure, open the cooker and stir,
stir, stir. That should help your beans cook all the way through
after you put the top back on and bring it back to cooking "speed."
If you still experience some underdone beans, cook them for a bit
longer. There is no such thing as an overdone bean.