From the Master Gardener list:
Cooks Illustrated just had an article about cooking dried beans where they soaked the beans overnight in salt water instead of just plain water. Even though adding salt too early to the cooking process is reputed to make bean skins tough, soaking in salt water actually made the beans more tender. Their science sidebar explains that the calcium and magnesium ions in the bean skins are being replaced with the sodium ions, which are weaker and allow more water to penetrate. Furthermore, the technique also offsets the effect of hard water with high calcium and magnesium content, which many of us have. I just tried it and it really seemed to work, although I didn't do a side-by-side testing with the same beans in salted & unsalted water (maybe I will next time!). The beans did not seem to end up tasting salty, btw.
The proportions are 1 lb of beans, 4 quarts of water, and 3 tbsp of table salt (I used 4 tbsp kosher salt). Soak for at least 8 hrs and up to 24 hrs. For a quick soak, bring 2 quarts of water and 3 tbsp of salt to a boil, pour over the beans, and let them soak 1 hr. Drain & rinse the beans and proceed as usual.
And a response:
After listening to Narsi David, Bay Area Chef Expert on KCBS, he always suggest after bringing the water to a boil, keep the pot covered for an hour and pour all that initial water OUT. Apparently most of that water contains a complex sugar that when ingested by us is what causes much of the gas that beans tend to produce.
By pouring out that that initial water and rising the beans will help remove maybe 90 to 95% of the gas producing sugars. Then just finish cooking them in whatever you like.
Beans are a great source of proteins, iron and fibers. Bon Appetit!