Baking soda is greatly under appreciated ingredients in too many kitchens. Most chefs know it only as something you add to cakes and quick breads, and maybe a box you leave open in the refrig to absorb smells. To learn more about baking soda, we need to get back to a little basic chemistry. Sodium bicarbonate, aka baking soda, is a good buffer that keeps the pH around 8, mildly alkaline.
Depending on where you live, the pH of tap water may vary considerably, and the ingredients we add to foods may also modify the pH. For example, canned tomatoes often have citric acid added to keep the tomatoes flavor fresh. The problem is that the way many foods cook depends strongly on the pH. For example, beans just won’t soften no matter how long you cook them in an acidic solution. Adding 1/2 tsp of baking soda per quart of water when you cook beans speeds up the process and makes it much more reproducible. Similarly, adding a similar amount of baking soda to the water when you blanch vegetables greens them up and speeds the process.