I had 24-oz. bags of chili mix beans that consist of red kidney beans, navy beans, cranberry beans, and black beans, and which have been stored in our pantry in their original, unopened, plastic bag packages since I purchased them about 10 years ago. I just tried to prepare half (about 12 oz.) of one of the packages by:
Rinsing them thoroughly and repeatedly in a strainer,
Soaking them in plenty of water in a metal pot in my refrigerator for approximately 48 hours,
Draining off the soak water, and rinsing the beans in three to five batches of fresh water,
Boiling for a total of two to four hours, adding water as needed
Letting sit in the hot pot on the stove a while,
Another hour of boiling time
Adding 1/2 tsp of sodium bicarbonate (baking soda) to the pot of boiling beans during the last 10 minutes of that,
Another hour of boiling time, bringing the total number of hours the beans have boiled to four to six hours,
I decided to stop after testing a kidney bean and other smaller beans for softness again, and discovering that, although the bean skins started dissolving off of the beans after I added sodium bicarbonate to the bean and water mixture, the interior of the beans were still hard.
I have learned that very old beans, may never be cooked to softness due to chemical changes that have occurred within the beans's cell structures. However, some people on the Internet advise that very old, dried beans can be cooked to a soft texture if, when you are soaking them prior to cooking them, you add 3/8 to 1/2 tsp of sodium bicarbonate to the soak water. One person also said that, if your beans are very, very old, you may also have to add sodium bicarbonate to the cooking water. I also learned that, if your cooking water is very hard, you will probably have to add sodium bicarbonate in order to be able to cook your beans to softness.
I have decided to throw away these long-boiled beans, as I am now convinced that they must be so old that they will never soften up, something I have read about during my Internet search. However, I am wondering if I can salvage the remaining 1 1/2 bags of the same chili bean mixture by soaking the rinsed beans in water to which I have added sodium bicarbonate. Maybe soaking them in sodium bicarbonate water for a very long time, say 24-28 hours, will work, whereas just boiling them in sodium bicarbonate water wasn't good enough.
Do you think trying this again but soaking the beans in sodium bicarbonate water prior to cooking could work?
I'm also concerned that red kidney beans must boil for a minimum of 10 - 15 minutes, and better yet, for 30 minutes, just to be on the safe side, in order to break down and rid them of the toxins that can make one very gastrointestinally ill. If you have boiled red kidney beans for more than 30 minutes, yet the interiors of the beans are still hard, are they safe to eat, or are the toxin levels in them still too high? In other words, are kidney beans safe to eat after they have boiled for a minimum of 30 minutes, no matter what, or do they still have high levels of toxins as long as the interiors seem uncooked because they are still hard?