Why do some put baking soda in black bean soup?

There are two main reasons why you might see recipes suggesting baking soda:

1. To neutralize acidity: In some cases, people add baking soda to neutralize the acidity of tomatoes or other acidic ingredients in a soup. This is sometimes done to prevent the soup from becoming too tart or to enhance the flavor of the beans. However, this is not common practice for black bean soup.

2. To soften beans: Baking soda can be used to soften tough dried beans by breaking down the pectin in the beans. However, most black bean soups use canned beans, which are already softened and don't require this treatment.

Important note: Adding baking soda to soups can affect the flavor and texture. It can create a soapy or metallic taste and can make the soup overly soft.

If you're making black bean soup, you can skip the baking soda altogether.