What beans need to be parboiled?

Answer 1

Beans are pre-soaked or pre-boiled to supposedly reduce the chemical that causes gas in human digestion and to reduce the cooking time.

Pre-soaking can reduce cooking time by up to 25%. Soaking in salted water will further reduce the cooking time but you loose water soluble nutrients if you throw away the water.

Pre-boiling does not reduce the cooking time.

Beans are rich in fiber and complex sugars called alpha-galactosides which humans cannot digest. Bacteria in the intestines digest these complex sugars, producing carbon dioxide. The two primary alpha-galactosides in beans are raffinose and stachyose. Cook's Illustrated analyzed how soaking affects stachyose. They found that a long soak led to a 28% reduction in stachyose, and a quick-soak (1 minute boil, 1 hour soak) removed 42.5% of stachyose. Thus, they argue that if you have intestinal discomfort issues from beans then soaking and tossing the soaking liquid will help.

However people still get gas from these beans, due to bad intestinal health and the high fiber content of beans.

Instead of trying to reduce gas by tweaking how you cook your beans, a better strategy seems to be to eat lots of beans and other healthy high fiber foods on a regular basis. The micro-flora in your gut will adapt to a healthier diet so that less gas is produced

So best to soak beans in salted water (can even add stock etc to the soak than after for more flavour).

Always simmer beans to cook do not boil as the outside of the bean can overcook before the inside is cooked. Or you can pressure cook beans to save cooking time.

Salt does not make beans tough.

Acid in the form of wine, vinegar, tomatoes, lemon juice or something similar will make beans tough. So only add acids after cooking.