Q. This is a question regarding the post-meal results: I know that many vegetables and legumes cause gas in digestion, and I would like to know if there is any particular method of cooking certain things (especially mushrooms) in order to make them less gassy later on.
A. The issue to which you so delicately refer is caused by the presence in certain foods of carbohydrates that the body doesn’t digest or absorb. These sugars are consumed by bacteria in the tail-end of the digestive tract and the by-product speaks for itself. Beans are the most notorious culprits, but cabbage (especially cooked), onions, radishes and even potatoes, apples, peanuts, raisins and bananas can present a challenge. Some people manage these sugars (oligosaccharides) better than others.
Of those foods, cookbooks generally only speak of ways to mitigate the problem with beans (soak them for an extended period in cold water and change the water before cooking). The other foods are less problematic, and in many cases, no one has come up with a great solution anyway. As you can note with cabbage, cooking heightens the problem, rather than lessening it. There are tablets on the market of a particular enzyme that claim to provide relief, but some scientists do not believe they are effective.
In looking through half-a-dozen serious mushroom cookbooks, we have not come across any reference to "post-meal results" or how to mitigate them, other than a brief statement in one book that thoroughly cooking wild mushrooms makes them more digestible. In the old school, mushrooms were cooked for a long time over medium heat. The more recent trend to cook them for only a couple of minutes over high heat (and avoid complete mushiness) could leave them underdone and increase their retention of the offending carbohydrates.