For those of you trying your own refried beans at home, there is a fart-proof herb called epazote (you can get it through Cool Chile Co.) and although it adds nothing to the taste of the beans it diminishes, shall we say ... the flatulent factor involved.
If you want to eat lots of Mexican food, and have lots of presentations to make the next day, and you do not want to fart the next day, use epazote. (This works for refried beans with pintos and black beans, and also black beans de la olla).
Totally fart-proof.
Nuff said, Stu the Southern Californian.