Buffaloberries already contain saponins...
http://www.aihd.ku.edu/foods/buffaloberry.html The berries were also commonly eaten raw, but only after the first frost has naturally sweetened them, and even then in moderation (Moerman 1998: 528-529). Eating too many buffaloberries in any form causes diarrhea (Marles et al. 2000: 169) and may be fatal. The substance that causes the buffaloberry to become frothy when beaten is called saponin, which is utilized commercially as a foam producer and is thought to cause the fruits bitter flavor (Angier [2008] 1974: 30).