Mashing banana on Shabbat

Hi,

One may not grind items on Shabbat, but crushing a banana is fine; the banana remains one mass, and is not turned into powder.

However: Because there is a prominent view which does consider this an act of grinding, one should use an abnormal method, such as by using the handle of an implement, if possible.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:74: Tochein 2)

Have a great day,
Mordechai