Everyone who has ever tried fresh pineapple knows that if you eat too much, your lips and tongue hurt for a while. This is because the pineapple contains an enzyme called bromelain. This enzyme literally "erodes" the tongue.
Bromelain has the property of destroying protein. On the one hand, it promotes digestion, helping the body absorb protein foods. Also, you can add fresh pineapple juice to the steak, and it quickly softens the meat.
On the other hand because of its activity, you cannot eat too many pineapples, because under the influence of bromelain your tongue will "be digested" literally by this enzyme. However, the cells of the tongue recover very quickly, so you do not face to eat your own tongue with pineapples.