Some fruit that contain protease enzymes include pineapple, papaya, kiwi and figs. Proteases belong to a class of enzymes that break down protein. These enzymes are found throughout the plant and animal kingdom. In animals, they primarily function to help digest meat and other protein sources.
At first glance, it may seem curious that many tropical fruits contain digestive enzymes, but in plants, protease enzymes regulate development and photosynthesis. Even in animals, protease enzymes may be found performing a variety of functions beyond digesting particular foods. For example, protease in blood aids in proper blood clotting. Many protease enzymes regulate hormone function.
Different kinds of fruit have different types of protease. These enzymes have found many human applications. Figs contain ficin, which is used as a dewormer, and Kiwi contain actinidin, which is used to treat constipation.
Particularly notable is bromelain, the protease found in pineapples. Because of bromelain's ability to break down meat, pineapple juice is used as a meat tenderizer. Isolated bromelain is also sold in stores for just this purpose. In addition, bromelain is also used in Europe to help patients recover from surgery and athletic injuries. The evidence that bromelain helps ease inflammation is inconsistent, but it is also sometimes used to treat arthritis.
Papaya's protease, papain, is widely used in industry. It clarifies beer, clots milk and tenderizes meat and is also used in some medical applications, such as treating jellyfish stings and promoting recovery from wounds. Like other protease enzymes, including bromelain, it is also used for digestion.