Ever wondered why they are slashing the skin of these papaya fruits? Is this white liquid some kind of vegan milk? You see, that milky sap contains a proteolytic enzyme called papain. This latex is extracted only from immature fruits because ripe ones don't have it. The fruit should be tapped in the morning, during a period of high humidity, to ensure a high latex yield.
Papain can be potentially dangerous. As an enzyme that dissolves protein, so direct contact with the skin can cause burning or allergic reactions. Once processed, papain has a variety of uses, including the preparation of vaccines, de-worming cattle, tanning leather, and use in facial masks in cosmetics.