The enzyme from papaya used in chemical exfoliants is papain.
Papain is a cysteine protease, meaning it breaks down proteins by cutting peptide bonds. It occurs naturally in papaya, especially in the milky latex of unripe fruit, and is also found in mountain papaya. In skincare, its protein-digesting activity is used in some enzyme exfoliants to loosen dead cells on the skin’s surface.
Papain is not an acid exfoliant such as glycolic or salicylic acid. It is an enzymatic exfoliant, and cosmetic formulas may combine it with other ingredients. Its effect depends on concentration, formulation, contact time, and skin sensitivity. Products containing papain can irritate some users, particularly those with allergies to papaya or latex-related sensitivities.
The enzyme has many uses beyond cosmetics. Papain is added to meat tenderizers because it breaks down tough muscle proteins, and it has been used in food, textile, leather, detergent, dental, and pharmaceutical applications. Scientists also use it to cleave antibodies into smaller fragments for laboratory and medical research. Bromelain, the enzyme associated with pineapple, is a common mix-up, but it is not the papaya enzyme.