Papain (EC 3.4.22.2)

Papain (EC 3.4.22.2) is a protease derived from the latex portion of the papaya plant ( Carica papaya ), and is gathered by scoring the surface of the mature, unripe fruit, after which the latex is collected and dried (Schwimmer, 1981) . Drying can occur by one of several methods: sun, oven, or spray drying; end products having the highest activity are obtained by spray drying. 

Papain has broad-spectrum enzyme activity over a wide pH and temperature range , and it cleaves at basic amino acids or those having large hydrophobic side chains. Resulting peptides having terminal hydrophobic amino acids can result in a product with a bitter aftertaste. For this reason, papain is usually combined with other enzymes in the production of flavorings. 

Because papain is a thiol protease, oxidation of its cysteine residue under certain conditions can reduce the enzyme’s activity or potency. For this reason papain preparations often contain reducing agents such as sodium metabisulfite. Papain is economically available commercially in both liquid and powder forms. It has the longest history of use in meat systems and is the basis for some of the popular tenderizing sprinkle-on products that can be purchased by home consumers (Enzyme Development Corporation, 1999) .