Effect of Proteolysis on Lipase Induced Rancidity in Cheddar Cheese

Cheddar cheese made from milk to which a small amount of commercial lipase has been added will develop a flavor defect known as rancidity (1, 2). This effect is presumably due to lipolysis of butterfat and the consequent liberation of fatty acids, the lower members of which possess an unpleasant odor (3). Rancidity produced in this manner closely resembles the odor of rancid cheese which occurs occasionally but persistently under factory conditions. It has been suggested that milk lipase may be among the factors concerned in the development of rancidity under commercial conditions (4). Since lipases from various sources would be expected to possess many properties in common, the study of lipase induced rancidity is of interest in connection with the rancid cheese problem.