Lipase (triacylglycerol ester hydrolase, EC3.1.1.3) from Candida rugosa was immobilized by adsorption on a commercially available microporous polypropylene support of 200- to 400-mu m particle size. A contact period of 90 min allowed the highest degrees of hydrolysis to be achieved, particularly in the second and third hydrolysis reactions. The optimal hydrolysis conditions were 0.10 kg enzyme per kilogram fat, 50% (w/v) fat, and 40 degrees C for 24 h. The immobilized enzyme can be repeatedly used and hydrolysis degrees of 90% or higher can be achieved. Of the three animal fats studied, edible pork lard consistently yielded the highest degrees of hydrolysis (95%) in the first hydrolysis reaction and inedible beef tallow the lowest (65%). The immobilized enzyme lost ifs activity above 45 degrees C. The support could be easily recovered and reused up to 5 times.