Recently, we purified two acid proteinases (MpiAP1 and MpiAP2) from Monascus pilosus. In this study, we examine the potential application of these enzymes in the production of low-antigen whey protein. Hydrolysates of whey protein concentrate (WPC) were prepared enzymatically using MpiAP1, MpiAP2, pepsin and tiypsin, both singly, and in combination. The electrophoretic analyses of WPC degradation showed that casein is the component most favored by all enzymes. The a-lactalbumin was completely digested by fungal acid proteinases but not by gastrointestinal proteinases, and beta-lactoglobulin was effectively digested by trypsin only. The complete digestion of all WPC components was accomplished with the addition of trypsin to partially hydrolyzed WPC treated with Monascus acid proteinases. The lowest antigenicity was observed in the WPC hydrolysates treated with MpiAP1/MpiAP2 and trypsin by competitive ELISA. Our results suggest that Monascus acid proteinases can be effectively used to make hypoallergenic bovine milk whey protein hydrolysates. (C) 2010 Elsevier Ltd. All rights reserved.