Casein Micelles Partially Hydrolyzed by Chymosin to Modify the Texture of Lowfat Ice Cream

¹ Department of Food Science and Human Nutrition, University of Missouri, Columbia 65211

Lowfat (2%) ice cream was prepared from mixes that were subjected to limited proteolysis with chymosin. The mix was treated with either .64 or .85 IMCU (international milk-clotting units) of chymosin/kg of mix for 15 min at 60°C; the chymosin was derived by fermentation and is commercially available. Chymosin was inactivated by holding the mix at 63.3°C for 30 min. Treated mixes were aged overnight at 4°C, and ice cream (80 to 90% overrun) was produced using conventional techniques. Following chymosin treatment, mix viscosity was significantly increased. Analysis by a trained sensory panel revealed that ice cream made with the chymosin-treated mix had increased hardness, smoothness, cohesiveness, mouthcoating, and mouthdrying characteristics. Treated ice cream was judged by the panel to have a slower rate of melting, decreased adhesiveness, and less graininess than the control. These characteristics were more pronounced for ice cream made with .85 IMCU of chymosin/kg of mix. The difference between treated and untreated ice cream was not as apparent when the finished product was stored for 7 d at –15°C rather than –30°C.

Key Words: ice cream • low fat • chymosin • texture

Submitted on March 27, 1995
Accepted on August 21, 1995