Water-holding capacity and gel strength of rennet curd as affected by high-pressure treatment of milk

The effect of high pressure (HP) treatment on two gel characteristics, wate r-holding capacity (WHC) and gel-strength (GS), of rennet curd was evaluate d as a function of pressure (200-400 MPa), temperature (3-21 degrees) and h olding time (10-110min) using a response surface methodology. A central com posite design was used to investigate the effect of process variables and a second order multiple response model was used to relate the pressure, temp erature and holding time to WHC and GS. In general, with a decrease in pres sure level, temperature and holding time, there was a decrease in water-hol ding capacity and an increase in the gel-strength of the rennet curds. The conditions of minimum of WHC (40%) were: pressure, 280 MPa; temperature, 9 degrees C, and holding time, 42 min which also resulted in a high gel stren gth of 0.47N slightly below the maximum of 0.52N. (C) 2000 Elsevier Science Ltd. All rights reserved.