Rennet coagulation properties of raw, pasteurised and high pressure-treated goat milk

In this work, rennet coagulation properties (rennet clotting time, rennet curd aggregation and curd firmness) of raw (RA), pasteurised (PA, 72°C, 15 s) and high pressure-treated (PR, 500 MPa, 15 min at room temperature) milk were assessed on line (in the cheese vat) using a non destructive objective method (Gelograph®-NT).The technological treatments caused an increase (p<0.05) on the rennet clotting time (PR>PA) with respect to RA milk. Pasteurisation did not affect rennet curd aggregation and firmness suggesting that PA milk has the same cross-linking capacity as RA milk. However, both aggregation rate and firmness were higher in PR milks than in RA or PA milks. These results provide interesting information for improving the cheese making capacity of goat milk as high pressure treatment, although the rennet clotting time increased, considerably improved the aggregation rate and curd firmness.