Rheological properties of high-pressure-treated Gouda cheese

The rheological properties of high-pressure-treated (50-400 MPa, 1 h) and u ntreated Gouda cheese were compared. Immediately after pressure release, os cillation measurements gave lower storage and loss moduli from 50 MPa onwar ds. Simultaneously, tan delta was higher, indicating a relatively less soli d-like behaviour of the pressurized samples. Creep measurements showed that samples treated at 400 MPa got less rigid, less solid-like, and more visco elastic; from 50 MPa onwards, the samples had less resistance to flow at lo nger times. Texture profile analysis revealed that samples treated at 225 a nd 400 MPa showed no macroscopical breakage. Relaxation measurements gave a higher level of stress decay at long relaxation times and a higher rate at which the stress relaxes. During further ripening after pressure release, differences between pressure-treated and untreated samples became smaller. At 42 days of ripening, any or only a slight difference could still be obse rved. Dissolution experiments showed that hydrophobic interactions in Gouda cheese were weakened by pressure treatment. This possibly led to structura l changes of the paracasein network causing the rheological property change s. These pressure effects on proteins in Gouda cheese are possibly reversib le as hydrophobic interactions and rheological properties were restored dur ing ripening. (C) 2000 Elsevier Science Ltd. All rights reserved.