Chilled storage of high pressure and heat-induced gels of blue whithing (Micromesistius poutassou) muscle

 Microbiological, rheological and chemical characteristics were examined in gels made from the muscle of blue whiting (Micromesistius poutassou) and subjected to three different combinations of pressure, temperature and time: 200 MPa at 3  °C for 10 min (lot L), 375 MPa at 38  °C for 20 min (lot H) and atmospheric pressure at 37  °C for 30 min followed by 90  °C for 50 min (lot T), and kept in chilled storage for 20 days. The microorganism content dropped at the outset as pressurizing took effect, the highest microbial content being found in lot L; however as the effect was not lethal, the total load increased over the following days. Microbial load was significantly lower in lot T. During chilled storage, the values of breaking deformation, breaking force and cohesiveness of lot L were higher than those of the other lots, although they did decrease with storage. The heat-induced gel was much harder, had greater water-holding capacity and was considerably more stable than the high-pressure-induced gels. The lightness value was higher in lot H than in the other two lots. In general, changes in protein solubility tended towards the cleavage of strong bonds as a result of microbial action. The electrophoretic profiles evolved differently in each of the lots over the chilled storage period. However, all of them exhibited large numbers of bands of lower molecular mass which could have been the result of degradation. This was particularly evident in lot H. The heat-induced gels exhibited a highly porous ultrastructure, quite different from the high-pressure-induced gels; these had a more compact matrix which expanded as storage progressed. Received: 26 May 1997