Gels made from the flesh of mackerel (Scomber scombrus) and fortified with rosemary extract and omega-3 unsaturated fatty acids were studied in connection with high pressure/thermal treatments. Elasticity and breaking deformation were significantly higher in pressure-induced gels (300 MPa, 25°C, 15 min), while hardness was considerably lower. For gels without ingredients the fraction solubilised with 8 M urea and 2% β-mercaptoethanol was larger in the pressurised samples, indicating more covalent bonding in heat-induced gels which could not be disrupted by the solubilising agent. Scanning electron microscopy showed that pressure-induced gels generally presented a structure more compacted than heat-induced gels. The high pressure activated lipid oxidation, the antioxidant effect of rosemary being evident in all samples

This research was supported by the Spanish Comisión Interministerial de Ciencia y Tecnología under projects ALI 99-1105 and ALI AGL2000-1497.

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