Influence of muscle type on rheological properties of porcine myofibrillar protein during heat-induced gelation.

The gelation characteristics of myofibrillar proteins are indicative of meat product texture. Defining the performance of myofibrillar proteins during gelation is beneficial in maintaining quality and developing processed meat products and processes. This study investigates the impact of pH on viscoelastic properties of porcine myofibrillar proteins prepared from different muscles (semimembranosus (SM), longissimus dorsi (LD) and psoas major (PM)) during heat-induced gelation. Dynamic rheological properties were measured while heating at 1°C/min from 20 to 85°C, followed by a holding phase at 85°C for 3min and a cooling phase from 85 to 5°C at a rate of 5°C/min. Storage modulus (G', the elastic response of the gelling material) increased as gel formation occurred, but decreased after reaching the temperature of myosin denaturation (52°C) until approximately 60°C when the gel strength increased again. This resulted in a peak and depression in the thermogram. Following 60°C, the treatments maintained observed trends in gel strength, showing SM myofibrils produced the strongest gels. Myofibrillar protein from SM and PM formed stronger gels at pH 6.0 than at pH 6.5. Differences may be attributed to subtle variations in their protein profile related to muscle type or postmortem metabolism. Significant correlations were determined between G' at 57, 72, 85 and 5°C, indicating that changes affecting gel strength took effect prior to 57°C. Muscle type was found to influence water-holding capacity to a greater degree than pH.