Thermal stability of connective tissue from porcine muscles

Connective tissue of three porcine muscles (M. infraspinatus, IS; M. longissimus dorsi, LD; M. semimembranosus, SM) from 27 animals [populations A (n = 13, reared in Ireland) and B (n = 14, reared in Finland)] was studied by measuring the collagen content, collagen solubility and thermal shrinkage temperature of the connective tissue. Colour and pH were also determined. Collagen solubility was highest in IS (p < 0.05) and lowest in SM (p < 0.05) although no difference between LD and SM was found in population B. The onset and peak temperatures of thermal shrinkage (To and Tp) were highest in IS (p < 0.05). The lowest To and Tp were found in SM from population B whereas no differences were seen between LD and SM muscles in population A. It was concluded that the thermal stability of the connective tissue in the three porcine muscles differ. IS, as a dark muscle has high thermal shrinkage temperatures and high collagen solubilities in comparison to the lighter LD and SM muscles which have lower thermal shrinkage temperatures and collagen solubilities. Collagen contents were highest in IS and lowest in LD.