An Instron Universal Testing machin

An Instron Universal Testing machine (Model 4442, Instron Corp., Canton, MA) was used. Whole cooked burger (100 mm diameter, 10–12 mm height) cooled at room temperature were placed on the stationary plate and compressed with a 20 mm in diameter descending plastic punch to determine mechanical relaxation force (Bourne, 2002). Burgers were compressed up to 15% of deformation, the highest that does not produce burger failure. At this preset deformation level, the crosshead was stopped. The relaxation force was recorded along 10 min and the final value (residual relaxation force named F10) was evaluated. Determinations were performed in ten burgers in replicates of three