Efficacy of multi-stage sous-vide cooking on tenderness of low value beef muscles

The efficacy of thermal activation of residual proteolytic enzymes on shear force and deformation of 72 beef supraspinatus (SS) and rectus femoris (RF) muscles was tested using multi-stage sous-vide cooking (M-SV; 1 h at 39 °C, 1 h at 49 °C, 4 h at 59 °C), single-stage sous-vide cooking (S-SV; 4 h at 59 °C), and waterbath cooking (22 min at 70 °C, to 59 °C). Two storage conditions (1 week at 2 °C; 2 weeks at -1.5 °C) followed, then meat was reheated to and tested at 55 °C. Shear force decreased by 17-21% with S-SV (P < 0.001) and appeared to affect both myofibrillar and collagen components, likely through heat activation of cathepsin B & L and 20S proteasome. A further 5-6% increase was realized with M-SV (P: SS = 0.006, RF = 0.12) affecting primarily the myofibrillar component, likely from calpain-2 activation. The degree of deformation increased with sous-vide cooking in general (P < 0.001). No meaningful effects of post-cooking storage were found (P > 0.05).