Biomechanical compression studies at different temperatures were conducted tocorrelate the biomechanical response of raw bovine Longissimus dorsi muscles varyingin USDA Quality Grade with overall sensory tenderness scores. Phase 1 assessed thebiomechanical properties of raw 2.54 cm3 samples obtained with a Texture Analyzerfitted with a 10 cm diameter platen which applied a constant strain of 3% for fourminutes. Muscle specimens were arranged with fibers in parallel and perpendicularorientations to the applied force and tested at 0, 2, 4, 6, 8 and 10????C. Initial stiffness,final stiffness and energy dissipated of raw steak cubes with fiber orientation in paralleland perpendicular fiber orientations were calculated using the models and technique ofSpadaro (1996) and correlated to overall sensory tenderness scores for each compressiontemperature. All compression values had higher correlation coefficients with overallsensory tenderness than did Warner-Bratzler Shear Force (WBSF). Of the predictionequations developed, it was concluded that samples compressed perpendicularly at 2????Cwere better predictors of overall sensory tenderness (R2 = 0.77) than WBSF (R2 = 0.11). Phase 2 assessed the biomechanical properties of raw steaks (2.54 cm thick) using a 2mm diameter stainless steel probe in lieu of the platen and compressing samples 0.635cm for 0.25 sec at -6.6, 4.4 or 10????C. Initial stiffness (ISTFPR), final stiffness (FSTFPR)and energy dissipated (EDPR) of raw intact steaks were calculated using a modificationof the models and technique of Spadaro (1996) and correlated to overall sensorytenderness scores for each compression temperature. ISTFPR, FSTPF and EDPR valuesregressed against overall sensory tenderness produced higher R-square values (R2 = 0.71at 4.4????C and R2 = 0.70 at 10????C) than prediction equations using WBSF (R2 = 0.65). Thesignificance of this study was that sensory tenderness could be predicted rapidly andmore accurately on intact raw loin samples using a nondestructive probe measurementthan could be predicted with WBSF. This innovative technique could potentially beused as a selection tool to ensure beef tenderness, be integrated into an on-line USDAQuality Grading system and be utilized as a powerful non-destructive research technique.
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