Assessment of tenderness of aged bovine gluteus medius muscles using Raman spectroscopy

A portable 671 nm Raman system was evaluated as a rapid and non-destructive device for the assessment of beef tenderness using 175 gluteus medius muscles (99 for calibration, 76 for validation) aged at -1 °C and 7 °C for fourteen days. Raman and shear force (SF) measurements were performed with the aged beef. The samples stored at -1 °C showed on average only slightly increased SF values. The correlation of Raman spectra with SF using partial least squares regression yielded cross-validated predictions of SF for both storage temperatures with coefficients of determination R(2)cv=0.33-0.79. Validation with independent samples resulted in predictions with R(2)val=0.33. Using thresholds between 30 and 49N, tough and tender samples could be discriminated with partial least squares discriminant analysis with 70-88% and 59-80% accuracy during cross-validation and validation, respectively. These results demonstrate the principle feasibility to predict the SF and thus toughness of raw, aged gluteus beef cuts with a portable Raman device showing potential for grading beef cuts.