Raman, near-infrared and fluorescence spectroscopy for determination of collagen content in ground meat and poultry by-products

Raman, near-infrared and fluorescence spectroscopy were evaluated for determination of collagen content in ground meat. Two sample sets were used (i.e. ground beef and ground poultry by-products), and collagen concentrations (measured as hydroxyproline) varied in the ranges 0.1-3.3% in the beef samples and 0.4-1.5% in the poultry samples. Similar validation results for hydroxyproline were obtained for NIRS (R-2 = 0.82 and RMSECV = 0.11%) and Raman (R-2 = 0.81 and RMSECV = 0.11%) for the poultry samples. For the beef samples, NIRS obtained slightly less accurate results (R-2 = 0.89, RMSECV = 0.25%) compared to Raman (R-2 = 0.94, RMSECV = 0.19%), most likely due to less representative sampling. Fluorescence spectroscopy gave higher prediction errors (RMSECV = 0.50% and 0.13% for beef and poultry, respectively). This shows that Raman spectroscopy employing a scanning approach for representative sampling is a potential tool for on-line determination of collagen in meat.