Evaluation of near-infrared (NIR) and Fourier transform mid-infrared (ATR-FT/MIR) spectroscopy techniques combined with chemometrics for the determination of crude protein and intestinal protein digestibility of wheat

The potential of using the near-infrared (NIR) and Fourier transform mid-infrared (ATR-FT/MIR) spectroscopy for the determination of intestinal crude protein (CP) digestibility (IPD) of wheat was evaluated. For CP, the best NIR model showed an excellent prediction performance (R-2 = 0.98); the best MIR model also gave an excellent prediction performance (R-2 = 0.96). Regarding to IPD, the best model obtained by NIR technique showed approximate quantitative predictive ability (R-2 = 0.68), and the best model generated by MIR technique obtained similar prediction performance (R-2 = 0.67). NIR models generally showed better predictive abilities than MIR models, which may be due to the MIR spectra record fundamental molecular vibrations and can be more easily affected by multiple interferences. The amide I and II bands played important roles in the development of PLS models for CP and IPD. Results from this study demonstrated the potential of using IR spectroscopy for the prediction of nutrient digestibility while more efforts are required to improve the performance of NIR and ATR-FT/MIR spectroscopy in predicting the IPD of wheat.