Comparison of two infrared spectroscopic methods for cheese analysis

Area of Science:

• Food Science and Technology
• Analytical Chemistry
• Spectroscopy

Background:

• Accurate determination of cheese composition (protein, fat, moisture) is crucial for quality control and product development.
• Traditional wet chemistry methods are time-consuming and labor-intensive.
• Spectroscopic techniques offer rapid, non-destructive alternatives for food analysis.

Purpose of the Study:

• To compare the efficacy of optothermal near-infrared (NIR) spectroscopy and Fourier transform mid-infrared-attenuated total reflection (FTIR-ATR) spectroscopy for quantifying cheese composition.
• To evaluate the accuracy and precision of both spectroscopic methods against standard wet chemistry analysis.
• To assess the practical advantages of each spectroscopic technique for routine cheese analysis.

Main Methods:

• Twenty-four cheese samples were analyzed using both optothermal NIR and FTIR-ATR spectroscopy.
• Reference values for protein, fat, and moisture content (weight percent) were determined using standard wet chemistry analysis.
• Predictive models were developed, and performance was evaluated using correlation coefficients and standard errors of prediction.

Main Results:

• Optothermal NIR spectroscopy achieved high prediction correlation coefficients (0.93–0.96) with low standard errors of prediction (2%–5%).
• FTIR-ATR spectroscopy yielded lower prediction correlation coefficients (0.81–0.92) and higher standard errors of prediction (4%–9%).
• Inhomogeneities within cheese samples, particularly fat droplets, likely contributed to the differences in prediction errors.

Conclusions:

• Optothermal NIR spectroscopy demonstrates superior performance for rapid and accurate determination of protein, fat, and moisture content in cheese.
• The ease of use, speed, simpler statistical analysis, and robustness of optothermal NIR instruments make them highly attractive for practical food analysis.
• FTIR-ATR spectroscopy is a viable but less accurate alternative for cheese composition analysis compared to optothermal NIR.