Near-Infrared Spectroscopy for Rapid Determination of Physicochemical Properties of Fermented Fish Sauce (‘Nam Pla-Ra’)

Research background. Thai community product quality standards have been established for nam pla-ra, which require at least 4 % protein and 12 % sodium chloride. Determining the protein and NaCl contents requires chemicals and is time-consuming. In addition to reporting protein and salt content, other quality controls must also be carried out. Thus, the objective of this research is to develop predictive models for the determination of physicochemical properties of nam pla-ra using near-infrared spectroscopy (NIRS) for fast and simultaneous multi-parameter prediction. Experimental approach. The physicochemical values of commercially available fermented fish sauce (‘nam pla-ra’ in Thai) were evaluated to develop predictive models for determining physicochemical values and developing models to categorize samples. The model was developed and tested based on the seven parameters: total soluble solids (TSS), pH, L*, a*, b*, NaCl, and protein content. Results and conclusions. The predictive models for pH and colour (L*, a*, b*) could be used for screening, based on their coefficients of determination (R2=0.73–0.81; SEP=0.15–0.94). The model for determining protein content (R2=0.86; SEP=0.44) is suitable for screening, routine quality control, and research applications. In contrast, the TSS and NaCl models (R2=0.97–0.98; SEP=0.41–0.61) demonstrate high predictive performance and can be reliably applied to all analytical tasks, including screening, routine quality control, and research purposes. The physicochemical properties of nam pla-ra could be predicted accurately using TSS, colour (L*, a*, b*), NaCl and protein content. There was no significant (p>0.05) difference between the quality values obtained from the predictive model and the reference method, except for the pH value. Novelty and scientific contribution. NIRS showed potential in predicting the physicochemical properties of nam pla-ra using TSS and colour (L*, a*, b*) in the range 1000–2500 nm, and NaCl and protein contents in the selected ranges 1000–1889 and 2031–2408 nm, respectively. Furthermore, these findings demonstrate the potential of NIRS as a rapid, non-destructive, environmentally friendly and reliable analytical tool for determining the properties of nam pla-ra. NIRS can contribute to ensuring product consistency and facilitating standardisation in the fermented fish sauce industry. Such applications enhance food safety and consumer confidence.