The Potential of Raman Spectroscopy as a Rapid Method for Monitoring Shelf Life and Freshness of Refrigerated Rainbow Trout Fillet

Background: Rainbow trout (Oncorhynchus mykiss) is among the most commercially important freshwater fish species worldwide. Rainbow trout fillets are recognized for their high nutritional value and beneficial biological properties. However, fresh fish is a highly perishable food with a limited shelf life. Ensuring consistent quality and safety of fresh fish products remains a critical challenge for processors and suppliers. Among non-destructive quality evaluation techniques, Raman spectroscopy emerges as a promising approach for quality and safety monitoring in the food industry. Despite its proven effectiveness, Raman spectroscopy remains significantly understudied for assessing freshness and shelf-life in fish products. This research gap was addressed by providing novel insights into the application of Raman spectroscopy for fish freshness monitoring.

Purpose: To investigate the potential of Raman spectroscopy for assessing the shelf life and freshness of refrigerated rainbow trout fillets, and to determine key spectral characteristics that enable monitoring of product quality changes during storage.

Materials and Methods: The study object was refrigerated rainbow trout (Oncorhynchus mykiss) fillets stored at +2±2 °C. The shelf-life assessment, freshness evaluation and quality monitoring were performed using a Nanoscope NS100 series Raman spectrometer with 785 nm excitation wavelength and 100-3200 cm⁻¹ spectral range. Measurements were conducted during 16 days of refrigerated storage.

Results: The Raman spectral analysis demonstrated distinct variations in the spectra of rainbow trout samples and corresponding to different storage durations, revealing lipid oxidation levels. The lowest intensity was observed in fresh samples stored for 0–3 days, enabling clear differentiation from other groups. Sample fluorescence was detected during the analysis, introducing additional noise to the spectra. The 3D mathematical model demonstrated the highest percentage of total variance (92%) for chilled rainbow trout.

Conclusion: The obtained results demonstrate the potential of Raman spectroscopy as a rapid-assessment and non-destructive monitoring techniques for fish quality and shelf-life evaluation. This method holds practical significance for food safety regulatory authorities and consumers. Successful implementation of the technique requires minimization of fluorescence background interference, including the application of chemometric approaches, which would improve the accuracy of predictive models.

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