GC×GC-MS Analyzes Flavor and Lipid Changes in Irradiated Rainbow Trout

Research was conducted investigating the effects of electron beam irradiation at doses of 1, 3, 5, and 7 kilogray (kGy) on cold fresh rainbow trout meat, using non-irradiated samples as a control. Changes in sensory scores, volatile flavor compounds, and lipids were analyzed using comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) and untargeted lipidomics. A paper based on this study was published in Food Chemistry: X.¹

Highly favored by consumers worldwide because of its tender texture and high content of proteins and unsaturated fatty acids, cold fresh rainbow trout meat is susceptible to microbial contamination, oxidation, and other factors during storage and transportation, which can lead to quality deterioration of quality and changes in flavor.^2,3 Various preservation technologies have been developed to extend the shelf life of trout meat, including electron beam irradiation, which has shown significant advantages in the prolonging of product shelf life and the safeguarding of food safety.⁴ The interaction between high-energy electrons and lipid molecules during irradiation, however, may result in the triggering of oxidative cascades, which can alter flavor precursors in the muscle matrix.⁵ In current industrial applications, the selection of electron beam irradiation doses in current industrial applications is often guided primarily by efficiency of sterilization, with not enough consideration focused on its impact on volatile flavor compounds and the underlying lipid components. This oversight, in the opinion of the researchers, may ultimately compromise product acceptability and market competitiveness.¹

The researchers reported that the results of their study revealed that irradiation at doses ≥3 kGy significantly reduced sensory scores. GC×GC-MS analysis indicated an increase in the total content of volatile flavor compounds after irradiation. Specifically, at doses ≥3 kGy, levels of lipid oxidation products-such as hexanal, (R)-2-octanol, and (S)-2-octanol-increased significantly (P < 0.05). In addition, lipidomics analysis identified 583 differential lipids across treatment groups, revealing decreases in phosphatidylcholine, triglyceride, and diglyceride levels, alongside an increase in phosphatidylethanolamine following irradiation.¹

“These findings,” write the authors of the study,¹ “demonstrate that electron beam irradiation promotes volatile compound formation by accelerating lipid oxidation. While doses below 3 kGy did not substantially alter flavor or sensory quality, doses of 3 kGy or higher induced a distinct "irradiation odor", ultimately leading to a marked reduction in acceptability.”

The researchers state that their study only concentrated on the immediate effects of electron-beam irradiation at varying doses on the lipid composition and volatile flavor compounds of cold fresh rainbow trout meat, and believe that any future research should systematically investigate how different irradiation doses influence microorganisms, lipids, and flavor compounds in rainbow trout during storage. Furthermore, the application of metabolomics may help clarify the specific lipid metabolic pathways affected by different irradiation doses and thereby inform the development of “flavor-friendly” irradiation protocols. Finally, the researchers suggest that future study shouldsystematically examine the potential impact of protein oxidation on flavor, as this was not addressed in the present study.¹

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References

1. Gong, F.; Xu, B.; Yang, L. et al. Revealing the Changes in Lipids, Volatile Flavors, Sensory Effects and their Correlations in Cold Fresh Rainbow Trout Meat Under Different Electron Beam Irradiation Doses Using Lipidomics and Flavoromics. Food Chem X 2026, 35, 103717. DOI: 10.1016/j.fochx.2026.103717
2. Cengiz, N.; Guclu, G.; Kelebek, H. et al. GC-MS-Olfactometric Characterization of Key Odorants in Rainbow Trout by the Application of Aroma Extract Dilution Analysis: Understanding Locational and Seasonal Effects. Food Chem. 2023, 407, 135137. DOI: 10.1016/j.foodchem.2022.135137
3. Mozaffari, P.; Pashangeh, S.; Berizi, E. et al. Potential of Nanochitosan Coating Combined with Walnut Green Husk to Improve the Preservation of Rainbow Trout (Oncorhynchus mykiss) During Refrigerated Storage. Environ Res. 2022, 214 (Pt 3), 114019. DOI: 10.1016/j.envres.2022.114019
4. Gautam, R. K.; Venugopal, V. Electron Beam Irradiation to Control Biohazards in Seafood. Food Control2021, 130, 108320. DOI: 10.1016/j.foodcont.2021.108320
5. Zhang, J.; Zhang, Q.; Fan, J. et al. Lipidomics Reveals Alterations of Lipid Composition and Molecular Nutrition in Irradiated Marble Beef. Food Chem X. 2023, 17, 100617. DOI: 10.1016/j.fochx.2023.100617