Investigating potential freshness indicators for packaged oysters through multivariate statistical analysis

Pacific oysters (Crassostrea gigas) are globally renowned shellfish. In South Korea, oysters are commonly packaged with filling water in polyethylene bags. Previous studies have proposed various freshness and quality parameters for oysters, including pH, volatile basic nitrogen content, glycogen content, and viable cell count. We aimed to identify the objective indicators of oyster freshness during storage and distribution using metabolomic analysis and multivariate statistical techniques. Packaged oyster samples were analyzed for metabolites using gas chromatography-mass-spectrometry during 9-days storage at 5 °C or 15 °C. Additionally, the pH, turbidity, and soluble protein content of the filling water were measured. Multivariate statistical analyses, including principal component analysis, partial least squares discriminant analysis, and orthogonal projections to latent structure-discriminant analysis revealed statistically significant results, demonstrating metabolite clustering based on storage duration. In conclusion, this study introduced crucial freshness indicators for stored or distributed oysters by utilizing metabolomic analysis and multivariate statistical techniques.