Effect of morphometric variables and natural microbial load on the survival time of live Mytilus galloprovincialis during postharvest cold storage

This study investigated the relationships between morphometric characteristics, microbiological parameters, pH changes, and survival rates of Mediterranean mussels (Mytilus galloprovincialis) during post-harvest storage at +4°C. Mussels were categorized into three size groups based on shell length: large (63.92-80.19 mm), medium (48.51-62.63 mm), and small (30.08-47.75 mm). Total heterotrophic aerobic bacteria (THAB), Enterobacteriaceae, and Vibrio sp. counts were monitored over a 16-day storage period, along with pH changes and survival rates. Results demonstrated significant size-dependent variations in survival, with larger specimens showing superior viability throughout storage. THAB counts increased continuously across all groups, while Enterobacteriaceae levels remained relatively stable in medium and small groups. Vibrio sp. counts decreased in large specimens but remained stable in other groups. Strong negative correlations were observed between survival rates and both THAB (r: -0.854, p<0.001) and Enterobacteriaceae (r: -0.777, p<0.001) counts. Principal component analysis revealed that the first two components explained 83% of total variance, with physical dimensions primarily influencing PC1 (56.5%) and yield-related traits, pH, and THAB characterizing PC2 (26.5%). By day 16, medium and small groups reached 0% survival, while large specimens maintained partial survival. These findings suggest that mussel size significantly influences post-harvest survival and should be considered when developing storage protocols. Future research should focus on optimizing storage conditions through combined approaches of temperature control, modified atmospheres, and periodic water exposure, particularly considering morphometric variables.