Refrigerated transport modulates the health status and nutritional quality of Mediterranean mussels (Mytilus galloprovincialis): A case study from the western Adriatic Sea

Mediterranean mussels (Mytilus galloprovincialis) are a cornerstone of Italian aquaculture, yet their quality and survival can be affected by post-harvest handling and long-distance refrigerated transport. This study investigated the effects of a 17-hour-simulated transport at 7 ± 1 ◦C on mussel health status and quality, considering the position of mussels within stacked packaging layers (top, intermediate, and bottom). Results evidenced that the simulated transport conditions or the position within the pallet did not affect mussels’ marketable indexes (condition index, edible fraction yield, shell incidence) but were able to affect the mussels’ nutritional profile. In fact, mussels after transport exhibited reduced dry matter, crude protein, and crude lipid contents, coupled with fatty acid remodeling (mainly a decrease in palmitic acid and a parallel increase in n3-polyunsaturated fatty acids), regardless of their position within the pallet. These variations reflected the physiological mobilization of endogenous reserves to maintain basal metabolic functions during transport in emersion conditions as well as an active homeoviscous adaptation to counteract the reduction in membrane fluidity induced by the lower temperature. Interestingly, that fatty acid remodulation resulted in improved lipid quality indices (lower atherogenicity and thrombogenicity indexes, higher h/H ratio) leading to a more favorable nutritional profile. Finally, the simulated transport conditions majorly affected the health status of the mussels located at the bottom layers, possibly interested by the synergic effect of cold stress and hypoxia. In fact, mussels collected from these layers were characterized, at gills level, by an upregulation of markers involved in cellular (hsp70) and oxidative (sod1 and cat) stress together with a higher incidence of histopathological indexes compared to those from the top and intermediate layers. These findings suggest that short-term refrigerated transport induces physiological adjustments to extend their period of survival in adverse conditions, that were exacerbated in mussels located at the lowest levels of the pile