Physico-chemical and biochemical modifications of Mytilus galloprovincialis after harvesting

摘要

It is well known that the most important life functions of mussels, such as nutrition, respiration and excretion, are based on filtration (Morse and Zardus, 1997, p. 33). Obviously, harvesting stops this mechanism and induces a drastic reduction in the mussel metabolism and isolation from the outer environment in order to maintain a small volume of intravalvular liquid (IL) sufficient for respiratory activity. However, the amount of IL decreases during storage, probably as a consequence of the removal of catabolites. For this reason, measurement of the volume of IL is frequently used to assess the degree of freshness of mussels (Sebastio, 1957; Sigovini and Almerigogna, 1983; Malandra et al, 1995), The decrease of IL is also affected by storage temperature since a temperature lower than +6 deg C can reduce their viability while a temperature over +6 deg C increases the production of catabolites with a consequent faster loss of IL (Malandra et al., 1995). In addition, in a previous study we observed a trend of decrease in IL not well correlated to the storage time, since the mussels are able to absorb a small amount of fluid through their byssus, at the 3rd-4th day after harvesting (Panebianco et al, 2002). Considering that the above mechanism could be the basis of others complex systems of adaptation to stress on storage, the aim of this work was to carry out a measurements of some physical, chemical and biochemical parameters of mussels during storage at +6 deg C.