Effect of different farming sites and techniques on the growing performances and quality of Pacific oysters (Crassostrea gigas, Thunberg)

This research deals with the effects that different farming sites, containers and techniques produce on the growing performances, some quality parameters and shelf-life evolution of Pacific oysters (Crassostrea gigas). Aims of this research were: • to develop a proper experimental protocol useful for oysters commercial and in-conservation quality evaluation • to evaluate the suitability for oysters growing of two farming sites on the Tuscany coast (Orbetello Lagoon and open sea near Porto Ercole) • to evaluate the performance of oysters farmed in sea site utilising different kinds of containers • to evaluate the feasibility of a finishing period in the open sea (Porto Ercole) for oysters previously grown in the Orbetello Lagoon. Three trials were performed: - trial 1 was a preliminary study on the quality characteristics and on their changes during 10 days of 4 °C refrigerated storage of commercial sized oysters with different Italian origin (Orbetello Lagoon and open sea near Manfredonia, Foggia); - trial 2 was an experiment on the effect of different farming sites (Orbetello Lagoon and open sea near Porto Ercole) and different container typology (poche, lanterns, baskets) on oysters growing performances and commercial characteristics from spat to adult stage along a period of 14 months; - trial 3 was performed by transferring in the open sea site commercial sized oysters previously grown in the lagoon, using two different containers (baskets and lanterns); the growing performances and the commercial characteristics of the oysters as well as their quality characteristics and conservation performances during 10 days of 4°C refrigerated storage were evaluated. The best results for the growing performances and commercial characteristics were achieved by the oysters farmed in the lagoon, while the best container for growing in sea site resulted to be the basket. During the finishing period in the open sea site a general worsening of the commercial characteristics of the oysters occurred, while the fatty acids profile quality improved. The best container for oysters in-open-sea finishing resulted to be the lantern. Lagoon oysters reacted in a better way to the storage conditions, presenting a higher resistance to spoilage factors. They also have been judged by a panel test with a higher score both for appearance and flavour.