Mussel processing wastes as a fermentation substrate

Abstract

The Galician Rías Baixas (NW Spain) are a series of estuarine systems affected by the Galician upwelling (Fraga, 1981, 1991), whose primary productivity, reaching 260 g carbon/m2/year (Fraga, 1976), is among the highest in the world. The intense semiculture of mussels developed with regard to these conditions, now generates approximately 250 000 metric tons/year (almost half the world’s production), two thirds of which is found in a single system (the Ria of Arousa). Only part of this production is directed to fresh consumption, more than 60% — with a tendency to increase — being frozen or canned, by means of various processes involving a common first step of steam treatment that releases 300–500 1 of effluents per metric ton of raw treated mollusc. Due to a complete lack of insight, these mussel processing wastes (MPW), rich in organic matter, particularly glycogen, are dumped in the coastal waters, where they constitute an eutrophication factor that seriously affects the very medium that generates the resource