A BIOTECHNOLOGICAL PROCESS FOR THE VALORIZATION OF FISH WASTE

Thirty-two strains of yeasts (Saccharomyces cerevisiae and Candida sp. ) and 14 strains of lactic acid bacteria (Lactobacillus plantarum and Pediococcus acidilactici) were screened on fish waste supplemented wit h molasses to select suitable combinations for fish silage fermentatio n. The parameters studied were molasses concentration, pH and temperat ure. Microbiological counts including standard plate count, coliforms, enterococci, staphylococci, Salmonella, Clostridium, lipolytics, prot eolytics, yeasts and moulds were made. In parallel, physico-chemical a nalyses, including pH, dry matter, ash, total nitrogen (TN), total non -protein-nitrogen (NPN), total volatile nitrogen (TVN), lipids, reduci ng sugars and trimethylamine (TMA) were also carried out on the materi al before the fermentation and on the product. Results indicated that the most suitable conditions for the fermentation were 30% of molasses at pH 5.2 and at 26-28-degrees-C. The product was free of coliforms a nd Salmonella. The chemical determinations showed a net decrease of th e pH, low TMA content and low total volatile nitrogen, but a new incre ase in reducing sugars in the product. Non-protein-nitrogen was high i n the product relative to the raw material.