A BIOTECHNOLOGICAL PROCESS FOR THE VALORIZATION OF FISH WASTE

FAID M. KARANI H ELMARRAKCHI A and ACHKARI-BEGDOURI A.

ABSTRACT

Thirty two strains of yeasts (Saccharomyces cerevisiae and Candida sp) and 14 strains of Lactic acid bactaria (Lactobacillus plantarum and Pediococcus acidilactici) were screened on fish waste supplied with molasses to select the suitable combinations for the fish silage fermentation. The parameters studied were nolasses cocentration, pH and temperature. Microbiological determinations including standard plate count, colifroms, enterococci, staphylococci, Salmonella, Clostridium, lipolytics, proteolytics, yeasts and moulds were determined. In parallel, physico-chemical analyses including pH, Dry matter, Ash, total nitrogen (TN), total non proteic nitrogen (NPN), total volatil nitrogen (TVN), lipids, reducing sugars and trimethyl amine (TMA) were also carried out on the product before the fermentation (raw material) and on the obtained product. Results indicated that the most suitable conditions for the fermentation were a proportion of 30 % of molasse at pH 5.2 and at 26-28 °C. The obtained product was free of coliforms and Salmonella. The chemical determinations showed a net decrease of the pH, low levels of the trimethylamine content in the obtained product and the total volatile nitrogen with a net increase in reducing sugars. Non proteic nitrogen was high in the product relatively to the raw material. The acid degree value was also high relatively tot he initial product.