LIPID AND PROTEIN-CHANGES DURING THE ENSILAGE OF BLUE WHITING (MICROMESISTIUS-POUTASSOU RISSO) BY ACID AND BIOLOGICAL METHODS

Fish waste is a potential source of protein for animal nutrition. Ensi lage could provide an advantageous means of upgrading these residues. Careful control of the degree of proteolysis and lipid oxidation is re quired to produce silages of high nutritional value. This paper studie s the changes in lipids and protein during storage (15 days) of acid s ilages (with 0, 0.25 and 0.43%, w/w, of formaldehyde) and biological s ilages (with 10 and 20% molasses or dehydrated whey) prepared from blu e whiting. A remarkable reduction in protein solubilisation values was achieved by adding formaldehyde. However, formaldehyde addition led t o an increase in the peroxide value of the oil extracted from the sila ges. Ensiling by biological methods seems promising. It yielded both a considerable reduction in protein solubilisation and in basic volatil e nitrogen when compared with acid ensilage. In addition, the oil from biological silages had lower peroxide values than the oil from acid s ilages with added formaldehyde. (C) 1998 Elsevier Science Ltd. All rig hts reserved.