IMPORTANCE OF AUTOLYSIS AND MICROBIOLOGICAL ACTIVITY ON QUALITY OF COLD-SMOKED SALMON

The relative importance of autolysis and microbiological activity on s poilage of cold-smoked salmon and the origin of the chemical compounds hypoxanthine, acetic acid, trimethylamine and total volatile bases we re studied in a storage experiment of dry salted and injection-brined, vacuum-packed salmon with normal and reduced loads of microorganisms. Comparative studies of cold-smoked salmon with a reduced and normal l oad of microorganisms showed that microbiological activity caused prod uction of the characteristic spoilage odours and flavours, while the a utolytic enzymes from the fish tissue had major impact on the textural deterioration. Total volatile bases and hypoxanthine were produced in significantly higher levels in salmon with a normal bacterial load. S ixty-eight per cent of the hypoxanthine found in stored samples origin ated from microbiological conversion of inosine to hypoxanthine. The c oncentration of acetic acid only increased in samples with a normal lo ad. At the onset of spoilage, the microflora in dry salted salmon was dominated by marine vibrio in contrast to the injection brined product where a mixture of Enterobacteriaceae and lactic acid bacteria were p revalent. The different ratios of hypoxanthine produced to trimethylam ine also suggested that spoilage of salmon salted by the two methods w as caused by different microorganisms. Copyright (C) 1996 Published by Elsevier Science Ltd on behalf of the Canadian Institute of Food Scie nce and Technology