Research of quality indices for cold-smoked salmon using a stepwise multiple regression of microbiological counts and physico-chemical parameters

Aims: The aim of the study was to assess the relationships between the rema ining shelf-life (RSL) of cold-smoked salmon and various microbiological an d physico-chemical parameters, using a multivariate data analysis in the fo rm of stepwise forward multiple regression. Methods and Results: Thirteen batches of French cold-smoked salmon were ana lysed weekly during vacuum-packed storage at 5 degreesC for their lipid, wa ter, salt, phenol, pH, total volatile basic nitrogen (TVBN) and trimethylam ine contents, total psychrotrophic count, lactic acid bacteria, lactobacill i, B. thermosphacta, Enterobacteriaceae and yeast counts. At the sensory re jection time, the flora was dominated by lactobacilli, lactobacilli/Enterob acteriaceae or Carnobacteria/B. thermosphacta. Shelf-life was very variable (1->6 weeks) and was related to the initial Enterobacteriaceae load (P < 0 .05), depending on hygienic conditions in the smokehouse. High correlations existed between the RSL and lactobacilli count (P < 0.01), yeast count (P < 0.05) and TVBN concentration (P < 0.01). A polynomial fitting the RSL as a function of those three factors was proposed (R = 0.80). Assuming that la ctobacilli count could not exceed 10(9) cfu g(-1), a minimum of 36 mg-N 100 g(-1) was necessary for a product to be rejected, with a yeast count of 10 (4) cfu g(-1). Conclusions: Estimation of cold-smoked salmon quality is possible by measur ing three parameters: lactobacilli and yeast counts and TVBN concentration. Significance and Impact of the Study: The technical content is important fo r the smoked salmon industry and for development of quality standards for c old-smoked salmon.