Microbiological and sensory quality of salmon products from retail in Leipzig

Cold-smoked and Graved salmon are perishable foods that are very popular among consumers. In 2017, 15 samples of cold-smoked and 10 of Graved salmon from the Leipzig retail trade were tested for microbiological and sensory quality as well as pH-value on the last day of consumption date. The microbiological investigations included the parameters total viable count, lactic acid bacteria, Enterobacteriaceae, Listeria (L.) monocytogenes and sulfite-reducing Clostridia. In smoked salmon a mean total viable count of log(10) 4.50 was found and for Graved salmon of log(10) 5.34 cfu/g. The median value for the number of lactic acid bacteria was log(10 )4.46 (smoked salmon) and log(10 )5.21 cfu/g (Graved salmon), for Enterobacteriaceae at log(10) 3.60 (smoked salmon) and at log(10) 3.52 cfu/g (Graved salmon). L. monocytogenes was detected in 2 samples of each sort of salmon and sulfite-reducing clostridia in one of the Graved salmon samples. Maldi-TOF MS was used for the differentiation of the main germ flora. Lactobacillus curvatus, Carnobacterium maltaromaticum, Brochothrix thermosphacta, Candida zeylanoides and Serratia spp. were most frequently found. Sensory examinations were performed based on the DLG sensory score (DLG, 2016). As a result, 44 % of the samples achieved scores of 4.B to 4.0 and 3.9 to 3.1 respectively. 84 % of the samples showed deviations in taste, which were significant in 16 % of them. Only one smoked salmon sample was of impeccable quality and scored 5 points. The pH values of the salmon samples varied between 5.70 and 6.11. The results show that cold smoked and Graved salmon may be contaminated with various spoilage microorganisms. L. monocytogenes monitoring must be implemented at all stages of production with the aim to reduce its contamination during manufacturing and in the final products.