Microbiological quality and shelf life of cold-smoked salmon from three different processing plants

Whole fillets and slices of cold-smoked salmon from the same batch were vacuum packed and stored at 5 degrees C for up to 50 days, sampled regularly and analysed for sensory and microbiological changes. The experiment was performed twice with salmon from three different smokehouses. The taste panel rejected sliced salmon after 21-36 days and fillets after 32-49 days of storage with no apparent relation to the microflora or salt content (4.1-6.1% in the water phase!. Whole fillets developed the same spoilage characteristics, which included sweet, sour, bitter, faecal, ammonia and cabbage-like off-flavours, as sliced salmon but had a softer texture at the time of rejection. Plate count and Malthus detection times revealed that the microflora varied in numbers and composition among the three smokehouses. The microflora differed between fillets and sliced salmon, indicating the impact of the in-house flora on the size and composition of the microflora. Lactic acid bacteria, Enterobacteriaceae, psychrotrophic marine vibrio and Photobacterium spp. dominated the microflora of spoiled salmon. Use of conductometric measurements (Malthus) calibrated to traditional agar methods was not a suitable rapid microbiological method for determining the size and composition of the microflora, because of the variable microflora. (C) 1998 Academic Press Limited.