Spoilage and Pathogenic Bacteria Isolated from Two Types of Portuguese Dry Smoked Sausages after Shelf-life Period in Modified Atmosphere Package

Members of the bacterial population of two types of Portuguese dry smoked sausages (chouriços) were identified and characterized. A total of 77 isolates were recovered from chouriços type Alentejano and Ribatejano, after 120 days at 20 ± 5 oC in modified atmosphere package (55 % N2/45 % CO2) using non-selective and selective media. Based on phenotypic (cell morphology and fermentation profile) and genotypic (16SrDNA sequencing) characters, the isolates were grouped into the following genera: Bacillus, Enterococcus, Clostridium, Staphylococcus, Pediococcus, Lactobacillus and Paenibacillus. The species identified were: Enterococcus faecium (24.7 %), Bacillus subtilis (23.4 %), Staphylococcus epidermidis (14.3 %), B. cereus (7.8 %), Pediococcus acidilactici (6.5 %) Bacillus pumilus (6.5 %), Clostridium bifermentans (3.9 %), B. licheniformis, and Enterococcus faecalis (2.6 %). Major differences observed between the two varieties of chouriço were the absence of Pediococcus species and the presence of high numbers of isolates identified as Staphylococcus epidermidis in chouriço type Alentejano and, the high incidence of Bacillus species in sausage type Ribatejano. Differences found between products may be due to spices formulation in each type of product, the type of natural casings used and, the hygienic quality of the raw meat.