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Authors
Abstract(s)
Previous meta-analytical work estimated that in Portuguese meat products intended to be eaten cooked, the overall occurrence of Salmonella spp. was 9.7% (95% CI: 7.0–13.4%). One of these meat products is alheira, which is a fermented sausage made of poultry/pork meat, bread and seasonings. The main objective of this study was to investigate prevalence, numbers and serovars of Salmonella spp. in alheira sausages artisanally produced in Bragança, Portugal. This work was undertaken in three stages: (i) sampling of 52 alheiras from market fairs and local shops/supermarkets; (ii) detection of Salmonella using culture methods and enumeration by MPN; and (iii) molecular confirmation of isolates (invA and randomly-cloned chromosomal fragment), and typing of S. Enteritidis (SefA), Typhimurium (fliC) or Pullorum (glgC) by PCR. A comparison of the intrinsic properties and microbial quality/stability between unpacked unbranded alheiras and vacuum-packed alheiras was also conducted.
Analysis of 52 sausage samples revealed the presence of Salmonella spp. in 10 samples (incidence of 0.192; 95% CI: 0.108–0.319), although all of these positive samples were unpacked sausages from traditional fairs (n=21), indicating therefore the higher Salmonella prevalence in alheiras sold in these establishments (incidence 0.476; 95% CI: 0.283–0.676). Salmonella mean concentration in positive enriched samples was 1.792 log MPN/g (s.d 0.916 log MPN/g). All of the 33 biochemically- and serologically-confirmed isolates coded for the invA gene. Multiplex-PCR revealed that only 3 of the positive isolates had the presence of SefA genes; which indicated that 9.1% of the isolates belonged to Enteritidis; while 20 isolates (60.60%) belonged to Typhimurium since they coded for fliC gene. The other 10 isolates (30.3%) were of serovars different from Enteritidis/Typhimurium/Pullorum. From the positive alheiras, Enteritidis or Typhimurium serovar was recovered from two samples, while the other samples harboured at least two serovars.
Salmonella continues to be a frequent contaminant of alheiras produced in Bragança, and, in particular, of those sold in market fairs (47.61%). Not unexpectedly, Typhimurium and Enteritidis represented the prevailing serovars (~70%) since they are linked to pork and poultry meat, the main raw materials of alheira. In addition, it could be inferred that unbranded, unpacked alheiras traditionally sold in market fairs are very likely to be produced under poor hygienic conditions, because of the significantly higher levels of total coliforms that were recovered from unpacked alheiras (7.958 log CFU/g; s.d. 0.948 log CFU/g) in comparison to branded vacuum-packed alheiras (5.423 log CFU/g; s.d. 1.264 log CFU/g). Unpacked alheiras also presented higher counts of Pseudomonas spp. (5.687 log CFU/g; s.d. 0.100 log CFU/g) and psychrotrophic bacteria (7.977 log CFU/g; s.d. 0.726 log CFU/g) than vacuum-packed alheiras (4.527 log CFU/g; s.d. 0.336 log CFU/g; and 6.969 log CFU/g; s.d. 0.295 log CFU/g, respectively), which suggested that the unpacked alheiras have generally a shorter shelf-life, and, more importantly, that both hurdles, vacuum-packaging and cold storage, are key in delaying microbial degradation in this product.
This work has evidenced that microbial stability and safety of the alheiras elaborated by the artisanal producers are not ensured. Thus, artisanal producers must be urgently informed on the implementation of preventive and corrective actions in their current manufacturing processes and hygiene practices; whereas consumers must be advised to fully cook alheira sausages before consumption.
Description
Mestrado de dupla diplomação com a Université Libre de Tunis
Keywords
Salmonella spp. Alheira