ESB - Teses de Doutoramento / Doctoral Theses
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Browsing ESB - Teses de Doutoramento / Doctoral Theses by Author "Campelos, Maria Isabel Pereira da Silva"
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- Hazards and control of risks in artesanal meat products in PortugalPublication . Campelos, Maria Isabel Pereira da Silva; Teixeira, Paula; Gibbs, Paul; Hogg, Tim"Salpicão de Vinhais" and "Chouriça de Vinhais" are traditional dry-fermented smoked meat sausages produced in Vinhais, a small region of Trás-os-Montes. The scientific knowledge of this sausage variety is limited. This work aims to collect scientific data that could, partially, fill the gaps in knowledge regarding these products, analyse the data and develop a risk-based study, according to an internationally accepted framework and finally, to explore the effect of hypothetical risk management measures on the safety of consumers, regarding traditional dry fermented meat smoked sausages. Seventy seven samples of ―Salpicão‖ and ―Chouriça de Vinhais‖ were purchased from producers, local markets and retail stores. Their microbiological and physical chemical characteristics were analyzed. The same analyses were performed on the products during the production processes. The raw materials and ingredients were also analyzed. Regarding the pathogenic flora, Staphylococcus aureus, spores of sulphite-reducing clostridia, Escherichia coli 0157:H7, Yersinia spp. and Salmonella spp., were not detected in any of the samples analyzed; Listeria monocytogenes was detected in 14.3% of the samples. The manufacturing process, namely fermentation, ripening/drying and smoking reduced the numbers of pathogen and hygiene indicator microorganisms. According to the Commission Regulation (EC) 2073/2005, 39% of the contaminated samples of ―Salpicão‖ and ―Chouriça de Vinhais‖ were able to support growth of L. monocytogenes. A quantitative microbiological risk assessment using a probabilistic model was developed. Considering the Portuguese population, with data obtained in this work, the calculated risk of listeriosis, for the intermediate age sub-population was 0.1297 cases per year, for the perinatal sub-population, 1.3695 cases per year, and elderly sub-population 0.1995 cases per year. This means that Traditional Dry Fermented Smoked Sausages constitute a low risk for the Intermediate Age and Elderly population (less than 1 case per annum) and an intermediate risk for the Perinatal populations, considering this last group of consumers as adult pregnant women (1-10 cases per annum). The effect of several putative risk management actions such as the adoption of a Performance Objective of 10 CFU/g, 1 CFU/g and 0.04 CFU/g reduced the risk of listeriosis for all sub-groups, at the end of shelf life, by 25.5%, 58.4% and 58.6%, respectively. The effect of bacteriocinogenic strain of Pediococcus acidilactici HA6111-2, previously isolated from ―alheira‖, was studied on both ―Salpicão‖ and ―Chouriça‖, in a challenge test against a cocktail of Listeria innocua, at pilot scale. A reduction of the numbers of Listeria innocua was achieved in all batches, being the biphasic equation the model that gave the better fit. The use of a bacteriocinogenic strain added to the batter reduced the risk of listeriosis for all sub-groups by 26.7%; obtaining a final product with aw below 0.92, supposedly below the growth limits of L. monocytogenes, reduces the risk by 8.6% in all sub-groups of population; the combination of the bacteriocinogenic strain and the limit of aw 0.92 reduces the risk by 41.0%. Traditional dry fermented smoked sausages present low to medium risk to the health of consumers. The use of more restrictive Performance Objectives during processing and/or distribution will result in a further reduction of risk. A more rigorous control of final product water activity and the use of a bacteriocinogenic bioprotective culture during production may contribute significantly to reducing the risk of listeriosis in consumers of these Traditional Dry Fermented Smoked Sausages (TDFSS).