Definition of a standard protocol to determine the growth potential of Listeria monocytogenes and Yersinia enterocolitica in pork sausage produced in Abruzzo Region, Italy

Pork meat products consumed raw or after a short period of fermentation can be considered at risk for food safety. Sausages (fresh sausage made from pork meat) are produced in several Italian regions, with variation in ingredients. In some Italian Regions, including Abruzzo, these products are frequently consumed raw or undercooked, after a variable period of fermentation. The European Community food regulation promotes the use of challenge tests to determine safety levels. This study is aimed to ensure safety of Abruzzo’s sausages, compared with growth potential (δ) of Listeria monocytogenes and Yersinia enterocolitica, and also aims to define an experimental standard protocol document to carry out challenge tests. Guidelines classify ready-to-eat foods in categories that are able to support (δ>0.5 log₁₀ ufc/g) and not support (δ≤0.5 log₁₀ ufc/g) the growth of Listeria monocytogenes. The products were manufactured according to traditional recipes and were contaminated in laboratory. Results from the experiment yielded information useful to assess the ability of these products to support the growth of pathogenic microorganisms. The batches of sausages were stored at 8, 12, 18 and 20°C to get statistical evaluation. The results showed that, despite the conditioning of the storage temperature and the level of water activity, both organisms remain in the product in concentrations similar to those leading or being able to increase its charge. In particular, the period of greatest consumption of this product (7/8 days of preparation) corresponds to the period of greatest growth of pathogenic microorganisms studied, except for those stored at a temperature of 8°C, which are safer for the consumer.