Microbiological safety of Portuguese dry-fermented chouriço sausages as affected by processing and physicochemical factors

In order to identify the risk factors and main differences of the manufacturing technology of Portuguese chouriço dry-fermented sausage leading to the variable levels of Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in the product, microbiological and physicochemical characterisation of chouriço sampled at five stages of production was performed. Six production batches were surveyed from each of two factories, one of them used curing salts and polyphosphate in their formulation. The results suggest that mixing and maceration are critical points of the process since Enterobacteriaceae, S. aureus and L. monocytogenes could significantly increase until the end of such stages. Sausages formulated with nitrite and polyphosphate were found to have a delayed fermentation; which was responsible, to a certain extent, for the increase in Enterobacteriaceae and pathogens’ counts from raw meat to the end of maceration. On the contrary, the better acidification process of nitrite-free sausages led to lower counts of S. aureus and L. monocytogenes in the final products. Nitrite had a strong effect on reducing Enterobacteriaceae during smoking and also contributed to the control of L. monocytogenes, while it showed no effect on the growth of S. aureus in chouriço. There is a need to standardise the traditional elaboration process of chouriço, to optimise the initial acidification process, and to guarantee the high microbiological quality of ingredients, sanitisation of equipment, and good hygiene practices of operators.