During the manufacture of Italian salami, a traditional meat product, a sequence of hurdles like meat fermentation, air-drying, and long ripening processes are generally sufficient to inhibit the growth of most pathogens. Furthermore, Italian salami are traditionally produced by adding synthetic nitrates/nitrites to raw meat with safety and technological aims, even if controversial opinions about their use still remain, particularly in relation to the consumer demand for natural food products. In this context, the aim of the study was to investigate the inactivation of Listeria monocytogenes and Salmonella spp. during the manufacturing process of Milano-type salami made with different formulations to evaluate the contribution of the hurdles and the vegetable or synthetic additives on the inactivation of pathogens. Thus, a challenge study was performed dividing ca. 400 kg of Milano-type salami batter into three batches: Batch (A) without nitrates/nitrites; Batch (B) with vegetable nitrates, and Batch (C) with synthetic nitrates/nitrites. The batches were separately inoculated with L. monocytogenes and Salmonella spp. and the pathogens’ survival was evaluated during the fermentation, draining, and 70-day ripening of the Milano-type salami. The pathogen counts decreased in all tested conditions, even though the highest inactivation of L. monocytogenes and Salmonella spp. (p < 0.05) was observed when nitrates or nitrites were added to the batter. This study shows how the safety of these products cannot exclude the aspect of the hurdle technology during the process, which plays a major role in the reduction of pathogens, but additives like nitrates and nitrites allow for a greater margin of safety. Thus, further studies are needed to validate the use of natural compounds as alternatives to conventional preservatives in meat products. These results may provide new information to support food business operators in producing traditional foods with alternative preservatives and competent authorities in verifying the safety of the products made with natural compounds, and to control the process parameters responsible for the synergistic effect against pathogens such as L. monocytogenes and Salmonella spp.

Salmonella and Campylobacter ssp. are bacterial pathogens responsible for most foodborne infections in EU countries. Poultry serves as a reservoir for these pathogens, and its important role in the meat industry makes it essential to develop a rapid detection assay able to provide results in one day. Indeed, the rapid identification of foodborne pathogens is an important instrument for the monitoring and prevention of epidemic outbreaks. To date, Salmonella and Campylobacter screening is mainly conducted through molecular methods (PCR or real-time PCR) performed after 18–24 h long enrichments. In this study, we evaluated short enrichments (0, 2, 4, and 6 h) combined with a colorimetric loop-mediated isothermal AMPlification (LAMP) or real-time PCR to detect Salmonella and Campylobacter in poultry meat contaminated at different concentration levels (10¹, 10³, and 10⁵ CFU/g). Our results show that real-time PCR allows the detection of Salmonella and Campylobacter, even after shorter enrichment times than prescribed by ISO references; particularly, it detected Salmonella down to 10¹ CFU/g since T0 and Campylobacter from 10³ CFU/g since T0. Detection with LAMP was comparable to real-time PCR without the requirement of a thermal cycler and with shorter execution times. These characteristics make colorimetric LAMP a valid alternative when one-day results are needed, improving the timely identification of positive meat batches, even in the absence of specialized instrumentation.

An increasing trend among food business operators (FBOs) to extend the shelf life of Ready-To-Eat (RTE) fish products over 5 days, the duration usually assigned to this kind of product, has been observed recently. In this study, three independent challenge tests (food artificial contamination) were performed on tuna fillet, marinated salmon tartare, and cubed salmon, with the aim of calculating the maximum growth rate (V_max) of Listeria monocytogenes and estimating the time required to reach the legal limit of 2 log CFU/g, as established by European Regulation 2073/2005. The pathogen counts were fitted by the model of Baranyi and Roberts to calculate the V_max, which were 0.041, 0.020, and 0.039 log CFU/g·h⁻¹, respectively, for the tuna fillet, marinated salmon tartare, and cubed salmon at 10 °C. These results can help FBOs in assigning the correct shelf life based on hygienic practices during the process, product characteristics, and storage conditions. The time to reach the legal limit greatly depends on the starting concentration of the pathogen and on the storage temperature. The challenges for FBOs and the health authorities include reducing the contamination of L. monocytogenes, controlling the retail temperatures, and implementing the analytical tests for quick responses.

The behaviour of Listeria monocytogenes and Escherichia coli O157:H7 was studied during the manufacture and ripening of two traditional Italian Alps cheeses. Each cheese type was manufactured in a pilot plan from raw cow milk (without the addition of starter cultures) artificially inoculated with L. monocytogenes and E. coli O157:H7 to a final concentration of about 4 log CFU/mL. The pathogens were enumerated throughout the cheese making and ripening processes to study their behaviour. When the milk was inoculated with 4 Log CFU/mL, the pathogens counts increased in the first time during the manufacturing process and then remained constant, until the end of ripening, or decreased significantly. Results indicate that the environment and nature of food borne pathogens affected the concentration of the bacteria during the manufacturing and ripening process. Thus, the presence of low cells numbers of L. monocytogenes and E. coli O157:H7 in milk destined for the production of raw milk cheeses characterized by a cooking of the curd less than 48°C can constitute a hazard for the consumer.

Behaviour of Escherichia coli O157:H7 during the manufacture and ripening of an Italian traditional raw goat milk cheese

Ready-to-eat (RTE) fresh salads are widely consumed for their convenience and nutritional value, but they could represent a relevant food safety concern, as they do not undergo a lethal heat treatment before consumption, and furthermore, they may support the growth of Listeria monocytogenes during refrigerated storage. In this study, the growth potential of L. monocytogenes was evaluated by standardised challenge tests in five commercially available RTE salads: crispy lettuce, baby lettuce, a baby lettuce–spicy mustard mix, and two mâche products from different producers. Three different batches for each product were inoculated with a three-strain cocktail of L. monocytogenes at a target level of approximately 2–3 log CFU/g and stored under conditions simulating reasonably foreseeable refrigerated storage (7 °C for approximately two-thirds of their shelf life, followed by 10 °C for the remaining one-third), in accordance with ISO 20976-1 and EURL L. monocytogenes guidelines. The growth potential (Δ) was calculated as the difference between the highest mean L. monocytogenes concentration observed during storage and the mean of the initial concentration at time zero, both in three replicate samples; Δmax was defined as the highest Δ value among the tested batches. Crispy lettuce, baby lettuce, and the mixed salad supported the growth of L. monocytogenes, with Δmax values of 2.33, 2.60, and 3.65 log CFU/g, respectively. In contrast, both mâche products showed Δmax values ≤ 0.5 log CFU/g, indicating an inability to support pathogen growth under the tested conditions. These results demonstrate that the growth potential of L. monocytogenes in RTE salads is strongly product-specific and likely influenced by intrinsic characteristics and background microbiota, as well as by storage temperature. The findings underline the importance of strict temperature control and product-specific risk assessment to ensure compliance with microbiological criteria throughout shelf life and to mitigate the risk of listeriosis associated with RTE salads.