A review of the published quantitative risk assessment (QRA) models of L. monocytogenes in seafood was performed, with the objective of appraising the effectiveness of the control strategies placed along the food chain. Whereas all the 13 QRA models retrieved were of short scope, covering at most from end of processing to consumption; the majority (85%) focused on smoked or gravad fish. Since the modelled pathways commenced with the packaged product, none of the QRA models addressed cross-contamination events. Many models agreed on the fact that keeping the product’s temperature at 4.0-4.5 ºC leads to greater reductions in the final risk of listeriosis than reducing the shelf life by one week; and that the effectiveness of both measures can be surpassed by reducing the initial occurrence of L. monocytogenes in the product (at the end of processing). It is therefore necessary that future QRA models for RTE seafood contains a processing module that can provide insight into intervention strategies that can retard L. monocytogenes growth, such as the use of bacteriocins, ad-hoc starter cultures and/or organic acids, and other strategies seeking to reduce cross-contamination at the facilities, such as stringent controls for sanitation procedures. Since risk estimates were shown to be moderately driven by growth kinetic parameters, namely, the exponential growth rate, the minimum temperature for growth, and the maximum population density, further work is needed to reduce uncertainties about them.

Alheira is a naturally fermented meat sausage traditionally made in the Portuguese region of Trás-os-Montes. Lactic Acid Bacteria (LAB) have been found to be the dominant microorganisms in alheira. This study aimed: 1) to characterize technological features and in vitro antimicrobial activity of LAB isolates; and 2) to reveal associations between such phenotypic characteristics and the isolates genotypically identified to species level through amplification and sequencing of the 16S ribosomal gene. Sixty-two LAB isolates were identified and Enterococcus faecium was the most prevalent (32.3%), followed by Leuconostoc mesenteroides (19.4%) and Latilactobacillus sakei (17.7%), aligning with previous research on traditional Portuguese fermented meat sausages. The phenotypic analysis of LAB isolates indicated diverse acidification capacities, proteolytic activities, and inhibitory effects against foodborne pathogens. Comprising the technological attributes, L. paracasei and L. mesenteroides had higher proteolytic activity (3.46 and 3.43 mm), whereas E. faecium and L. paracasei stood out for their acidifying capacity, with mean pH after 6 h of 5.78 and 6.03, respectively. Overall, lactobacilli presented higher inhibition diameter against the pathogens Staphylococcus aureus, Listeria monocytogenes and Salmonella Typhimurium. Although the mechanisms for inhibition of pathogen growth needs to be further elucidated, these findings enhance our understanding of LAB diversity and functionality in alheira sausages, contributing to product safety and quality assessment.

A review of quantitative risk assessment (QRA) models of L. monocytogenes in produce was carried out, with the objective of appraising and contrasting the effectiveness of the control strategies placed along the food chains. Despite nine of the thirteen QRA models recovered focused on fresh or RTE leafy greens, none of them represented important factors or sources of contamination in the primary production, such as type of cultivation, water, fertilisers or irrigation method/practices. Cross-contamination at processing and during consumer’s handling was modelled using transfer rates, which were shown to moderately drive the final risk of listeriosis; highlighting therefore the importance of accurately representing the transfer coefficient parameters. Many QRA models coincided in the fact that temperature fluctuations at retail or temperature abuse at home were key factors contributing to increasing the risk of listeriosis. In addition to a primary module that could help assess current on-farm practices and potential control measures, future QRA models for minimally-processed produce should also contain a refined sanitisation module able to estimate the effectiveness of various sanitisers as a function of type, concentration and exposure time. Finally, L. monocytogenes growth in the products down the supply chain should be estimated by using realistic time-temperature trajectories, and validated microbial kinetic parameters, both of them currently available in the literature.