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BackgroundFresh produce occupies an increasingly important place in the human food supply because of its health-promoting nutritional properties. Most fresh produce is eaten raw or after minimal processing and, consequently, pathogen contamination can represent a serious health risk. There has been an increase in foodborne outbreaks and cases associated with fresh produce, but literature data about the prevalence of pathogen contamination are inconsistent. This study was undertaken to assess the hygienic quality and the prevalence of the most common bacterial pathogens in fresh produce sold in retail markets in Sicily. A total of 125 samples of different types of vegetables were examined by standardized microbiological methods.ResultsThe aerobic mesophilic count ranged between 2 log and 7 log cfu g−1 and the Enterobacteriaceae counts between < 1 log and 6 log cfu g−1, with statistically significant differences between unprocessed and minimally processed products (p < 0.05). Escherichia coli was detected only in leaf vegetables at a concentration of 2 log - 3 log cfu g−1. Enterococci were found at a concentration of 2 log - 4 log cfu g−1. Coagulase positive Staphylococci and sulphite-reducing Clostridia were not detected in any sample. Three samples tested positive for Listeria monocytogenes, Yersinia enterocolitica and Salmonella veneziana.ConclusionOur study provides updated data on the microbiological quality of retail vegetables and confirms the need to implement strategies to increase microbial safety of fresh produce.

The main hypothesis of this work was that Sicilian forestry resources are suitable for the production of equipment to be used in cheese making and indigenous milk lactic acid bacteria (LAB) are able to develop stable biofilms providing starter and nonstarter cultures necessary for curd fermentation and cheese ripening, respectively. Hence, the present work was carried out with deproteinized whey to evaluate LAB biofilm formation on different woods derived from tree species grown in Sicily. Microbiological and scanning electron microscopy analyses showed minimal differences in microbial levels and compositions for the neoformed biofilms. The specific investigation of spp.,, , coagulase-positive staphylococci (CPS), and sulfite-reducing anaerobes did not generate any colony for all vats before and after bacterial adhesion. LAB populations dominated all vat surfaces. The highest levels (7.63 log CFU/cm) were registered for thermophilic cocci. Different colonies were characterized physiologically, biochemically, and genetically (at strain and species levels). Six species within the genera ,, , and were identified. The species most frequently present were and LAB found on the surfaces of the wooden vats in this study showed interesting characteristics important for dairy manufacture. To thoroughly investigate the safety of the wooden vat, a test of artificial contamination on new Calabrian chestnut (control wood) vats was carried out. The results showed that LAB represent efficient barriers to the adhesion of the main dairy pathogens, probably due to their acidity and bacteriocin generation. This study highlights the importance of using wooden vats for traditional cheese production and provides evidence for the valorization of the Sicilian forest wood resources via the production of dairy equipment.

bThree Lactococcus lactis subsp. cremoris strains were used to develop ad hoc biofilms on the surfaces of virgin wooden vats used for cheese production. Two vats (TZ) were tested under controlled conditions (pilot plant), and two vats (TA) were tested under uncontrolled conditions (industrial plant). In each plant, one vat (TA1 and TZ1) was used for the control, traditional production of PDO Vastedda della Valle del Belìce (Vastedda) cheese, and one (TA2 and TZ2) was used for experimental production performed after lactococcal biofilm activation and the daily addition of a natural whey starter culture (NWSC). Microbiological and scanning electron microscopy analyses showed differences in terms of microbial levels and composition of the neoformed biofilms. The levels of the microbial groups investigated during cheese production showed significant differences between the control trials and between the control and experimental trials, but the differences were not particularly marked between the TA2 and TZ2 productions, which showed the largest numbers of mesophilic lactic acid bacterium (LAB) cocci. LAB populations were characterized phenotypically and genotypically, and 44 dominant strains belonging to 10 species were identified. Direct comparison of the polymorphic profiles of the LAB collected during cheese making showed that the addition of the NWSC reduced their biodiversity. Sensory evaluation showed that the microbial activation of the wooden vats with the multistrain Lactococcus culture generated cheeses with sensory attributes comparable to those of commercial cheese. Thus, neoformed biofilms enable a reduction of microbial variability and stabilize the sensorial attributes of Vastedda cheese.

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