Microbiological and physicochemical profile of Italian steak tartare and predicting growth potential of Listeria monocytogenes.

In the present study, growth potential of Listeria monocytogenes in steak tartare samples taken at retail and belonging to 13 brands marketed in Northern Italy was investigated. The samples were submitted to microbiological and chemical-physical characterization. The data obtained were used as inputs for the application of the predictive microbiology software FSSP that allows the estimation of the growth of L. monocytogenes during the shelf-life. Lactic acid bacteria, the main component of the microflora, gave variable counts among the brands (from 3.38 to 6.24 log CFU/g). pH and aw values were always higher than 5.3 and 0.96, respectively, thus they could not be considered as single efficient hurdles to prevent the growth of L. monocytogenes according to the EC Reg. 2073/2005; the same was observed for salt content (constantly <2 %) and nitrites (not quantifiable in all the samples, even if declared in some labels). Nevertheless, the combination of all the hurdles, evaluated by predictive microbiology using critical development factors, resulted in an estimated growth <0.5 log CFU/g throughout the shelf life; this output allowed us to consider all the steak tartare analysed as unfavourable substrate for L. monocytogenes growth. The information obtained could be useful for tartare producers as well as for competent authority to evaluate the effective risk concerning these typology of products.

Sustainable pig diets: partial grain replacement with former food products and its impact on meat quality.

This study investigated the effects of salty and sugary former foodstuff products (FFPs) on the quality traits and meat composition of 36 male castrated pigs (Swiss Large White breed) as well as sensory characteristics of the loins. The animals were fed three different diets for both the growing (G) and finishing (F) phases: (1) a standard diet (ST), 0% FFPs; (2) a diet with 30% of sugary FFPs (e.g., chocolate, biscuits, cakes) as a replacement for traditional ingredients (SU); and (3) a diet with 30% of salty FFPs (e.g., bread, pasta, and breadsticks) as a replacement for traditional ingredients (SA). For a comprehensive assessment of meat quality, protein and fat content in the LD were analyzed. AA and FA profile were determined both in the LD and backfat. Meat quality traits such as pH and temperature, thawing, cooking and drip losses, and shear force have been evaluated. Then, pork loins have been assessed for sensory attributes by a trained sensory panel. The SA diet decreased 20:5 n-3 levels (P < 0.001) in the muscle and 22:5 n-3 levels (P < 0.05) in both muscle and backfat but increased (P < 0.05) the ratio of mono-unsaturated to saturated fatty acids compared to the ST group. Both the SU and SA diets elevated (P < 0.001) the n-6:n-3 fatty acids ratio compared to the ST diet. Dietary treatments did not affect other meat quality traits. Regarding sensory attributes, the loin from pigs fed with SU and SA diets were sweeter (P < 0.001). Loins of SA pigs were more tender (P < 0.001), had a more intense pork aroma (P < 0.001) and had more flavor (P < 0.01) compared to ST loins. Overall, the use of FFPs affected the fatty acid profile of pork while improving the sensory quality of the loins, with no negative effects observed on the technological and nutritional quality of the meat.

Pigs are ideal species to convert food losses, also named former food products (FFPs), into animal proteins. The present study investigated the impact of incorporating sugary and salty FFPs into the diets of growing and finishing pigs on meat quality and its sensory characteristics. Our study showed that, while technological meat quality remained largely unaffected, the dietary treatments led to slight alterations of meat and backfat fatty acids profile. Moreover, a panel test for sensory analyses revealed that loins from both the sugary and salty ingredients-fed pigs were perceived as sweeter, and loins from pigs fed salty ingredients were noted for increased tenderness, intense pork aroma, and flavor. Overall, FFPs inclusion into pig diets had no detrimental effects on technological or nutritional aspects of the meat, confirming their potential use as alternative animal feed.

Microbial Spoilage of Traditional Goose Sausages Produced in a Northern Region of Italy.

Recently, during the ripening of goose sausage, a defect consisting of ammonia and vinegar smell was noticed. The producer of the craft facility, located in Lombardia, a Northern region of Italy, asked us to identify the cause of that defect. Therefore, this study aimed to identify the potential responsible agents for the spoilage of this lot of goose sausages. Spoilage was first detected by sensory analysis using the "needle probing" technique; however, the spoiled sausages were not marketable due to the high ammonia and vinegar smell. The added starter culture did not limit or inhibit the spoilage microorganisms, which were represented by Levilactobacillus brevis, the predominant species, and by Enterococcus faecalis and E. faecium. These microorganisms grew during ripening and produced a large amount of biogenic amines, which could represent a risk for consumers. Furthermore, Lev. brevis, being a heterofermentative lactic acid bacteria (LAB), also produced ethanol, acetic acid, and a variation in the sausage colour. The production of biogenic amines was confirmed in vitro. Furthermore, as observed in a previous study, the second cause of spoilage can be attributed to moulds which grew during ripening; both the isolated strains, Penicillium nalgiovense, added as a starter culture, and P. lanosocoeruleum, present as an environmental contaminant, grew between the meat and casing, producing a large amount of total volatile nitrogen, responsible for the ammonia smell perceived in the ripening area and in the sausages. This is the first description of Levilactobacillus brevis predominance in spoiled goose sausage.

Shelf-life of sheep arrosticini packaged in protective atmosphere.

The aim of this study was to evaluate the shelf-life of pre-packaged sheep's arrosticini produced in a factory located in northern Italy. Samples were divided into two series and packaged in modified atmosphere with specific gas mixtures: conventional (C: 35% O2/15% CO2/50% N2) and experimental (E: 30% CO2/70% N2). All the samples were stored at 4°C for 10 days and subjected, after 5, 8 and 10 days (t5, t8, t10), to triplicate microbiological and chemical- physical (pH, total volatile basic nitrogen, thiobarbituric acid reactive substances) analyses. At the same time, the colorimetric analysis and a sensorial evaluation were carried out (pack tightness, presence of color or odor alterations), assigning a discrete score from 0 to 5. The samples showed initial total bacterial counts close to 5 Log CFU/g: these values gradually increased during storage, exceeding the threshold of 8 Log CFU/g in the C series; lower values were detected in the E series. A similar trend was highlighted for Enterobacteriaceae, with initial loads of about 3 Log CFU/g and an increase until t10, reaching values higher than 6 Log CFU/g in the C series and close to 5 Log CFU/g in the E series (P=0.002). E. coli also showed a similar trend, although with values approximately 1 Log lower than Enterobacteriaceae. Pseudomonas spp. showed initial counts close to 4.5 Log CFU/g, with a different increase in the C series (6.5 Log CFU/g at t10) and the E series (4.95 Log CFU/g) (P= 0.006). The higher growth in the C series was also observed for lactic acid bacteria, with an increase from 3 to 5 Log CFU/g (3.8 Log CFU/g in the E series P=0.016). The other microbiological parameters showed very low counts and, in most cases undetectable counts (<2 Log CFU/g) for the entire period considered. The initial values obtained from the measurement of the colorimetric indices were within the norm for this type of product: however, starting from t5, lower values of red index and lightness in the E series were measured, with an evident greying of meat surface. The results of the sensory evaluation indicated that the product showed optimal sensorial characteristics up to 8 days of shelf-life in the C series, while the use of an oxygenfree atmosphere, despite having a moderate inhibiting effect on the microbial populations, has led to an early modification of the product (5 days of storage), due to the presence of superficial greyish areas. The microbiological characteristics of arrosticini strictly depend on the hygienic conditions of slaughtering and production; even in optimal situations, the product is particularly perishable, and requires careful management of storage temperatures and times, to maintain its quality characteristics.

Microbial and Physico-Chemical Characterization of Cold Smoked Sea Bass (Dicentrarchus labrax), a New Product of Fishery.

The aim of this study was to investigate the microbial and physico-chemical characteristics of cold smoked sea bass (CSSB), a novel italian fish product. The microbiological analyses showed the presence of bacterial contamination from the raw material, the environment, and the production process. The microbial spoilage population was dominated by lactic acid bacteria (LAB) associated with Gram-negative fermenting bacteria, including Photobacterium phosphoreum and psychrotrophic Enterobacteriaceae. Brochotrix thermospacta and Aeromonas spp. were also present; in contrast, mould and yeast were not detected (<2 CFU/g). High levels (6-7 log CFU/g) of LAB and total bacteria count (TBC) were observed from day 45 of storage; however, their presence does not seem to have influenced the total volatile basic nitrogen (TVB-N), which always remained below 35 mg N/100 g. Consequently, the product is acceptable until day 60 of storage, considering that the malonaldehyde index (TBARS) was lower than 6.5 nmol/g. Pathogenic bacteria such as Salmonella spp. and Listeria monocytogenes were not detected. Currently, there is a growing demand for seafood due to its high quality and nutritional value. Cold smoked sea bass offers a source of macro- and micronutrients essential for the proper functioning of the human body. It is also rich in protein and omega-3 fatty acids. The WHO and FAO evaluated the benefits and risks and concluded that there is convincing evidence of health benefits from fish consumption, such as a reduction in the risk of heart failure and improved neurodevelopment in infants and young children when fish is consumed by the mother before and during pregnancy. The CSSB analysed in this study demonstrated to have health benefits due to long-chain omega-3 PUFAs and other nutrients, such as proteins, minerals, and vitamin D, which are sometimes difficult to obtain from other sources. The results show that CSSB has a high nutritional value and excellent microbial quality.

Compliance between Food and Feed Safety: Eight-Year Survey (2013-2021) of Aflatoxin M1 in Raw Milk and Aflatoxin B1 in Feed in Northern Italy.

Aflatoxins (AFs) are fungal metabolites that are found in feed and food. When ruminants eat feed contaminated with aflatoxin B1 (AFB1), it is metabolised and aflatoxin M1 (AFM1) is excreted in the milk. Aflatoxins can result in hepatotoxic, carcinogenic, and immunosuppressive effects. The European Union thus set a low threshold limit (50 ng/L) for presence of AFM1 in milk. This was in view of its possible presence also in dairy products and that quantification of these toxins is mandatory for milk suppliers. In the present study, a total of 95,882 samples of whole raw milk, collected in northern Italy between 2013 and 2021, were evaluated for presence of AFM1 using an ELISA (enzyme-linked immunosorbent assay) method. The study also evaluated the relationship between feed materials collected from the same farms in the same area during the same period (2013-2021) and milk contamination. Only 667 milk samples out of 95,882 samples analysed (0.7%) showed AFM1 values higher than the EU threshold limit of 50 ng/L. A total of 390 samples (0.4%) showed values between 40 and 50 ng/L, thus requiring corrective action despite not surpassing the regulatory threshold. Combining feed contamination and milk contamination data, some feedingstuffs seem to be more effective in defying potential carryover of AFs from feed to milk. Combining the results, it can be concluded that a robust monitoring system that covers both feed, with a special focus on high risk/sentinel matrices, and milk is essential to guarantee high quality and safety standards of dairy products.

Prevalence, Virulence Potential, and Growth in Cheese of Bacillus cereus Strains Isolated from Fresh and Short-Ripened Cheeses Sold on the Italian Market.

This study investigated B. cereus presence in 122 samples belonging to 34 typologies of fresh or short-ripened cheeses made from cow, sheep, goat, or buffalo pasteurized milk, and sold on the Italian market. B. cereus was isolated at a prevalence of 9.8%, with a marked variability among cheese categories, and at low counts (always below 2.26 Log CFU/g). Twelve isolates were identified by MALDI-TOF analysis and typified by RAPD PCR as belonging to different B. cereus strains. All the strains were tested for the production of hemolysin BL, phosphatidylcholine-specific phospholipase C, proteases, and biofilm formation, and for the presence of chromosomal toxin-encoding genes (sph, plcA, cytK, entFM, bcet, nheA, nheB, nheC). Overall, 92% of strains harbored bcet, 75% the three genes nheA, nheB, and nheC, as well as plcA and sph, 67% entFM, and 33% cytK. All strains showed biofilm-forming ability. A chemical-physical characterization of the cheeses was also performed to show their suitability as substrates for B. cereus growth, showing high heterogeneity in terms of pH, aw, salt content, and concentration of organic acids. Finally, the ability to support spore germination and vegetative cell growth of a selected cheese was investigated in spores-inoculated samples maintained at 10 °C and 15 °C, showing the inhibitory effect of low storage temperatures.

Packaging contaminants in former food products: Using Fourier Transform Infrared Spectroscopy to identify the remnants and the associated risks.

Food waste and feed-food competition can be reduced by replacing traditional feed ingredients such as cereals, with former food products (FFPs) in livestock diets. These foodstuffs, initially intended for human consumption, are recovered, mechanically unpacked, and then ground. Despite this simple and inexpensive treatment, packaging contaminants (remnants) are often unavoidable in the final product. To maximize the exploitation of FFPs and to minimize the associated risks, packaging remnants need to be quantified and characterized. This study tested the efficacy of the Fourier Transform Infrared Spectroscopy coupled with an optical microscope (µFT-IR) in identifying packaging remnants in 17 FFP samples collected in different geographical areas. After a visual sorting procedure, presumed packaging remnants were analyzed by µFT-IR. The results showed significant differences (p < 0.05) between the FFPs in terms of the total number of foreign particles found (plastics, cellulose and aluminum remnants, ranging from 4 to 19 particles per 20 g fresh matter), and also regarding the number of cellulose and aluminum particles. These data clearly demonstrate the need for sensitive instruments that can characterize the potential contaminants in the FFPs. This would then help to reduce the overestimation of undesirable contaminants typical of simple visual sorting, which is currently the most common method.

Ginger and parsley essential oils: chemical composition, antimicrobial activity, and evaluation of their application in cheese preservation.

Chemical composition and in vitro antimicrobial activity of parsley [Petroselinum crispum (Mill.) Fuss] and ginger (Zingiber officinale Roscoe) essential oils from store-bought parsley plants and ginger rhizomes were evaluated. A sensory analysis was performed on aged cheese slices treated with a mix of each essential oil and seed oil. Parsley essential oil was selected as the best compromise between sensory influence and antimicrobial activity and tested to evaluate its antifungal effects on cheese slices experimentally contaminated with Aspergillus flavus. Monoterpenes and α-zingiberene were the most abundant compounds in parsley and ginger essential oil, respectively. Both essential oils showed in vitro antimicrobial activity against different fungal species while only a bacterial strain (Enterococcus faecalis) was sensible to ginger essential oil. Only the cheese slices treated with parsley essential oil were appreciated by the panellists and its use has been effective in preventing the A. flavus growth in cheese.

Bacillus cereus in Dairy Products and Production Plants.

Spore-forming Bacillus cereus is a common contaminant of dairy products. As the microorganism is widespread in the environment, it can contaminate milk at the time of milking, but it can also reach the dairy products in each phase of production, storage and ripening. Milk pasteurization treatment is not effective in reducing contamination and can instead act as an activator of spore germination, and a potential associated risk still exists with the consumption of some processed foods. Prevalences and concentrations of B. cereus in milk and dairy products are extremely variable worldwide: in pasteurized milk, prevalences from 2% to 65.3% were reported, with concentrations of up to 3 × 105 cfu/g, whereas prevalences in cheeses ranged from 0 to 95%, with concentrations of up to 4.2 × 106 cfu/g. Bacillus cereus is also well known to produce biofilms, a serious concern for the dairy industry, with up to 90% of spores that are resistant to cleaning and are easily transferred. As the contamination of raw materials is not completely avoidable, and the application of decontamination treatments is only possible for some ingredients and is limited by both commercial and regulatory reasons, it is clear that the correct application of hygienic procedures is extremely important in order to avoid and manage the circulation of B. cereus along the dairy supply chain. Future developments in interventions must consider the synergic application of different mild technologies to prevent biofilm formation and to remove or inactivate the microorganism on the equipment.

Improving the Shelf-Life of Fish Burgers Made with a Mix of Sea Bass and Sea Bream Meat by Bioprotective Cultures.

Seafood products are one of the most perishable foods, and their shelf life is limited by enzymatic and microbial spoilage. Developing methods to extend the shelf life of fresh fish could reduce food waste in the fishery industry, retail stores, and private households. In recent decades, the application of lactic acid bacteria (LAB) as bioprotective cultures has become a promising tool. In this study, we evaluated the use of four starter cultures, previously selected for their properties as bioprotective agents, for sea bass and sea bream burgers biopreservation. Starter cultures impacted the microbial populations, biochemical parameters (pH, TVB-N), and sensory properties of fish burgers, during 10 days of storage at 4 °C and then 20 days at 8 °C in modified atmosphere packaging (MAP). Also, storage time influenced the microbial and physicochemical characteristics of all the tested samples, except for TVB-N values, which were significantly higher in the uninoculated burgers. The volatilome changed in the different treatments, and in particular, the samples supplemented with starter presented a profile that described their rapid growth and colonization, with the production of typical molecules derived from their metabolism. The addition of bioprotective cultures avoided bloating spoilage and improved the sensory parameters of the burgers. The shelf life of the fish burgers supplemented with starter cultures could be extended up to 12 days.

Characterization of a Bacillus cereus strain associated with a large feed-related outbreak of severe infection in pigs.

AIMS: Bacillus cereus is often responsible for foodborne diseases and both local and systemic infections in humans. Cases of infection in other mammals are rather rare. In this study, we report a B. cereus feed-related outbreak that caused the death of 6234 pigs in Italy. METHODS AND RESULTS: Massive doses of a Gram-positive, spore-forming bacterium were recovered from the animal feed, faeces of survived pigs and intestinal content of dead ones. The B. cereus MM1 strain was identified by MALDI-TOF MS and typified by RAPD-PCR. The isolate was tested for the production of PC-PLC, proteases, hemolysins and biofilm, for motility, as well as for the presence of genes encoding tissue-degrading enzymes and toxins. Antimicrobial resistance and pathogenicity in Galleria mellonella larvae were also investigated. Our results show that the isolated B. cereus strain is swimming-proficient, produces PC-PLC, proteases, hemolysins, biofilm and carries many virulence genes. The strain shows high pathogenicity in G. mellonella larvae. CONCLUSIONS: The isolated B. cereus strain demonstrates an aggressive profile of pathogenicity and virulence, being able to produce a wide range of determinants potentially hazardous to pigs' health. SIGNIFICANCE AND IMPACT OF STUDY: This study highlights the proficiency of B. cereus to behave as a devastating pathogen in swine if ingested at high doses and underlines that more stringent quality controls are needed for livestock feeds and supplements.

Evaluation of beef in purified sea water: microbiological and chemical-physical aspects.

In this study the influence of the maintenance of beef (Bavarian heifer meat submitted to dry aging for 1 month) in purified sea water was evaluated considering microbiological and physical-chemical parameters. The treated samples were perforated on their upper and lower surfaces, subsequently placed in sterile plastic containers, and covered with purified sea water while the control samples were wrapped in a plastic film; all the samples were stored at 2°C and sample analyses were performed on the day of receipt (t0) and after five (t5), seven (t7) and ten (t10) days of storage. The initial bacterial population was close to 6 log CFU/g, as expected in meat subjected to a long ageing. After 5 and 10 days of storage the treated samples showed significantly lower counts for most parameters (Total Bacterial Count, Enterobacteriaceae, Lactic Acid Bacteria and Pseudomonas spp.) if compared to the control samples. Halotolerant bacteria, yeasts and moulds showed no differences between the two series. During the test, the exposed surface of treated meat samples underwent a partial protein denaturation. Analyses show a moderate acidification of the meat during the first part of storage (from t0 to t5), followed by a substantial stabilization in the second part of the trial. The meat maintained in purified sea water acquired a significantly and constantly higher water retention due to the absorption of salt by the meat. No significant difference was detected in terms of tenderness between the two series.

Collection and analysis of post mortem inspection outcomes (liver lesions) from different cattle slaughtering plants located in Northern and Southern Italy.

The study evaluated the outcomes of cattle liver postmortem examination (64,766 animals) obtained from three slaughterhouses (two located in Lombardy, Northern Italy, and one in Puglia, Southern Italy) through the period 2016-2020. The frequency of specific lesions determining liver condemnation was calculated and the influence of several factors (animal age/category, geographical area, season, plant) was considered. A mean prevalence of 8% was observed, with a significant difference among the plants (range 6.4-12.8%). A significant difference was observed among the animal categories and age classes, with higher condemnation rates in animals aged more than 30 months (mainly cows). Steatosis was the most frequent lesion observed in cows (about half of the total), whereas liver abscesses were the most diffused in younger animals (half of the total in young bulls). Other frequently observed lesions were distomatosis and perihepatitis. A different pattern was observed between the two geographical areas, with a higher prevalence of steatosis in Lombardy (mainly intensive dairy farming), and of distomatosis in Puglia (animals mainly grazed on pasture). The season influenced the prevalence of lesions, and especially of steatosis (higher in summer). A different lesion prevalence was also observed between the two plants on similar animal populations, suggesting a difference in the notification and classification procedure among the plants. This study highlights the importance of a proper sharing procedure of the information obtained from the post mortem inspection in order to facilitate an optimal use of Food Chain Information and a useful feedback for farmers.

Growth potential of Listeria monocytogenes in veal tartare.

In the present study the growth potential of Listeria monocytogenes in veal tartare was evaluated. A challenge test was performed on three tartare batches at 8°C, aiming to evaluate the growth potential of the pathogen. The data indicated the absence of a significant growth (δ<0.5 log cfu/g) during the entire period. When considering intermediate sampling times, an increase of 0.56 log cfu/g was detected after five days of storage in one of the batches. Microflora of veal tartare was dominated by lactic acid bacteria, that increased gradually during the trial, reaching counts up to 7 Log CFU/g in two of the three batches considered. Spoilage bacteria were present (especially Pseudomonas spp., yeasts and Enterobacteriaceae) but in very low counts and with a limited increase during the period considered. Finally, daily maximum tolerable L. monocytogenes counts were calculated to highlight the maximum acceptable load to avoid the overcoming of the legal limit of 100 CFU/g: a total increase of 0.95 log cfu/g in 12 days of shelf-life was estimated, obtaining a "safety initial concentration" at t0 of 10 CFU/g of the pathogen.

Evolution of Food Safety Features and Volatile Profile in White Sturgeon Caviar Treated with Different Formulations of Salt and Preservatives during a Long-Term Storage Time.

Caviar is a semi-preserved fish preparation in which cold storage (around 0 °C) and packaging under anaerobic conditions are fundamental to guarantee adequate safety parameters. Consumers seem to prefer caviar prepared with food salt only, but according to the needs of the different distribution channels, some preservatives are used in order to prolong its shelf life and to allow less restrictive storage conditions. Traditionally, the most common preservative was sodium tetraborate (borax), a salt that contributes to the sensory profile of caviar. However, due to its toxicity, borax has been banned in many countries, and the current trend is to reduce or eliminate its use. In this study, we evaluated the evolution of food safety parameters (pH, water activity, microbiological parameters) and the volatile profile during 14 months of storage in caviar samples treated with three different preservatives: I. exclusively NaCl, II. a mixture of borax and NaCl, and III. a mixture of organic acids and salts. Microbial presence was studied by means of plate counts; volatile organic compounds were identified on the sample headspace by means of solid phase microextraction with gas-chromatography and mass spectrometry. Results showed relevant differences among the three treatments investigated, with salt samples characterized by the highest viable counts and the greatest presence of volatile products driven by oxidative and spoilage processes, mainly occurring toward lipid and amino acids. On the contrary, the mixture of organic acids and salts showed the best response during the entire storage period. Finally, the employment of a multiparametric statistic model allowed the identification of different clusters based on the time of ripening and the preservative treatments used.

Pseudomonas spp.: Are Food Grade Organic Acids Efficient against These Spoilage Microorganisms in Fresh Cheeses?

Psychrotolerant Pseudomonas spp. are among the most common spoilage agents in fresh, soft and semi-soft cheeses; therefore, hurdles inhibiting their growth are in strong demand by producers. This study aimed to establish Minimal Inhibiting Concentrations (MICs) of lactic and acetic acid towards P. fluorescens and to evaluate the efficacy of a cheese surface treatment with these two organic acids. MICs were determined in Brain Heart Infusion broth at 30 °C: the inhibition was achieved at a concentration of 49.96 mM and 44.40 mM of acetic and lactic acid, respectively. Two series of inhibition tests were performed on fresh "Primo sale" cheese, inoculated with P. brenneri MGM3, then dipped into different acid solutions (acetic acid: 49.96, 99.92 and 149.88 mM; lactic acid: 44.40, 88.80 and 133.20 mM) and stored at 6 °C. P. brenneri MGM3 were enumerated, including a control series. A significantly lower growth was revealed at the highest concentrations tested, both for acetic (p < 0.01) and lactic acid (p < 0.05) if compared to control samples. A conditioning of "Primo sale" surface with organic acid solutions could be a useful hurdle for Pseudomonas inhibition and shelf-life extension; it should be applied in combination with other mild interventions to fight spoilage and maintain the original product characteristics.

Evaluation of effect of chilling steps during slaughtering on the Campylobacter sp. counts on broiler carcasses.

Campylobacter spp. play an increasing role as foodborne pathogens, with poultry representing the main vehicle of infection, and control measures at the slaughterhouse have been implemented in the last years. In this study, 2 trials were performed, evaluating the effect of the chilling phases currently applied in an industrial slaughterhouse on the Campylobacter sp. contamination of broiler carcasses. In the first trial, neck skin samples were taken from 13 flocks before and after the on-chain air chilling and submitted to analysis of Campylobacter sp. count; in the second trial, 63 carcasses or cuts stored in the chilling room for variable times, with or without skin, were submitted to analysis of Campylobacter sp. count. A selection of 75 isolates was identified by PCR. All carcass skin samples taken from the first trial showed Campylobacter sp. counts higher than 0.7 log cfu/g. A wide variability in the counts (about 3 logs) was detected, showing a high correlation between the counts obtained before and after chilling. A slight decrease (P = 0.011) was observed after chilling (mean difference of about 0.3 log cfu/g), also if variability was observed among the flocks; the number of samples with high Campylobacter sp. counts (≥3 log cfu/g) was reduced (P = 0.010). In the second trial, low counts were generally detected (almost all lower than 3 log cfu/g). An evident decreasing trend was observed during storage, but the survival rate of Campylobacter on the cuts with skin was higher. All the isolates were identified as Campylobacter jejuni (72%) or Campylobacter coli. The data obtained were compared with the threshold limit set by EC Regulation 2073/2005, evidencing the impact of the sampling point on the counts. Our results highlighted the importance of applying a hurdle strategy including on-chain chilling and strict respect of the cold chain, allowing the food business operator to fulfill the process hygiene criteria and avoiding the delivery of highly contaminated meats.

Occurrence of Listeria spp. and Listeria monocytogenes Isolated from PDO Taleggio Production Plants.

The present study evaluated the presence of Listeria spp. and L. monocytogenes in four plants producing PDO Taleggio cheese. A total of 360 environmental samples were collected from different areas during production. The sampling points were identified as Food Contact Surfaces (FCS), transfer-Non Food Contact Surfaces (tr-NFCS), and non-transfer-NFCS (non-tr-NFCS). Fifty-nine ingredients/products were also analyzed. Listeria spp. was found in all the plants with a mean prevalence of 23.1%; plants that included a ripening area showed significantly higher prevalence if compared to the other plants. The positivity rate detected on FCS was moderate (~12%), but significantly lower if compared to NFCS (about 1/4 of the samples, p < 0.01). Among the FCS, higher prevalence was revealed on ripening equipment. Listeria spp. was never detected in the ingredients or products. A total of 125 Listeria spp. isolates were identified, mostly as L. innocua (almost 80%). L. monocytogenes was detected only from two FCS samples, in an area dedicated to the cutting of ripened blue cheeses; strain characterization by whole genome sequencing (WGS) evidenced a low virulence of the isolates. The results of the present study stress the importance of Listeria spp. management in the dairy plants producing PDO Taleggio and similar cheeses, mainly by the application of strict hygienic practices.

Identification and Pathogenic Potential of Bacillus cereus Strains Isolated from a Dairy Processing Plant Producing PDO Taleggio Cheese.

Low levels of contamination by Bacillus cereus at the cheese farm is essential for reducing any opportunity for growth prior consumption. In this study, B. cereus distribution in a plant producing Protected Designation of Origin Taleggio cheese was investigated and the virulence potential of the isolates was evaluated. Seventy-four samples were collected from Food and Non Food Contact Surfaces (FCS, NFCS), saline curd, and Taleggio. The eleven isolates were identified, typified, and clustered. Strains were tested for the production of hemolysins, hemolysin BL (HBL), phosphatidylcholine-specific phospholipase C (PC-PLC), proteases, and biofilm, and for the presence of chromosomal toxin-encoding genes (sph, plcA, cytK, entFM, bcet, entS, nheA, nheB, nheC). B. cereus was detected on NFCS, FCS, and curd, but not in Taleggio. The isolates were grouped into six clusters, and all produced PC-PLC, hemolysins, and proteases, and most of them HBL (66.7%). All the clusters harbored the nheA, sph, plcA, entFM, and cytK genes, and some also nheB (83.3%), nheC (66.7%), bcet (50.0%), and entS (66.7%). All strains showed biofilm-forming ability. Our data reveal possible contamination of production plants and cheese curd by potentially virulent B. cereus, but bacterial absence in Taleggio highlights the efficacy of a proper management of the production phases in assuring consumer's protection.