Artisanal raw milk cheeses are highly appreciated dairy products in Brazil and ensuring their microbiological safety has been a great need. This study reports the isolation and characterization of ...lactic acid bacteria (LAB) strains with anti-listerial activity, and their effects on Listeria monocytogenes during refrigerated shelf-life of soft Minas cheese and ripening of semi-hard Minas cheese. LAB strains (n = 891) isolated from Minas artisanal cheeses (n = 244) were assessed for anti-listerial activity by deferred antagonism assay at 37 °C and 7 °C. The treatments comprised the production of soft or semi-hard Minas cheeses using raw or pasteurized milk, and including the addition of selected LAB only Lactobacillus brevis 2-392, Lactobacillus plantarum 1-399 and 4 Enterococcus faecalis (1-37, 2-49, 2-388 and 1-400), L. monocytogenes only, selected LAB co-inoculated with L. monocytogenes, or without any added cultures. At 37 °C, 48.1% of LAB isolates showed anti-listerial capacity and 77.5% maintained activity at 7 °C. Selected LAB strains presented a bacteriostatic effect on L. monocytogenes in soft cheese. L. monocytogenes was inactivated during the ripening of semi-hard cheeses by the mix of LAB added. Times to attain a 4 log-reduction of L. monocytogenes were 15 and 21 days for semi-hard cheeses produced with raw and pasteurized milk, respectively. LAB with anti-listerial activity isolated from artisanal Minas cheeses can comprise an additional barrier to L. monocytogenes growth during the refrigerated storage of soft cheese and help shorten the ripening period of semi-hard cheeses aged at ambient temperature.
•Listeria concentration fell 4-log in 15 days in raw semi-hard cheese w/added LAB.•Listeria concentration fell 4-log in 21 days in pasteurized semi-hard cheese w/added LAB.•More than 70% of LAB isolated on MRS agar showed Listeria antagonism at 37 °C.•Added LAB significantly repressed but did not stop Listeria growth in soft cheese.•Correspondence analysis showed significant differences in regional LAB strains.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The fate of Listeria monocytogenes during ripening of artisanal Minas semi-hard cheese, as influenced by cheese intrinsic properties and by autochthonous (naturally present) or intentionally-added ...anti-listerial lactic acid bacteria (LAB) was modeled. Selected LAB strains with anti-listerial capacity were added or not to raw or pasteurized milk to prepare 4 cheese treatments. Counts of LAB and L. monocytogenes, pH, temperature and water activity were determined throughout cheese ripening (22 days, 22±1ᵒC). Different approaches were adopted to model the effect of LAB on L. monocytogenes: an independent approach using the Huang primary model to describe LAB growth and the linear decay model to describe pathogen inactivation; the Huang-Cardinal pH model using the effect of pH variation in a dynamic tertiary approach; and the Jameson-effect with Nmax tot model which simultaneously describes L. monocytogenes and LAB fate. L. monocytogenes inactivation occurred in both treatments with added LAB and inactivation was faster in raw milk cheese (−0.0260 h−1) vs. pasteurized milk cheese (−0.0182 h−1), as estimated by the linear decay model. Better goodness-of-fit was achieved for the cheeses without added LAB when the Huang primary model was used. A faster and great pH decline was detected for cheeses with added LAB, and the Huang-Cardinal pH model predicted higher pathogen growth rate in cheese produced with raw milk, but greater L. monocytogenes final concentration in pasteurized milk cheese. The Jameson-effect model with Nmax tot predicted that LAB suppressed pathogen growth in all treatments, except in the treatment with pasteurized milk and no LAB addition. The Huang-Cardinal pH model was more accurate in modeling L. monocytogenes kinetics as a function of pH changes than was the Jameson-effect model with Nmax tot as a function of LAB inhibitory effect based on the goodness-of-fit measures. The Jameson-effect model may however be a better competition model since it can more easily represent L. monocytogenes growth and death. This study presents crucial kinetic data on L. monocytogenes behavior in the presence of competing microbiota in Minas semi-hard cheese under dynamic conditions.
•Three different approaches were evaluated to predict L. monocytogenes behavior in semi-hard cheese.•All proposed models were capable of closely describing L. monocytogenes growth/death potential.•Huang-Cardinal pH present better fit quality than the Jameson-effect model.•The Huang-Cardinal model was not able to describe inactivation.•Addition of anti-listerial LAB results in a decrease in L. monocytogenes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study estimated the risk of listeriosis from Brazilian cheese consumption using quantitative microbial risk assessment (QMRA). Risks associated to consumption of two cheese types were assessed: ...artisanal ripened semi-hard cheese (produced with raw milk) and refrigerated fresh soft cheese (produced with pasteurized milk). The semi-hard cheese model predicted Listeria monocytogenes growth or decline during ripening, while the soft cheese model predicted pathogen growth during refrigerated storage. Semi-hard cheese modeling scenarios considered L. monocytogenes starting concentration from −2.4 to 6 log CFU/mL in raw milk and three ripening times (4, 22 and 60 days). Soft cheese modeling scenarios considered L. monocytogenes starting concentration from −2.4 to 4 log CFU/mL in milk. The inclusion of anti-listerial lactic acid bacteria (LAB) in cheeses was also examined. Risk of listeriosis due to consumption of soft cheese was 6000 and 190 times greater than that of semi-hard cheese, for general and vulnerable populations, respectively. Aging semi-hard cheese reduced risk, and risk was influenced by L. monocytogenes starting concentration. Aging cheese with inhibitory LAB for 22 days reduced risk over 4 million-fold when L. monocytogenes was assumed to be 6 log CFU/mL in raw milk. The inclusion of inhibitory LAB also reduced risk of listeriosis due to soft cheese consumption, but not as much as for semi-hard cheese. QMRA results predicted that consumption of contaminated cheeses can carry a high risk of listeriosis, especially for vulnerable populations. Scenario analyses indicated that aging of semi-hard cheese and inclusion of antimicrobial LAB mix in semi-hard and soft cheeses are effective risk mitigation measures.
•Vulnerable population presented high risk of listeriosis due to cheese consumption.•Soft cheese showed higher risk of listeriosis than semi-hard cheese.•Scenario analysis indicated that aging of semi-hard cheese reduced risk.•Lactic acid bacteria with anti-listerial activity are effective in risk reduction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This study compares dynamic tertiary and competition models for L. monocytogenes growth as a function of intrinsic properties of a traditional Brazilian soft cheese and the inhibitory effect of ...lactic acid bacteria (LAB) during refrigerated storage. Cheeses were prepared from raw or pasteurized milk with or without the addition of selected LAB with known anti-listerial activity. Cheeses were analyzed for LAB and L. monocytogenes counts, pH and water activity (aw) throughout cold storage. Two approaches were used to describe the effect of LAB on L. monocytogenes: a Huang-Cardinal model that considers the effect of pH and aw variation in a dynamic kinetic analysis framework; and microbial competition models, including Lotka-Volterra and Jameson-effect variants, describing the simultaneous growth of L. monocytogenes and LAB. The Jameson-effect with γ and the Lotka-Volterra models produced models with statistically significant coefficients that characterized the inhibitory effect of selected LAB on L. monocytogenes in Minas fresh cheese. The Huang-Cardinal model pH outperformed both competition models. Taking aw change into account did not improve the fit quality of the Huang-Cardinal pH model. These models for Minas soft cheese should be valuable for future microbial risk assessments for this culturally important traditional cheese.
•LAB with anti-listerial activity reduced the μopt and Ymax of L. monocytogenes.•Dynamic tertiary and competition models presented good fit quality.•Jameson-effect model with γ showed that LAB inhibited L. monocytogenes growth.•Lotka-Volterra model was significant for inhibition of L. monocytogenes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this study was to perform a meta-analysis of the effects of sanitizing treatments of fresh produce on Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. From 55 primary ...studies found to report on such effects, 40 were selected based on specific criteria, leading to more than 1,000 data on mean log reductions of these three bacterial pathogens impairing the safety of fresh produce. Data were partitioned to build three meta-analytical models that could allow the assessment of differences in mean log reductions among pathogens, fresh produce, and sanitizers. Moderating variables assessed in the meta-analytical models included type of fresh produce, type of sanitizer, concentration, and treatment time and temperature. Further, a proposal was done to classify the sanitizers according to bactericidal efficacy by means of a meta-analytical dendrogram. The results indicated that both time and temperature significantly affected the mean log reductions of the sanitizing treatment (P < 0.0001). In general, sanitizer treatments led to lower mean log reductions when applied to leafy greens (for example, 0.68 log reductions 0.00 to 1.37 achieved in lettuce) compared to other, nonleafy vegetables (for example, 3.04 mean log reductions 2.32 to 3.76 obtained for carrots). Among the pathogens, E. coli O157:H7 was more resistant to ozone (1.6 mean log reductions), while L. monocytogenes and Salmonella presented high resistance to organic acids, such as citric acid, acetic acid, and lactic acid (∼3.0 mean log reductions). With regard to the sanitizers, it has been found that slightly acidic electrolyzed water, acidified sodium chlorite, and the gaseous chlorine dioxide clustered together, indicating that they possessed the strongest bactericidal effect. The results reported seem to be an important achievement for advancing the global understanding of the effectiveness of sanitizers for microbial safety of fresh produce.
Today’s society demands healthy meat with a special emphasis on integrated animal husbandry combined with the concern for animal welfare. In this sense, the raising of lambs in an extensive system ...has been one of the most common practices, which results in meats with high nutritional value. However, both the production system and the diet play a fundamental role in the chemical composition of the meat, which has a direct impact on the content of volatile compounds. Thus, the aim of this study was to determine the effect of two production systems (intensive and extensive) on the chemical composition and volatile profile of lamb meat. Twenty-eight lambs of the Bordaleira-de-Entre-Douro-e-Minho (BEDM) sheep breed were raised for meat production under the intensive or extensive system and were fed with concentrate and pasture, respectively. All animals were carried out in the muscle longissimus thoracis et lumborum. Results evidenced that all the composition parameters were affected by the production system. Extensively-reared lambs produced meat with the highest fat and protein contents, while these animals had the lowest percentages of moisture and ash. Similarly, the total content of volatile compounds was affected (p < 0.05) by the production system and were higher in the meat of lambs reared extensively. Furthermore, the content of total acids, alcohols, aldehydes, esters, ethers, furans and sulfur compounds as well as most of the individual compounds were also affected (p < 0.05) by the production system, whereas total hydrocarbons and ketones were not affected (p > 0.05). As a general conclusion, the production system had very high influence not only in proximate composition but also in the volatile compounds.
The objective of this study was to investigate and summarize the levels of incidence of
spp.,
,
and
spp. in poultry meat commercialized in Europe. After systematic review, incidence data and study ...characteristics were extracted from 78 studies conducted in 21 European countries. Pooled prevalence values from 203 extracted observations were estimated from random-effects meta-analysis models adjusted by pathogen, poultry type, sampling stage, cold preservation type, meat cutting type and packaging status. The results suggest that
is the main pathogen detected in poultry meat (38.5%; 95% CI: 25.4⁻53.4), followed by
spp. (33.3%; 95% CI: 22.3⁻46.4%), while
and
spp. present lower prevalence (19.3%; 95% CI: 14.4⁻25.3% and 7.10%; 95% CI: 4.60⁻10.8%, respectively). Despite the differences in prevalence, all pathogens were found in chicken and other poultry meats, at both end-processing step and retail level, in packed and unpacked products and in several meat cutting types. Prevalence data on cold preservation products also revealed that chilling and freezing can reduce the proliferation of pathogens but might not be able to inactivate them. The results of this meta-analysis highlight that further risk management strategies are needed to reduce pathogen incidence in poultry meat throughout the entire food chain across Europe, in particular for
and
spp.
A review of the published quantitative risk assessment (QRA) models of
in dairy products was undertaken in order to identify and appraise the relative effectiveness of control measures and ...intervention strategies implemented at primary production, processing, retail, and consumer practices. A systematic literature search retrieved 18 QRA models, most of them (9) investigated raw and pasteurized milk cheeses, with the majority covering long supply chains (4 farm-to-table and 3 processing-to-table scopes). On-farm contamination sources, either from shedding animals or from the broad environment, have been demonstrated by different QRA models to impact the risk of listeriosis, in particular for raw milk cheeses. Through scenarios and sensitivity analysis, QRA models demonstrated the importance of the modeled growth rate and lag phase duration and showed that the risk contribution of consumers' practices is greater than in retail conditions. Storage temperature was proven to be more determinant of the final risk than storage time. Despite the pathogen's known ability to reside in damp spots or niches, re-contamination and/or cross-contamination were modeled in only two QRA studies. Future QRA models in dairy products should entail the full farm-to-table scope, should represent cross-contamination and the use of novel technologies, and should estimate
growth more accurately by means of better-informed kinetic parameters and realistic time-temperature trajectories.
•Lamb meat quality depends on the combined effect breed × production system.•BEDM and Gallega reared under extensive conditions had high amounts of n-3 PUFA.•Lambs reared under extensive system had ...the highest tocopherol and cholesterol levels.•Lambs reared under extensive system had the best n-6/n-3 ratio and high SFA content.•The production system and diet had great influence in meat quality.
This study aimed to compare lamb meat composition from five Iberian breeds raised in their typical rearing systems and to reveal trends in compositional meat attributes due to breed or production system. The meat quality of 153 animals was analysed. The combined effect of breed × production system produced significant differences in lamb meat quality. Meat from the extensively-reared Bordaleira-de-Entre-Douro-e-Minho (BEDM) and Gallega breeds had elevated amounts of n-3 PUFAs, tocopherol content and favourable n-6/n-3 ratio. Meat from lambs grown under extensive and semi-extensive systems presented higher content of conjugated linoleic acid than the two breeds reared intensively. The meat of commercial breed (INRA401) was characterised by higher content of protein and MUFAs and lower atherogenic potential than the breeds reared in extensive and semi-extensive systems. Principal component analysis demonstrated that meat from extensively raised lambs was associated to higher SFA, CLA, α-tocopherol, n-3, atherogenic index and cholesterol content, but lower intramuscular fat and retinol content, MUFA and n-6/n-3.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Lamb meat quality of three Italian and German breeds was evaluated.•Meat of lambs reared in extensive system had the lowest SFA content.•Meat of lambs reared in extensive system had the highest n-3 ...PUFA content.•Meat from the Italian Sambucana lambs presented the lowest cholesterol content.•Meat from the three breeds was of high quality with low fat content.
The aim of this study was to evaluate and compare the quality characteristics, chemical composition and lipid profile of lamb meat from Italian (Biellese and Sambucana) and German (Texel-Merino-Blackhead-Charollais TMBC) breeds reared in extensive and semi-extensive production systems. Meat samples from 89 animals were analysed. The meat of the lambs from semi-intensively reared Biellese, and extensively reared Sambucana and TMBC breeds produced lean meat, with slightly higher intramuscular fat content in TMBC. The latter also produced meat of darker colour (P < 0.05) and higher protein content (P < 0.05). The meat of Sambucana lambs presented the lowest total cholesterol content (P < 0.05). The fatty acid profile of the meat showed a clear advantage of both extensively reared breeds, which had substantially lower proportion of saturated but higher of polyunsaturated fatty acids, particularly n-3 (P < 0.05). The beneficial effect of the extensive rearing conditions was associated with lower n-6/n3 ratio, and atherogenic and thrombogenic indices, thereby suggesting that production system can be used successfully to modify the fatty acid profile to achieve a positive effect for the human health.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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