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1.
Int J Food Microbiol ; 313: 108379, 2020 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-31675541

RESUMEN

Lactobacillus algidus is a meat spoilage bacterium often dominating the bacterial communities on chilled, packaged meat. Yet, L. algidus strains are rarely recovered from meat, and only few studies have focused on this species. The main reason limiting detailed studies on L. algidus is related to its poor growth on the media routinely used for culturing food spoilage bacteria. Thus, our study sought to develop reliable culture media for L. algidus to enable its recovery from meat, and to allow subculturing and phenotypic analyses of the strains. We assessed the growth of meat-derived L. algidus strains on common culture media and their modifications, and explored the suitability of potential media for the recovery of L. algidus from meat. Moreover, we determined whether 12 meat-derived L. algidus strains selected from our culture collection produce biogenic amines that may compromise safety or quality of meat, and finally, sequenced de novo and annotated the genomes of two meat-derived L. algidus strains to uncover genes and metabolic pathways relevant for phenotypic traits observed. MRS agar supplemented with complex substances (peptone, meat and yeast extract, liver digest) supported the growth of L. algidus, and allowed the recovery of new L. algidus isolates from meat. However, most strains grew poorly on standard MRS agar and on general-purpose media. In MRS broth, most strains grew well but a subset of strains required supplementation of MRS broth with additional cysteine. Supplementation of MRS broth with catalase allowed growth in aerated cultures suggesting that the strains produced hydrogen peroxide when grown aerobically. The strains tested (n = 12) produced ornithine from arginine and putrescine from agmatine, and two strains produced tyramine from tyrosine. Our findings reveal that L. algidus populations are underestimated if routine culture protocols are applied, and prompt concerns that L. algidus may generate tyramine or putrescine in meat or fermented meat products.


Asunto(s)
Lactobacillus/crecimiento & desarrollo , Productos de la Carne/microbiología , Animales , Aminas Biogénicas/análisis , Aminas Biogénicas/metabolismo , Bovinos , Medios de Cultivo/metabolismo , Fermentación , Lactobacillus/metabolismo , Productos de la Carne/análisis , Putrescina/análisis , Putrescina/metabolismo , Porcinos
2.
Int J Food Microbiol ; 312: 108358, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31655356

RESUMEN

Meat products are commonly regarded as one of the main sources of human listeriosis caused by Listeria monocytogenes. The objective of this study was to estimate the prevalence of L. monocytogenes in a range of meat products from 24 different Chinese regions by using meta-analysis of literature data and a novel sensitivity analysis approach. A total of 112 publications from five databases, published between 1 January 2007 and 31 December 2017, were systematically selected for relevance and covered meat products sampled between 2000 and 2016. Estimated by the random-effects model, the pooled prevalence of L. monocytogenes was 8.5% (95% CI: 7.1%-10.3%) in raw meats and 3.2% (95% CI: 2.7%-3.9%) in ready-to-eat (RTE) meats. The prevalence differed from high to low among raw meats including prefabricated raw meats 12.6% (95% CI: 6.9%-21.7%), fresh pork 11.4% (95% CI: 8.6%-14.9%), fresh beef 9.1% (95% CI: 6.3%-13.0%), fresh poultry 7.2% (95% CI:4.9%-10.4%), frozen raw meats 7.2% (95% CI: 5.7%-9.0%), and fresh mutton 5.4% (95% CI: 2.5%-11.0%). A higher L. monocytogenes prevalence level was shown in the meat products from central and northeastern China provincial regions. The entropy-based sensitivity analysis utilized in the meta-analysis indicated that the sampling period and location were two critical factors influencing the prevalence level of L. monocytogenes in meat products. A better understanding of differences in prevalence levels per geographic region and between meat product sources may allow the competent authorities, industry, and other relevant stakeholders to tailor their interventions to control the occurrence of L. monocytogenes in meat products effectively.


Asunto(s)
Contaminación de Alimentos/análisis , Microbiología de Alimentos , Listeria monocytogenes/aislamiento & purificación , Productos de la Carne/microbiología , Aves de Corral/microbiología , Animales , Bovinos , China , Humanos , Listeriosis/epidemiología , Prevalencia , Ovinos , Porcinos
3.
Food Microbiol ; 85: 103285, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500704

RESUMEN

The objective of this study was to determine the kinetic parameters and apply Markov Chain Monte Carlo (MCMC) simulation to predict the growth of Clostridium perfringens from spores in cooked ground chicken meat during dynamic cooling. Inoculated samples were exposed to various cooling conditions to observe dynamic growth. A combination of 4 cooling profiles was used in one-step inverse analysis with the Baranyi model as the primary model and the cardinal parameters model as the secondary model. Six kinetic parameters of the Baranyi model and the cardinal parameters model, including Q0, Ymax, µopt, Tmin, Topt, and Tmax, were estimated. The estimated Tmin, Topt, and Tmax were 14.8, 42.9, and 50.5 °C, respectively, with a µopt of 5.25 h-1 and maximum cell density of 8.4 log CFU/g. Correlation analysis showed that both Q0 and Ymax are weakly correlated to other parameters, while the remaining parameters are mostly mildly to strongly correlated with each other. Although it may be difficult to estimate highly correlated parameters using a single temperature profile, one-step analysis with multiple different temperature profiles helped estimate them successfully. The estimated parameters were used as the prior information to construct the posterior distribution for Bayesian analysis. MCMC simulation was used to predict the bacterial growth using different dynamic temperature profiles for validation of the accuracy of the predictive models. The MCMC simulation results showed that the Bayesian analysis produced more accurate predictions of bacterial growth during cooling than the deterministic method. With Bayesian analysis, the root-mean-square-error (RMSE) of prediction was only 0.1 log CFU/g with all residual errors within ±0.25 log CFU/g. Therefore, Bayesian analysis is recommended for predicting the growth of C. perfringens in cooked meat during cooling.


Asunto(s)
Clostridium perfringens/crecimiento & desarrollo , Culinaria , Manipulación de Alimentos , Productos de la Carne/microbiología , Temperatura Ambiental , Animales , Teorema de Bayes , Pollos , Recuento de Colonia Microbiana , Simulación por Computador , Cinética , Cadenas de Markov , Modelos Biológicos , Método de Montecarlo , Esporas Bacterianas/crecimiento & desarrollo
4.
Food Microbiol ; 85: 103280, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500706

RESUMEN

Listeria monocytogenes causes severe diseases in humans, including febrile gastroenteritis and systemic infections that has a high mortality despite antibiotic treatment. This pathogen may cause massive outbreaks associated to the consumption of contaminated food products, which highlight its importance in public health. In the last decade, L. monocytogenes has emerged as a foodborne pathogen of major importance in Chile. A previous work showed that in Chile during 2008 and 2009, L. monocytogenes serotypes 1/2a, 1/2b and 4b were the most frequently identified in food and clinical strains. Here we report the molecular characterization of L. monocytogenes strains isolated from 2008 to 2017 in the country. Our results indicate that serotypes 1/2a, 1/2b and 4b continue to be the most commonly found in food products. In addition, we identify persistent and widespread PFGE subtypes. This study reports ten years of epidemiological surveillance ofL. monocytogenes in Chile.


Asunto(s)
Monitoreo Epidemiológico , Microbiología de Alimentos , Enfermedades Transmitidas por los Alimentos/epidemiología , Listeria monocytogenes/genética , Listeriosis/epidemiología , Chile/epidemiología , Recuento de Colonia Microbiana , ADN Bacteriano/genética , Brotes de Enfermedades , Enfermedades Transmitidas por los Alimentos/microbiología , Gastroenteritis/epidemiología , Gastroenteritis/microbiología , Variación Genética , Humanos , Listeria monocytogenes/patogenicidad , Productos de la Carne/microbiología , Epidemiología Molecular , Salud Pública , Serogrupo , Serotipificación , Factores de Virulencia/genética
5.
Syst Appl Microbiol ; 42(6): 126023, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31668878

RESUMEN

Microbiota analysis of blown pack spoiled salami revealed five distinguishable Lactobacillus isolates we could not assign to a known species. Two of the isolates (TMW 1.2172T and TMW 1.1920) are rod-shaped, whilst three isolates (TMW 1.2098T, TMW 1.2118 and TMW 1.2188) appear coccus shaped or as short rods. All isolates are Gram-stain positive, facultative anaerobic, catalase and oxidase negative, non-motile and non-sporulating. Phylogenetic analysis of the 16S rRNA, dnaK, pheS and rpoA gene sequences revealed two distinct lineages within the genus Lactobacillus (L.). The isolates are members of the Lactobacillus alimentarius group with Lactobacillus ginsenosidimutans DSM 24154T (99.4% 16S similarity), Lactobacillus versmoldensis DSM 14857T (97.9%) and Lactobacillus furfuricola DSM 27174T (97.7%) as phylogenetic closest related species and L. alimentarius DSM 20249T (97.7%) and Lactobacillus paralimentarius DSM 13961T (97.5%) as closest relatives, respectively. Average Nucleotide Identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the isolates and their close related type strains are lower than 80% and 25%, respectively. For both designated type strains, the peptidoglycan type is A4α l-Lys-d-Asp and the major fatty acids are C16:0, C18:1ω9c and summed feature 7. Based on phylogenetic, phenotypic and chemotaxonomic analysis we demonstrated that the investigated isolates belong to two novel Lactobacillus species for which we propose the names Lactobacillus salsicarnum with the type strain TMW 1.2098T=DSM 109451T=LMG 31401Tand Lactobacillus halodurans with the type strain TMW 1.2172T=DSM 109452T=LMG 31402T.


Asunto(s)
/microbiología , Microbiología de Alimentos , Lactobacillus/clasificación , Productos de la Carne/microbiología , Filogenia , Animales , Composición de Base , Ácidos Grasos/análisis , Genes Bacterianos/genética , Genoma Bacteriano/genética , Lactobacillus/química , Lactobacillus/genética , Lactobacillus/ultraestructura , Hibridación de Ácido Nucleico , Peptidoglicano/análisis , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Especificidad de la Especie , Porcinos
6.
Lett Appl Microbiol ; 69(6): 392-398, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31562639

RESUMEN

Four cases of listeriosis in a hospital (A) in New Zealand were identified in 2012. Pulsed-field gel electrophoresis (PFGE) used at the time identified four pulsotypes amongst the clinical isolates. Two of the pulsotypes matched to Listeria monocytogenes isolates obtained from ready-to-eat (RTE) meat samples from a RTE producer tested during a nationwide microbiological survey the month prior. The outbreak investigation confirmed that the RTE producer had supplied product to the hospital and additional testing confirmed the presence of L.  monocytogenes in RTE meats from the hospital kitchen. Two further listeriosis cases presented in another hospital (B) with one clinical isolate identified as the same pulsotype as identified for one case in hospital A, but the epidemiology information concluded that the clinical cases from hospital B were not linked to the outbreak. Retrospective whole-genome sequencing confirmed that epidemiologically linked isolates belonging to three different genotypes for clinical cases from hospital A and RTE meats samples from the hospital kitchen differed by 0-1 core-genome locus or single nucleotide polymorphisms (SNP). The use of core-genome multilocus sequence typing and SNP analysis provided a greater degree of discrimination between isolates compared to PFGE. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes a listeriosis outbreak associated with a hospital in New Zealand and attributed to contaminated ready-to-eat (RTE) meat supplied to the hospital by a single producer. Retrospective whole-genome sequence analysis of outbreak isolates was found to provide a greater degree of discrimination between isolates compared to pulsed-field gel electrophoresis and supported the conclusions made at the time of the outbreak. The multiple genotypes identified from clinical cases and the RTE meats obtained during the outbreak highlight the importance of epidemiological concordance alongside genotyping.


Asunto(s)
Infección Hospitalaria/microbiología , Listeria monocytogenes/genética , Listeriosis/epidemiología , Productos de la Carne/microbiología , Carne/microbiología , Brotes de Enfermedades , Electroforesis en Gel de Campo Pulsado , Microbiología de Alimentos , Genoma Bacteriano/genética , Genotipo , Humanos , Listeria monocytogenes/clasificación , Listeria monocytogenes/aislamiento & purificación , Listeriosis/microbiología , Tipificación de Secuencias Multilocus , Nueva Zelanda/epidemiología , Polimorfismo de Nucleótido Simple/genética , Estudios Retrospectivos , Secuenciación Completa del Genoma
7.
J Food Sci ; 84(10): 2932-2943, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31524954

RESUMEN

The microbiota of traditional dry-cured sausages and industrial environment was assessed to characterize the diversity of coagulase-negative staphylococci (CNS), and establish potential relationships with hygiene level or technological characteristics. Eight processing units from South Portugal were audited according to a checklist of requirements. Environmental and products' samples at different production stages were evaluated regarding hygiene and safety criteria. CNS were recovered, characterized, and their potential use as starters evaluated. Low genetic diversity was observed for Staphylococcus xylosus, whereas Staphylococcus equorum showed diverse genetic profiles. Staphylococcus xylosus predominated in products with a long period of cold smoking, Staphylococcus saprophyticus in products with a long period of hot smoking, Staphylococcus epidermidis in products with a short period of cold smoking, and S. equorum in nonsmoked products. Most S. xylosus were resistant to tetracycline, whereas S. equorum were susceptible. Antibioresistance restricted the selection of starters due to safety recommendations. PRACTICAL APPLICATION: The present manuscript highlighted a few staphylococci strains that could potentially be used as starter cultures in fermented meat products. These selected strains do not show resistance to antimicrobials, exhibit adequate technological features, and are well adapted to the industrial environments of meat processing industries using different processing technologies. Therefore, the selected strains ready to be used in the manufacturing of traditional fermented meat products to ensure safety, standardize product properties, and shorten ripening.


Asunto(s)
Biodiversidad , Productos de la Carne/microbiología , Staphylococcus/aislamiento & purificación , Animales , Antibacterianos/farmacología , Fermentación , Manipulación de Alimentos/instrumentación , Microbiología de Alimentos , Filogenia , Portugal , Staphylococcus/clasificación , Staphylococcus/efectos de los fármacos , Staphylococcus/genética , Porcinos
8.
Can J Microbiol ; 65(12): 913-921, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31491332

RESUMEN

This study reports the use of reverse transcription - loop-mediated isothermal amplification (RT-LAMP) to detect Listeria monocytogenes in meat. The assay was designed to target the iap gene of L. monocytogenes, to which four primers, recognizing six distinct iap sites, were designed. We optimized the RT-LAMP conditions and established the following optimal systems: 60 min, 63 °C, 2.0 mmol/L MgSO4, 1.0 mol/L betaine, 2.0 mmol/L dNTPs, 320 U/mL Bst DNA polymerase, 0.4 µmol/L outer primers, and 0.8 µmol/L inner primers. The RT-LAMP amplification products were identified by a visible white Mg2P2O7 precipitate or electrophoresis on a 2% agarose gel. RT-LAMP has a sensitivity of 7.3 × 101 CFU/mL, which is 2-fold higher than that of LAMP. When commercially available raw meat samples (including beef, pork, mutton, and rabbit) were analyzed simultaneously with RT-LAMP and the Chinese National Standard GB 4789.30-2016, their abilities to detect L. monocytogenes were the same. Samples containing L. monocytogenes killed by 15 psi at 121 °C for 15 min were used to confirm the specificity of RT-LAMP for live microorganisms. Thus, we used RT-LAMP to efficiently detect L. monocytogenes in meat products.


Asunto(s)
Microbiología de Alimentos/métodos , Listeria monocytogenes/aislamiento & purificación , Productos de la Carne/microbiología , Técnicas de Amplificación de Ácido Nucleico , Animales , Proteínas Bacterianas/genética , Lipoproteínas/genética , Listeria monocytogenes/genética , Carne/microbiología , Sensibilidad y Especificidad
9.
J S Afr Vet Assoc ; 90(0): e1-e8, 2019 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-31478731

RESUMEN

Staphylococcus aureus, including methicillin-resistant strains, has been detected in food products of animal origin globally. Limited data have been reported on the factors contributing to antibiotic resistance of food-borne pathogens in South Africa. The primary aim of this study was to determine the prevalence of S. aureus, including antibiotic-resistant strains, in poultry meat products as well as the evaluation of potential risk factors for contamination of poultry meat products with antibiotic-resistant S. aureus isolates. A cross-sectional investigation was conducted in municipalities located across the nine provinces of South Africa, which included abattoirs, meat processing facilities, retail outlets and cold stores at the major ports of entry into South Africa. Staphylococcus aureus isolates obtained from various poultry meat products were tested for susceptibility to 14 antibiotic compounds representing 10 antibiotic classes using the Kirby-Bauer disc diffusion method. Potential risk factors were evaluated using a logistic regression model. Of the 311 samples tested, 34.1% (n = 106) were positive for S. aureus (95% confidence interval [CI], 28.9% - 39.7%). Seventy-two of the 106 isolates were randomly selected for antibiotic sensitivity testing. Twenty-one per cent (n = 15) of the isolates selected for sensitivity testing were methicillin-resistant strains (95% CI, 12.2% - 32.0%). Multi-drug resistance was detected in 22.2% (n = 16) of these isolates tested (95% CI, 13.3% - 33.6%). Origin of the product (p = 0.160), type of meat product (p = 0.962), type of facility (p = 0.115) and facility hygiene practices (p = 0.484) were not significantly associated with contamination of poultry meat products with methicillin-resistant strains. The study provides baseline data for further studies on antibiotic resistance risk assessments for food-borne pathogens, including S. aureus, which should guide the implementation plans of the South African National Antimicrobial Resistance Strategy Framework, 2017-2024.


Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Productos de la Carne/microbiología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Aves de Corral , Staphylococcus aureus/efectos de los fármacos , Animales , Estudios Transversales , Microbiología de Alimentos , Pruebas de Sensibilidad Microbiana , Enfermedades de las Aves de Corral/tratamiento farmacológico , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/microbiología , Factores de Riesgo , Sudáfrica/epidemiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/aislamiento & purificación
10.
Int J Food Microbiol ; 309: 108312, 2019 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-31499265

RESUMEN

The characteristics and quality of home-made dry cured sausages can be recognized and associated with the region of origin. The characteristics of this type of sausages result from the superficial mycobiota that spontaneously colonizes the products. The aim of this study was to identify the house mycobiota associated with home-made dry cured sausages from different localities of Argentina and characterize the populations of Penicillium nalgiovense present by morphological and biochemical markers. To this end, 79 samples were collected from 10 localities of three main producing regions (Buenos Aires, Córdoba and La Pampa provinces). A total of 196 isolates belonging to six genera and 17 species were obtained. The predominant genus was Penicillium (134 of the isolates) and the predominant species was P. nalgiovense (108 isolates). The isoenzyme patterns of α-esterase (α-EST; EC 3.1.1.1) and Malate dehydrogenase NADP+(MDHP; EC 1.1.1.40) were characterized in 48 of these isolates (ten from Colonia Caroya, ten from Oncativo, ten from Tandil, nine from Mercedes and nine from La Pampa). A total of 26 bands were observed: 17 for α-EST and 9 for MDHP. α-EST was the most polymorphic isoenzyme, whereas MDPH presented no polymorphism. The results were subjected to numerical analysis. Cluster analysis revealed the formation of two groups: Group I formed by 24 isolates from Córdoba and Buenos Aires provinces and Group II with 24 isolates from La Pampa and Buenos Aires province. These data suggest the existence of morphological and biochemical variations among P. nalgiovense populations with different geographical origin.


Asunto(s)
Productos de la Carne/microbiología , Penicillium/clasificación , Penicillium/aislamiento & purificación , Argentina , Esterasas/genética , Fermentación , Contaminación de Alimentos/análisis , Malato Deshidrogenasa/genética , Penicillium/genética
11.
Int J Food Microbiol ; 307: 108286, 2019 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-31400632

RESUMEN

This study was designed to explore the temperature effects on bacterial communities and metabolites, as well as their relationships during the fermentation of sour meat, a traditional fermented meat product in the ethnic minority regions of China. Results showed that reduction of pH and increase of lactic acid and free amino acid contents occurred (p < 0.05) as the fermentation temperature and time increased, and the tendency was more apparent at higher temperature. During the fermentation, Lactobacillus gradually replaced other genera, and higher the temperature, more rapid was the process. Both the number and amount of volatile organic compounds increased at higher temperatures. Hexanal, benzaldehyde, nonanal, (E,E)-2,4-decadienal, 1-octen-3-ol and octanal were identified as the key volatile organic compounds produced by Lactobacillus in sour meat as main contributors to odor as confirmed by variable importance in the projection analysis. Redundancy analysis and Pearson correlation showed positive correlation between Lactobacillus and desired product characteristics, such as higher content of lactic acid, free amino acids, volatile organic compounds, and lower pH and water activity values, which may represent a better quality and longer shelf life after fermentation at higher temperature. Therefore fermentation at 20 °C and 25 °C are proposed as optimum temperatures for sour meat production.


Asunto(s)
Fermentación , Microbiología de Alimentos , Productos de la Carne/análisis , Productos de la Carne/microbiología , Microbiota/fisiología , Temperatura Ambiental , Aminoácidos/análisis , China/etnología , Ácido Láctico/metabolismo , Lactobacillus/crecimiento & desarrollo , Lactobacillus/metabolismo , Microbiota/genética , Odorantes/análisis , Compuestos Orgánicos Volátiles/análisis
12.
J Appl Microbiol ; 127(6): 1751-1758, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31448854

RESUMEN

AIMS: The purpose of this experiment was to study the bacterial diversity and predominance of spoilage bacteria in chicken skin at different thermal treatment temperatures (60, 70, 80, 90, 100, 110, 120°C). METHOD AND RESULTS: Bacteria in chicken skin was collected, then propidium monoazide treatment to remove the DNA of dead cell, total DNA was extracted by Tiandz Bacterial DNA Kit, and investigated by high-throughput sequencing of the v3/v4 regions of the 16S rDNA gene. A total of 796 008 high-quality bacterial sequences were obtained for assessing the microbial diversity of chicken skin from seven thermal treatment group and control group. The results showed that the bacterial diversity in chicken skin at 90°C was lowest. And Acinetobacter (25·88%), Clostridium (20·70%), Bacteroides (13·93%) and Myroides (13·13%) were the main flora at 25°C; The Clostridium was dominant genus of the samples heat-treated by 60, 70, 80 and 90°C, the proportion of this genus were up to 64·86, 77·42, 52·22 and 87·30% respectively. The Bacillus was the main flora of the samples heat-treated by 100, 110 and 120°C, and the relative percentages were 39·44, 79·61 and 45·96% respectively. In addition, high-temperature-resistant Serratia was found in chicken skin. CONCLUSIONS: The study revealed that the relationship between thermal treatment temperature and bacterial diversity and dominant spoilage bacteria in chicken skin, which had a strong guiding significance for the control and prediction of micro-organisms in foods. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this paper could provide a theoretical basis for meat products containing chicken skin, including the safe use of chicken skin, determination of sterilization process parameters and selection of preservatives for compounding, which has strong practicality in China.


Asunto(s)
Bacterias/clasificación , Bacterias/aislamiento & purificación , Biodiversidad , Calor , Productos de la Carne/microbiología , Piel/microbiología , Animales , Azidas/química , Bacterias/genética , Pollos , ADN Bacteriano/química , ADN Bacteriano/genética , Propidio/análogos & derivados , Propidio/química , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN
13.
Int J Food Microbiol ; 308: 108308, 2019 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-31466020

RESUMEN

Cattle are a reservoir for enterohemorrhagic Escherichia coli (EHEC), and ground beef is a major vehicle for human infection with EHEC. Heat resistance of E. coli, including EHEC, is impacted by NaCl and other additives. This study aimed to evaluate the effect of NaCl and other additives on the heat resistance of E. coli in beef patties. E. coli AW1.7ΔpHR1(pLHR) with the locus of heat resistance (LHR), E. coli AW1.7ΔpHR1(pRK767) without LHR, or a 5-strain cocktail of EHEC were inoculated (107-108 CFU/g) into ground beef (15% fat) with NaCl (0-3%), marinade, carvacrol (0.1%), potassium lactate (3%) or chitosan (0.1%) following different protocols. Patties were grilled immediately, or stored in sterile bags for two days at 4 °C prior to grilling to a core temperature of 71 °C. Cell counts of LHR-positive E. coli AW1.7ΔpHR1(pLHR) were higher than that of the isogenic LHR-negative E. coli AW1.7ΔpHR1(pRK767) by >3 log10 (CFU/g) after cooking. Addition of 3% NaCl increased survival of E. coli AW1.7ΔpHR1(pRK767) and the EHEC cocktail while cell counts of the heat resistant strains were not changed. A protective effect of NaCl was not observed with E. coli AW1.7ΔpHR1(pRK767) or EHEC if cells of E. coli were cooled to 4 °C prior to mixing with cold meat and NaCl, indicating that the response of E. coli to osmotic shock contributes to this effect. Chitosan enhanced the thermal destruction of LHR-positive E. coli AW1.7ΔpHR1(pLHR) in ground beef stored at 4 °C for 2 days, while marinade, carvacrol, or potassium lactate had no such effect, indicating that chitosan can be characterized as an effective hurdle concept to reduce the potential risk of LHR-positive pathogen to meat safety.


Asunto(s)
Quitosano/farmacología , Escherichia coli Enterohemorrágica/efectos de los fármacos , Productos de la Carne/microbiología , Carne/microbiología , Cloruro de Sodio/farmacología , Animales , Bovinos , Recuento de Colonia Microbiana , Culinaria/métodos , Escherichia coli Enterohemorrágica/fisiología , Calor , Humanos , Monoterpenos/farmacología
14.
Meat Sci ; 158: 107912, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31421517

RESUMEN

The performance of mechanically deboned chicken meat protein (MDCM-P) coatings containing thyme (TEO) or clove essential oils (CEO) was investigated to improve the storage quality of heat treated sucuks during 45 days of storage at 4 °C. The sucuk slices were divided to 4 groups as uncoated, coated with MDCM-P solution, coated with MDCM-P solution containing 1.5% TEO and MDCM-P solution containing 1.5% CEO. Physical, chemical and microbial properties of sucuk samples were analyzed on 0, 15, 30 and 45 days of storage. Results indicated that the weight loss, pH, thiobarbituric acid reactive subtances, total viable and psychrotrophic bacteria counts increased, while a* and b* values and water activity decreased with storage time (p < .05). In all analysis periods, these changes were slowed down with coating applications containing essential oils, but the slowest changes were observed in coated sucuks with MDCM-P solution containing 1.5% CEO. Therefore, MDCM-P coatings containing CEO could improve the storage quality of heat treated sucuks at refrigerator.


Asunto(s)
Conservación de Alimentos/métodos , Productos de la Carne/análisis , Aceites Volátiles , Animales , Bovinos , Pollos , Aceite de Clavo , Recuento de Colonia Microbiana , Manipulación de Alimentos/métodos , Almacenamiento de Alimentos , Concentración de Iones de Hidrógeno , Productos de la Carne/microbiología , Refrigeración , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Thymus (Planta)
15.
Food Microbiol ; 84: 103235, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31421765

RESUMEN

Foodborne transmission of HEV is a growing public health concern in industrialised countries, where the disease is mainly autochthonous, caused by zoonotic HEV of either genotype 3 or 4. Foodstuffs containing pig's liver were suspected on several occasions to be the cause of autochthonous cases of HEV infection, while the transmission was associated with animal contact and the ingestion of raw or uncooked meat, especially liver. In assessing the risk related to the presence of HEV in food, detection methods were previously developed but HEV detection rates seem to vary with the type of samples and methods. As foodstuff containing pig liver can be contaminated with HEV internally, an efficient virus extraction procedure is required. The aim of this study was to evaluate six methods for their efficiency in releasing HEV viral particles from figatelli, pig liver sausages and liver samples previously tested positive for the presence of HEV. The ratio weight to volume of elution buffer (1:5) and the FastPrep®-24 homogeniser showed to significantly improve the quantity of HEV genomes released per gram of figatelli and pig liver sausages. To our knowledge, this study is the first to evaluate several methods for elution of HEV particles from naturally contaminated pig liver products, and may be extended for quantifying other viral genomes from food of animal origin.


Asunto(s)
Microbiología de Alimentos/métodos , Virus de la Hepatitis E/aislamiento & purificación , Hígado/virología , Productos de la Carne/microbiología , Animales , Enfermedades Transmitidas por los Alimentos/virología , Hepatitis E/transmisión , Virus de la Hepatitis E/genética , Carne/virología , ARN Viral/genética , Porcinos
16.
Int J Food Microbiol ; 308: 108303, 2019 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-31437694

RESUMEN

Environmental conditions during ripening of dry-cured meat products favour growth of fungal population on their surface. Some of these moulds can produce mycotoxins. Paprika is one of the ingredients usually used in the formulation of raw-cured sausages, and its addition could influence the growth and production of mycotoxins of the moulds present in these products. In this work the effect of Spanish smoked paprika "Pimentón de la Vera" on growth of Aspergillus parasiticus and Penicillium nordicum and production of aflatoxins B1 (AFB1), G1 (AFG1) and ochratoxin A (OTA) respectively, was evaluated. Moulds were grown in a culture medium made from lyophilized fresh pork meat added with 4% salt and different concentrations of Spanish smoked paprika (1, 2 and 3%) at several water activity values (0.98, 0.94 and 0.87) and temperature (20-25 °C), to simulate conditions usually found during ripening of dry-cured meat products. Mould growth was evaluated by measuring the diameter of the colony every 24 h, and the production of mycotoxins by UHPLC-MS/MS every 2 days, during 10 days of incubation. Addition of paprika favours growth of the two mould species tested. However, the synthesis of mycotoxins was reduced at 0.94 and 0.98 aw when at least a 2% of paprika was added. Therefore, the addition of Spanish smoked paprika at 2-3% in the formulations may help to minimize AFs and OTA production in dry-cured meat products such as loins or "chorizo" sausages.


Asunto(s)
Aflatoxina B1/biosíntesis , Aspergillus/crecimiento & desarrollo , Capsicum/química , Productos de la Carne/microbiología , Ocratoxinas/biosíntesis , Penicillium/crecimiento & desarrollo , Animales , Aspergillus/metabolismo , Microbiología de Alimentos , Penicillium/metabolismo , Humo , Cloruro de Sodio/análisis , Porcinos , Espectrometría de Masas en Tándem , Temperatura Ambiental , Agua
18.
J Agric Food Chem ; 67(33): 9335-9343, 2019 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-31343169

RESUMEN

The ability of Debaryomyces hansenii to produce volatile sulfur compounds from sulfur amino acids and the metabolic pathway involved have been studied in seven strains from different food origins. Our results proved that l-methionine is the main precursor for sulfur compound generation. Crucial differences in the sulfur compound profile and amino acid consumption among D. hansenii strains isolated from different food sources were observed. Strains isolated from dry pork sausages displayed the most complex sulfur compound profiles. Sulfur compound production, such as that of methional, could result from chemical reactions or yeast metabolism, while according to this study, thioester methyl thioacetate appeared to be generated by yeast metabolism. No relationship between sulfur compounds production by D. hansenii strains and the expression of genes involved in sulfur amino acid metabolism was found, except for the ATF2 gene in the L1 strain for production of methyl thioacetate. Our results suggest a complex scenario during sulfur compound production by D. hansenii.


Asunto(s)
Aminoácidos Sulfúricos/metabolismo , Debaromyces/metabolismo , Productos de la Carne/análisis , Productos de la Carne/microbiología , Compuestos de Azufre/metabolismo , Animales , Debaromyces/genética , /microbiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Compuestos de Azufre/química , Porcinos , Volatilización
19.
Can J Microbiol ; 65(11): 831-841, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31310729

RESUMEN

A pork sausage was produced with low sodium content (1.64%) to which Lactobacillus sakei was added with the aim of developing a meat pork sausage for cooking and having technological, organoleptic, and hygienic advantages. The lactic acid bacteria (LAB) L. sakei, Lactococcus sp., and Pediococcus pentosaceus were submitted to extreme pH, temperature, and NaCl conditions. Lactobacillus sakei was used in pork sausage because of its resistance to different culture conditions and its antimicrobial potential. The food-borne pathogens Listeria monocytogenes Scott A, Enterococcus faecalis, and Staphylococcus aureus were used as indicator microorganisms to evaluate the antimicrobial activity of selected LAB strains. Salmonella enterica serotype Choleraesuis is a common pathogen of pigs. To the raw sausage product containing L. sakei and nonpathogenic endogenous microbiota, we added about >104 and <105 CFU/g of S. enterica serotype Choleraesuis to evaluate the inhibitory potential of L. sakei towards this pathogen. Salmonella Choleraesuis was inhibited in the presence of L. sakei over 7 days of storage of the meat product (about 3.0 log cycles reduction). Lactobacillus sakei significantly increased inhibition when compared with the nonfermented sausage. Thus, L. sakei BAS0117 played an important role as an additional hurdle in the fermented meat pork sausage during storage.


Asunto(s)
Conservación de Alimentos/métodos , Lactobacillus sakei/fisiología , Productos de la Carne/microbiología , Animales , Antibiosis , Recuento de Colonia Microbiana , Fermentación , Aditivos Alimentarios/análisis , Microbiología de Alimentos , Listeria monocytogenes/crecimiento & desarrollo , Listeria monocytogenes/fisiología , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/fisiología , Porcinos
20.
Meat Sci ; 157: 107879, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31284236

RESUMEN

The effect of coriander essential oil (CEO) at concentrations of 0.075-0.150 µL/g on pH, color, lipid oxidation (TBARS), residual nitrite concentration and microbial growth of cooked pork sausages produced with different levels of sodium nitrite (0, 50 and 100 mg/kg) was investigated. Artificial neural networks modeling and the multi-response optimization were used to determine the optimal combinations of process parameters and storage time. Reduced concentration of sodium nitrite (60 mg/kg) in combination with 0.12 µL/g of CEO resulted in satisfying redness (a* approx. 11.1) and improved oxidative (TBARS approx. 0.12 mg MDA/kg) and microbial stability (total plate count - TPC approx. 2.50 Log CFU/g) of cooked pork sausages during refrigerated storage. Therefore, the results of this paper revealed significant antioxidative and antimicrobial activity of CEO, and consequently its high potential of utilization in processing of cooked pork sausages with enhanced quality and shelf-life.


Asunto(s)
Almacenamiento de Alimentos , Productos de la Carne/microbiología , Aceites Volátiles/química , Aceites Vegetales/química , Animales , Color , Culinaria , Aditivos Alimentarios/química , Productos de la Carne/análisis , Nitrito de Sodio/química , Porcinos , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis
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