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1.
BMC Infect Dis ; 21(1): 54, 2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33435906

RESUMO

BACKGROUND: An outbreak of acute gastroenteritis occurred in a kindergarten located Shenzhen City on March 4, 2018. We were invited to investigate to the risk factors associated with this outbreak. METHODS: We conducted retrospective cohort-studies on three different groups of subjects in order to figure out the difference of incidence of acute gastroenteritis among subjects of different activities on March 2: group one consisted of people who attended the Lantern festival activities; group two consisted of children and employees who ate breakfast and bread provided by the kindergarten; and groups three consisted of children and employees who did not eat breakfast or bread provided by the kindergarten. Fecal, anal swabs, dishware swabs and hand swabs specimens were collected in the study. Bacteria known to cause acute gastroenteritis were cultured. Viruses associated with acute gastroenteritis were tested using real-time PCR. Capsid gene fragment of 557 bp of norovirus was amplified and sequenced. The phylogenetic tree was constructed with MEGA 7.0 using neighbor-joining method based on capsid gene fragment of norovirus. RESULTS: A total of 143 suspected cases were identified in this outbreak. Diarrhea happened more often in adults than in children while emesis and bellyache were more frequently found in children than in adults. Higher AGE incidence was observed in group 2, children and employees who had breakfast in the kindergarten on March 2, as well as in group 3, and among employees who eating bread involved in breakfast provided on March 2. Five anal swab specimens were positive for norovirus. All noroviruses belongs to group II.3 and have an identity more than 99%. CONCLUSION: A chef, as an asymptomatic carrier with norovirus, was the infectious resource in this outbreak. He contaminated breakfast food provided on March 2. Although morning check is implemented in kindergartens of China, employees are often excluded in morning check. Our finding highlights the importance of morning check covering employees and periodical training for cooks.


Assuntos
Desjejum , Infecções por Caliciviridae/epidemiologia , Portador Sadio/virologia , Surtos de Doenças , Manipulação de Alimentos , Gastroenterite/epidemiologia , Norovirus/genética , Escolas Maternais , Adulto , Infecções por Caliciviridae/diagnóstico , Infecções por Caliciviridae/prevenção & controle , Infecções por Caliciviridae/virologia , Criança , Pré-Escolar , China/epidemiologia , Diarreia/epidemiologia , Diarreia/virologia , Fezes/virologia , Feminino , Microbiologia de Alimentos/métodos , Gastroenterite/diagnóstico , Gastroenterite/prevenção & controle , Gastroenterite/virologia , Humanos , Incidência , Masculino , Filogenia , Quarentena/métodos , Reação em Cadeia da Polimerase em Tempo Real , Estudos Retrospectivos , Fatores de Risco , Vômito/epidemiologia , Vômito/virologia
2.
Food Chem ; 340: 127935, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32891895

RESUMO

This study aimed at evaluating mitigation of nivalenol (NIV) in alcoholic fermentation with magnetic field application (MF). Mitigation was related to both the glutathione (GSH) redox molecule and the enzyme peroxidase (PO), which were synthesized by Saccharomyces cerevisiae US-05. Conditions under evaluation were NIV (0.2 µg mL-1), MF application (35 mT) and simultaneous use of mycotoxin and MF. The GSH content and the PO activity were increased when the culture contained NIV and the alcohol profile was altered after 48 h of fermentation. At the end of the alcoholic fermentation, NIV was mitigated by 56.5%. Therefore, this process is a promising method to reduce contamination by NIV, although the mycotoxin affects the chemical characteristics of the final product.


Assuntos
Bebidas Alcoólicas , Microbiologia de Alimentos/métodos , Tricotecenos/metabolismo , Etanol/análise , Fermentação , Glutationa/metabolismo , Campos Magnéticos , Micotoxinas/química , Peroxidases/metabolismo , Saccharomyces cerevisiae/metabolismo
3.
Food Chem ; 340: 128104, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33010644

RESUMO

Bacteria release membrane vesicles into the extracellular environment but which activity is unclear. We investigated the applications of extracellular vesicles (EVs) isolated from probiotic Lactobacillus plantarum to protect tuna fish against spoilage and quality loss in this study. A significant difference was found in EVs size obtained from L. plantarum after 8, 24, and 48 hr incubation. The L. plantarum-derived EVs were collected and used to confirm the anti-bacterial activity versus Shewanella putrefaciens. Finally, the tuna fish was stored at 4 °C for 5 days after coating with EVs or sodium erythorbate, and the quality indexes were assayed. Results indicated that EVs markedly inhibited oxidation reaction, total volatile base nitrogen (TVBN), peroxide value (PV), malondialdehyde (MDA), and bacteria levels. These results finding out that EVs from L. plantarum may have potential for application in food storage technology. Overall, we indicated this new material may be developed as an anti-bacterial agent for prolonging the shelf life of tuna fish.


Assuntos
Antibacterianos/farmacologia , Vesículas Extracelulares , Produtos Pesqueiros/microbiologia , Microbiologia de Alimentos/métodos , Lactobacillus plantarum/citologia , Animais , Antibacterianos/química , Armazenamento de Alimentos , Malondialdeído/metabolismo , Oxirredução , Probióticos , Shewanella putrefaciens/efeitos dos fármacos , Shewanella putrefaciens/crescimento & desenvolvimento , Atum/microbiologia
4.
Int J Food Microbiol ; 337: 108932, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33152570

RESUMO

Culturing methods are conventionally applied to investigate the contamination of food with several microorganisms after heat processing. However, with these methods, it is not possible to evaluate whether heat-treated meat products, such as cooked sausages, contained parts of spoiled meat. Therefore, two specific multiplex qPCRs were developed in this study in order to determine the microbiological quality of the raw materials used for these products. The PCR targets focused on four bacterial groups often found on meat (family Enterobacteriaceae, genus Pseudomonas, genus Staphylococcus and species Brochothrix thermosphacta). Specificity as well as sensitivity of the developed multiplex qPCRs, validated by using 68 microbial species, were 100%. The applicability of both multiplex qPCRs compared to culturing methods was performed using 96 meat samples (fresh and naturally spoiled) and 12 inhouse-made "Lyoner" sausages containing variable ratios of spoiled meat (0%, 5%, 12% and 25%; n = 3 for each group). Both methods showed similar results by evaluating the ∆log10 cfu/g, the relative accuracy and the t-test analysis (p > 0.05). Comparing qPCR results of the different sausage groups, a significant difference between sausages containing fresh meat and sausages containing spoiled meat (12% and 25%) was found only for Pseudomonas and B. thermosphacta in both raw and cooked sausages. The statistical difference between 5% vs. 12% and 25% spoiled meat in cooked sausages, was also found only for these two bacterial groups. The developed multiplex qPCRs were further applied to 30 commercially available "Bologna-type" sausages. The results showed a total of 14 sausages considered to be suspicious for Food Fraud. While the role of Staphylococcus spp. in meat spoilage remains unclear, Pseudomonas, Enterobacteriaceae and B. thermosphacta could together be used as an indicator for "spoiled meat" used in sausages. The developed qPCR systems in this study allow the detection of four relevant bacterial groups in the heated Bologna-type sausages and provide information about the hygienic quality of raw materials used. This method could thus be helpful for screening food suspected of Food Fraud.


Assuntos
Bactérias/genética , Microbiologia de Alimentos/métodos , Produtos da Carne/microbiologia , Carne/microbiologia , Reação em Cadeia da Polimerase , Animais , Brochothrix/genética , Enterobacteriaceae/genética , Temperatura Alta , Pseudomonas/genética , Staphylococcus/genética
5.
Int J Food Microbiol ; 337: 108936, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33161345

RESUMO

Development of novel and effective decontamination technologies to ensure the microbiological safety of fresh produce has gained considerable attention, mainly driven by numerous outbreaks. This work presented the first approach regarding to the application of the previously reported hurdle technologies on the sanitization of artificially contaminated cherry tomatoes. Thyme (Thymus daenensis) essential oil nanoemulsion (TEON, 8.28 nm in diameter with a narrow size distribution) was formulated via ultrasonic nanoemulsification, showing remarkably improved antimicrobial activity against Escherichia coli (E. coli) O157:H7, compared to the coarse emulsion. The antimicrobial effect of ultrasound (US), thyme essential oil nanoemulsion (TEON) and the combination of both treatments was assessed against E. coli O157:H7. The remarkable synergistic effects of the combined treatments were achieved, which decontaminated the E. coli populations by 4.49-6.72 log CFU/g on the surface of cherry tomatoes, and led to a reduction of 4.48-6.94 log CFU/sample of the total inactivation. TEON combined with US were effective in reducing the presence of bacteria in wastewater, which averted the potential detrimental effect of cross-contamination resulted from washing wastewater in fresh produce industry. Moreover, the treatments did not noticeably alter the surface color and firmness of cherry tomatoes. Therefore, ultrasound combined with TEON is a promising and feasible alternative for the reduction of microbiological contaminants, as well as retaining the quality characteristics of cherry tomatoes.


Assuntos
Descontaminação/métodos , Escherichia coli O157/efeitos dos fármacos , Escherichia coli O157/efeitos da radiação , Microbiologia de Alimentos/métodos , Óleos Voláteis/farmacologia , Ondas Ultrassônicas , Contagem de Colônia Microbiana , Lycopersicon esculentum/microbiologia
6.
Food Chem ; 338: 127837, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32818863

RESUMO

Early screening of L. monocytogenes in ready-to-eat food can prevent and control its harmful effects. In this study, we propose a highly sensitive magnetic DNA sensor based on nucleic acid hybridization reaction and magnetic signal readout. We design the L. monocytogenes specific probe1 and probe2 and label them on the 30 and 250 nm magnetic nanoparticles, respectively. The hybridization reaction between the magnetic probes and DNA of L. monocytogenes could form a sandwich nanocomplex. After magnetic separation, the unbound MNP30-probe2 can act as the transverse relaxation time (T2) signal readout probe. This assay allows the one-step detection of L. monocytogenes as low as 50 CFU/mL within 2 h without DNA amplification, and the average recovery in the spiked ham sausage samples can reach 92.6%. This system integrates the high sensitivity of magnetic sensing and high efficiency of hybridization reaction, providing a promising detection platform for pathogens.


Assuntos
Microbiologia de Alimentos/métodos , Listeria monocytogenes , Produtos da Carne/microbiologia , Hibridização de Ácido Nucleico/métodos , Sondas de DNA , DNA Bacteriano , Listeria monocytogenes/genética , Fenômenos Magnéticos , Espectroscopia de Ressonância Magnética , Nanopartículas/química , Técnicas de Amplificação de Ácido Nucleico
7.
Food Chem ; 339: 127775, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32916400

RESUMO

Carbon quantum dots (CQDs) prepared by a green one-step approach was used for sensitive and selective assay of Escherichia coli O157: H7 (E. coli). CQDs was synthesized from orange peel as a carbon source via a microwave-assisted method. The CQDs displayed strong green fluorescence under excitation wavelength of 420 nm. A fluorescent probe (CQDs-MNPs) for E. coli was fabricated based on CQDs labeled with aptamer (aptamer-CQDs) and magnetic nanoparticles labeled with complementary DNA (cDNA-MNPs). Fluorescent intensity of the CQDs-MNPs was decreased with addition of E. coli. The linearity between fluorescent intensity and E. coli concentration was used for developing a fluorescent method with detecting range of 500-106 CFU/mL and detection limit of 487 CFU/mL. Milk samples contaminated by E. coli were analyzed by this method, and the results agreed with that achieved by plate-counting methods. This fluorescent probe exhibits great potential in guaranteeing food quality and safety.


Assuntos
Carbono/química , Citrus sinensis/química , Escherichia coli , Microbiologia de Alimentos/métodos , Leite/microbiologia , Pontos Quânticos/química , Animais , Fluorescência , Corantes Fluorescentes/química , Microbiologia de Alimentos/instrumentação , Química Verde , Limite de Detecção , Nanopartículas/química
8.
Int J Food Microbiol ; 337: 108913, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33126077

RESUMO

Recently, unexpected contaminations of unauthorized genetically modified microorganisms (GMM) carrying antimicrobial resistance (AMR) genes were reported in microbial fermentation products commercialized on the food and feed chain. To guarantee the traceability and safety of the food and feed chain, whole-genome sequencing (WGS) has played a key role to prove GMM contaminations via the characterization of unnatural associations of sequences. However, WGS requires a prior microbial isolation of the GMM strain, which can be difficult to successfully achieve. Therefore, in order to avoid such bottleneck, a culture-independent approach was proposed in this study. First, the screening for the aadD gene, an AMR gene conferring a resistance to kanamycin, and for the pUB110 shuttle vector, carrying the aadD gene and commonly used to produce GMM, is performed. In case of a positive signal, DNA walking methods anchored on the two borders of the detected pUB110 shuttle vector are applied to characterize unknown flanking regions. Following to the sequencing of the generated amplicons, unnatural associations of sequences can be identified, allowing to demonstrate the presence of unauthorized GMM. The developed culture-independent strategy was successfully applied on commercialized microbial fermentation products, allowing to prove the presence of GMM contaminations in the food and feed chain.


Assuntos
Bactérias/genética , Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos/métodos , Microbiologia Industrial/métodos , Análise de Sequência de DNA/métodos , DNA/química , Fermentação , Alimentos Geneticamente Modificados/microbiologia , Sequenciamento Completo do Genoma
9.
Int J Food Microbiol ; 337: 108914, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33166913

RESUMO

A collection of 23 Listeria monocytogenes strains of clinical and food origin was tested for their ability to recover and grow out in half Fraser enrichment broth following the ISO 11290-1:2017 protocol. Recovery of sub-lethally heat-injured cells in half Fraser broth was compared to reference cells with no stress pre-treatment. The enrichments were followed over time by plate counts and the growth parameters were estimated with the 3-phase model which described the data best. The reference cells without stress pre-treatment showed a short lag duration, which ranged from 1.4 to 2.7 h. However, significant variation in the ability to recover after 60 °C heat stress was observed among the tested strains and resulted in a lag duration from 4.7 to 15.8 h. A subset of strains was also exposed to low-temperature acid stress, and the lag duration showed to be also stress dependent. Scenario analyses and Monte Carlo simulations were carried out using the growth parameters obtained in the enrichments. This demonstrated that when starting with one cell, the detection threshold for efficient transfer of at least one cell to the secondary enrichment step, i.e. 2 log10 CFU/ml, was not reached by 11 of 23 strains tested (48%) after exposure to 60 °C heat stress. Increasing the incubation time from 24 to 26 h and the transfer volume from 0.1 to 1.0 ml can increase the average probability to transfer at least one cell to the secondary enrichment step from 79.9% to 99.0%. When optimizing enrichment procedures, it is crucial to take strain variability into account as this can have a significant impact on the detection efficacy.


Assuntos
Meios de Cultura/química , Microbiologia de Alimentos/métodos , Listeria monocytogenes/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Listeria monocytogenes/metabolismo
10.
Int J Food Microbiol ; 337: 108955, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33186831

RESUMO

Probabilistic topic modelling is frequently used in machine learning and statistical analysis for extracting latent information from complex datasets. Despite being closely associated with natural language processing and text mining, these methods possess several properties that make them particularly attractive in metabolomics applications where the applicability of traditional multivariate statistics tends to be limited. The aim of the study was thus to introduce probabilistic topic modelling - more specifically, Latent Dirichlet Allocation (LDA) - in a novel experimental context: volatilome-based (sea) food spoilage characterization. This was realized as a case study, focusing on modelling the spoilage of Atlantic salmon (Salmo salar) at 4 °C under different gaseous atmospheres (% CO2/O2/N2): 0/0/100 (A), air (B), 60/0/40 (C) or 60/40/0 (D). First, an exploratory analysis was performed to optimize the model tunings and to consequently model salmon spoilage under 100% N2 (A). Based on the obtained results, a systematic spoilage characterization protocol was established and used for identifying potential volatile spoilage indicators under all tested storage conditions. In conclusion, LDA could be used for extracting sets of underlying VOC profiles and identifying those signifying salmon spoilage, giving rise to an extensive discussion regarding the key points associated with model tuning and/or spoilage analysis. The identified compounds were well in accordance with a previously established approach based on partial least squares regression analysis (PLS). Overall, the outcomes of the study not only reflect the promising potential of LDA in spoilage characterization, but also provide several new insights into the development of data-driven methods for food quality analysis.


Assuntos
Microbiologia de Alimentos/métodos , Modelos Estatísticos , Salmo salar/microbiologia , Alimentos Marinhos/microbiologia , Animais , Microbiologia de Alimentos/normas , Qualidade dos Alimentos , Armazenamento de Alimentos , Gases/análise , Metabolômica , Compostos Orgânicos Voláteis/análise
11.
Int J Food Microbiol ; 337: 108931, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33188986

RESUMO

Among the enteric viruses implicated in foodborne outbreaks, the human norovirus and hepatitis viruses A and E (HAV and HEV) represent a serious public health concern. International standard ISO 15216 proposes methods for detecting HAV and norovirus (genogroups I and II) RNA from soft fruit, leaf, stem and bulb vegetables, bottled water or food surfaces. These methods had not previously been validated for detecting the targeted viruses in other foodstuffs such as multicomponent foods, nor for detecting other viruses in foodstuffs. The aim of this study was to characterise a method derived from the vegetable method described in ISO 15216 to detect HAV, HEV and norovirus in artificially-contaminated multicomponent foodstuffs according to the recent international standard ISO 16140-4. Results showed that the mean recovery rates for all settings did not differ according to the operator. The mean extraction yields ranged from 0.35% to 40.44% for HAV, 5.19% to 100% for HEV, 0.10% to 40.61% for norovirus GI and 0.88% to 69.16% for norovirus GII. The LOD95 was 102 genome copies/g for HAV, HEV and norovirus GII and 103 genome copies/g for norovirus GI. The LOQ was 2.90 × 104, 1.40 × 103, 1.60 × 104 and 1.30 × 104 genome copies/g for HAV, HEV, norovirus GI and norovirus GII respectively. The MNV-1 process control was detected in 120 out of 128 RNA extracts analysed and was recovered with an efficiency of between 3.83% and 50.22%. The mean inhibition rates of quantitative real-time RT-PCR reaction ranged from 3.25% to 28.70% and varied significantly with the type of food matrix. The described method could be used to detect viruses in composite food products for routine diagnosis needs.


Assuntos
Microbiologia de Alimentos/métodos , Vírus da Hepatite A/genética , Vírus da Hepatite E/genética , Norovirus/genética , Surtos de Doenças/prevenção & controle , Água Potável/virologia , Frutas/virologia , Vírus da Hepatite A/fisiologia , Limite de Detecção , RNA Viral/análise , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real , Verduras/virologia
12.
Int J Food Microbiol ; 337: 108949, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33220648

RESUMO

The 2014 listeriosis outbreak caused by caramel-coated apples was linked to apples cross-contaminated within an apple packing facility. This outbreak has increased the focus on effective cleaning and sanitation methods that must be validated and monitored during apple packing. Thus, rapid and reliable testing methods are necessary for assessing cleanliness in the apple packing industry. The objectives of this study were to assess the prevalence of common indicator organisms [Aerobic plate count (APC), Enterobacteriaceae, coliforms, Escherichia coli, and Listeria spp.] on food contact surfaces (zone 1) in apple packinghouses and to evaluate the utility and accuracy of currently used rapid tests (ATP and glucose/lactose residue swabs). Food contact surfaces were sampled over a 100 cm2 area in five commercial apple packinghouses to evaluate populations of indicator organisms APC, Enterobacteriaceae, coliforms, E. coli (n = 741), and rapid test readings (n = 659). Petrifilm plates were used for the quantification of APC, Enterobacteriaceae, and coliform/E. coli. Rapid tests [ATP swabs (UltraSnap) and glucose/lactose residue swabs (SpotCheck Plus)] were processed on-site. A larger area (0.93 m2) was sampled for the detection of Listeria spp. (n = 747), following a modified protocol of the FDA's Bacteriological Analytical Manual method, and confirmed with PCR and gel electrophoresis via the iap gene. No significant association was found between either rapid test and populations of APC, Enterobacteriaceae, coliforms, E. coli, and Listeria spp. detection. However, recovery of APC (log CFU/100 cm2) was higher with a failed glucose/lactose residue swab surface hygiene result (3.1) than a passed result (2.9) (p = 0.03). Populations of APC, Enterobacteriaceae, and coliforms were significantly different at each unit operation during the packing process (p ≤ 0.05). This study concluded that ATP and glucose/lactose residue rapid tests were poorly suited for determining microbial load since they were not related to populations of any common indicator organisms or the detection of Listeria spp. These findings emphasize the need to utilize a rapid test, which can be a good indicator of residual matter on a surface, along with traditional microbiological methods to assess cleaning and sanitation practices in apple packinghouses.


Assuntos
Bactérias/isolamento & purificação , Técnicas Bacteriológicas/métodos , Manipulação de Alimentos/estatística & dados numéricos , Microbiologia de Alimentos , Malus/microbiologia , Bactérias/classificação , Contagem de Colônia Microbiana , Biomarcadores Ambientais , Microbiologia de Alimentos/métodos , Microbiologia de Alimentos/estatística & dados numéricos , Higiene , Prevalência
13.
Int J Food Microbiol ; 339: 109014, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33333444

RESUMO

The objective of this study was to develop a method with improved sensitivity for Campylobacter jejuni detection in foods. Nitrogen-doped carbon nanodots (N-CNDs) were synthesized and added to an enrichment medium (Bolton broth) at a concentration of 10 mg/mL. A light-emitting diode (LED) at a wavelength of 425 nm was used to irradiate the N-CNDs-supplemented enrichment medium to induce an exothermic reaction for 1 h. Additionally, a monoclonal antibody specific to C. jejuni NCTC11168 was developed using hybridoma cells to aid detection. The C. jejuni detection capabilities of N-CNDs-supplemented enrichment medium and the conventional Bolton broth enrichment, were compared using duck samples. C. jejuni in the enrichment was detected with the monoclonal antibody based-indirect enzyme-linked immunosorbent assay (ID-ELISA). The N-CNDs-supplemented enrichment medium showed a better C. jejuni detection capability than the conventional Bolton broth enrichment. Additionally, data from ID-ELISA showed excellent detection efficiency and a shortened detection time in the N-CNDs-supplemented enrichment medium after LED irradiation at 425 nm. These results indicate that 1-h LED irradiation at 425 nm to Bolton broth supplemented with the N-CNDs increased the detection efficiency and shortened the detection time with the monoclonal antibody for C. jejuni in food.


Assuntos
Campylobacter jejuni/isolamento & purificação , Ensaio de Imunoadsorção Enzimática , Microbiologia de Alimentos/métodos , Carne/microbiologia , Nanopartículas/química , Animais , Anticorpos Monoclonais/metabolismo , Bactérias/efeitos dos fármacos , Carbono/química , Carbono/farmacologia , Meios de Cultura , Patos/microbiologia , Nitrogênio/química , Nitrogênio/farmacologia
14.
Int J Food Microbiol ; 339: 109007, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33341684

RESUMO

Cast films obtained from polyvinyl alcohol (PVOH) blended with casein hydrolysates (HCas) in a weight ratio of 1:1 were employed to carry nisin-producing L. lactis and phytic acid in order to broaden the antimicrobial spectrum of L. lactis to Gram-positive and Gram-negative spoilage and pathogen bacteria. For this purpose, the effect of the antimicrobial activity of various film formulations and combinations of films on the growth of E. coli at 37 °C for 24 h was studied. The film system that showed antimicrobial activity against Gram-negative bacteria consisted of phytic acid and L. lactis incorporated in separate films. When the active agents were in the same film the viability of L. lactis decreased considerably and it did not exert antimicrobial activity against the bacterium. Therefore, the combination of L. lactis and phytic acid in separate films was chosen as the reliable system, and the effect of its activity on the growth of Gram-negative bacteria (E. coli, Salmonella enterica, and Pseudomonas fluorescens) and Gram-positive bacteria (Listeria monocytogenes) in liquid culture medium was tested at refrigeration temperature (4 °C), and with simulated breaks in the cold chain (14 °C and 24 °C). The survival of L. lactis in coexistence with these bacteria was also studied. The film system exerted an antimicrobial effect against the Gram-negative bacteria tested, and the activity depended on the bacteria and the temperature assayed. With regard to the antimicrobial activity against L. monocytogenes, phytic acid improved the antimicrobial capacity of L.lactis. The survival of L. lactis was maintained at 7-8 log (CFU/mL) culture in liquid medium throughout the storage period. The films developed were intended to be used as coatings in the design of a double-sided active bag for a non-fermented dairy product. The bags were filled with homemade preservative-free pastry cream, and the microbiological shelf life and evolution of pH of the packaged ready-to-eat food stored at 4 °C was studied for 20 days. The results showed a reduction in the growth of spoilage bacteria and therefore an increase in the shelf life of the packaged product. The films developed could be applied in the design of packages for perishable dairy foods in order to increase their microbiological shelf life.


Assuntos
Microbiologia de Alimentos/métodos , Embalagem de Alimentos/métodos , Bactérias Gram-Negativas/efeitos dos fármacos , Lactococcus lactis/metabolismo , Nisina/farmacologia , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Contagem de Colônia Microbiana , Bactérias Gram-Positivas/efeitos dos fármacos , Lactococcus lactis/crescimento & desenvolvimento , Nisina/metabolismo , Álcool de Polivinil/química , Refrigeração
15.
Int J Food Microbiol ; 339: 109016, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33360159

RESUMO

Dry-fermented sausages are prone to be colonised by Penicillium nordicum, which is one of the main ochratoxin A (OTA)-producing species. Its ability to produce this mycotoxin on dry-fermented sausages has been reported. However, the influence of the conditions of a traditional processing of a Spanish dry-fermented sausage and the intrinsic physicochemical parameters of this product such as water activity (aw) and pH on OTA production has not been studied yet. Thus, the aim of this study was to evaluate the influence of traditional processing (interaction of relative humidity (RH) x temperature x ripening days) on the evolution of pH and aw during maturation of dry-fermented sausage "salchichón" and its relationship with OTA synthesis by P. nordicum. The expression of otapks and otanps genes, both involved in the biosynthesis of the mycotoxin, was also assessed. For this, 27 raw sausages were inoculated with P. nordicum and ripened for 26 days in a drying chamber (3 days at 5 °C and 84% RH, 17 days at 12 °C and 84% RH, and 6 days at 12 °C and 80% RH). From results, although it seems that the pH slightly influenced on OTA biosynthesis, the aw had a great impact on this mycotoxin production. In fact, the two highest OTA concentrations found coincided with a dramatic rise of the aw value (0.92 aw) by day 18 of incubation when the RH of the drying chamber was still 84% and at the end of the incubation time when the aw decreased noticeably (0.87 aw). The expression of the otapks and otanps genes correlated with the OTA produced by P. nordicum. Results from this work confirm that the traditional processing of Spanish dry-fermented sausages favours itself OTA synthesis by P. nordicum. Our findings may help in informed decision-making in relation to RH/temperature of drying chambers and shortening of the ripening process. This may be then effectively incorporated into the hygienic production system in the framework of HACCP together with other measures including the use of Penicillium nalgiovense as protective culture or the monitoring of otapks gene expression, and aw during the processing of dry-fermented sausages. All these strategies together may put ochratoxigenic Penicillia at a disadvantage and minimise OTA contamination risks in dry-fermented sausages.


Assuntos
Manipulação de Alimentos/métodos , Microbiologia de Alimentos/métodos , Produtos da Carne/microbiologia , Ocratoxinas/metabolismo , Penicillium/metabolismo , Animais , Dessecação , Fermentação , Perfilação da Expressão Gênica , Genes Bacterianos/genética , Concentração de Íons de Hidrogênio , Produtos da Carne/análise , Ocratoxinas/análise , Penicillium/genética , Suínos , Temperatura , Tempo , Água/metabolismo
16.
Food Chem ; 334: 127560, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32711271

RESUMO

Post-fermented Pu-erh tea (PFPT) is a microbially-fermented tea with distinct sensory qualities and multiple health benefits. Aspergillus are the dominant fungi in the fermentation and the main contributors to the characteristics of PFPT, so their underlying functions warrant detailed study. Here, tea leaves were fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus, and resulting samples (designated as Asn, Ast and Asf, respectively) were analyzed by proteomic and metabolomic methods. Changes to the composition of flavonoids, glycerophospholipids, organo-oxygen compounds and fatty acids resulting from Aspergillus fermentation were observed. Carbohydrate-active enzymes, e.g., endoglucanases and cellulases, for degradation of cellulose, starch, lignin, pectin, xylan and xyloglucan were identified. Glycoside hydrolase, glycosyltransferases, tannase, laccases, vanillyl-alcohol oxidases and benzoquinone reductase were identified and hypothesized to catalyze hydrolysis, oxidation, polymerization and degradation of phenolic compounds. Together, functions of Aspergillius were demonstrated as production of enzymes to change concentrations and compositions of metabolites in tea leaves.


Assuntos
Aspergillus/fisiologia , Camellia sinensis/microbiologia , Enzimas/metabolismo , Folhas de Planta/microbiologia , Chá , Aspergillus/enzimologia , Aspergillus fumigatus/enzimologia , Aspergillus fumigatus/fisiologia , Aspergillus niger/enzimologia , Aspergillus niger/fisiologia , Metabolismo dos Carboidratos , Fermentação , Flavonoides/análise , Flavonoides/metabolismo , Microbiologia de Alimentos/métodos , Proteínas Fúngicas/metabolismo , Glicerofosfolipídeos/metabolismo , Metabolômica/métodos , Fenóis/análise , Fenóis/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Proteínas de Plantas/análise , Proteínas de Plantas/metabolismo , Proteômica/métodos , Chá/química , Chá/metabolismo , Chá/microbiologia
17.
Food Chem ; 334: 127608, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32711280

RESUMO

Food analysis to ensure food safety and quality are relevant to all countries. This study aimed to develop a detection technique by combining recombinase polymerase amplification with CRISPR-Cas12a for food safety (termed RPA-Cas12a-FS). Our data showed that this novel method could be detected via fluorescence intensity for the molecular identification of foodborne pathogenic bacteria, genetically modified crops, and meat adulteration. After optimization, the sensitivity and stability of RPA-Cas12a-FS was further enhanced. The RPA-Cas12a-FS system could specifically detect target gene levels as low as 10 copies in 45 min at 37 °C. The RPA-Cas12a-FS system was sensitive both using standard samples in the lab and using samples from the field, which indicated that this detection method was practical. In conclusion, a simple, rapid, and highly sensitive detection method based on CRISPR-Cas12a was developed for molecular identification in the food safety field without requiring technical expertise or ancillary equipment.


Assuntos
Sistemas CRISPR-Cas , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Microbiologia de Alimentos/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Proteínas de Bactérias/genética , Proteínas Associadas a CRISPR/genética , Produtos Agrícolas/genética , Endodesoxirribonucleases/genética , Fluorescência , Inocuidade dos Alimentos , Carne , Plantas Geneticamente Modificadas/genética , RNA Guia , Recombinases/genética , Sensibilidade e Especificidade
18.
Int J Food Microbiol ; 338: 108995, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33316593

RESUMO

Infectious human diseases acquired from bivalve shellfish consumption constitute a public health threat. These health threats are largely related to the filter-feeding phenomenon, by which bivalve organisms retain and concentrate pathogenic bacteria from their surrounding waters. Even after depuration, bivalve shellfish are still involved in outbreaks caused by pathogenic bacteria, which increases the demand for new and efficient strategies to control transmission of shellfish infection. Bacteriophage (or phage) therapy represents a promising, tailor-made approach to control human pathogens in bivalves, but its success depends on a deep understanding of several factors that include the bacterial communities present in the harvesting waters, the appropriate selection of phage particles, the multiplicity of infection that produces the best bacterial inactivation, chemical and physical factors, the emergence of phage-resistant bacterial mutants and the life cycle of bivalves. This review discusses the need to advance phage therapy research for bivalve decontamination, highlighting their efficiency as an antimicrobial strategy and identifying critical aspects to successfully apply this therapy to control human pathogens associated with bivalve consumption.


Assuntos
Bactérias/virologia , Bacteriófagos/fisiologia , Microbiologia de Alimentos/métodos , Doenças Transmitidas por Alimentos/prevenção & controle , Frutos do Mar/microbiologia , Animais , Doenças Transmitidas por Alimentos/microbiologia , Doenças Transmitidas por Alimentos/virologia , Humanos
19.
Int J Food Microbiol ; 338: 109012, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33321397

RESUMO

Fusarium culmorum and F. proliferatum can grow and produce, respectively, zearalenone (ZEA) and fumonisins (FUM) in different points of the food chain. Application of antifungal chemicals to control these fungi and mycotoxins increases the risk of toxic residues in foods and feeds, and induces fungal resistances. In this study, a new and multidisciplinary approach based on the use of bioactive ethylene-vinyl alcohol copolymer (EVOH) films containing pure components of essential oils (EOCs) and machine learning (ML) methods is evaluated. Bioactive EVOH-EOC films were made incorporating cinnamaldehyde (CINHO), citral (CIT), isoeugenol (IEG) or linalool (LIN). Several ML methods (neural networks, random forests and extreme gradient boosted trees) and multiple linear regression (MLR) were applied and compared for modeling fungal growth and toxin production under different water activity (aw) (0.96 and 0.99) and temperature (20 and 28 °C) regimes. The effective doses to reduce fungal growth rate (GR) by 50, 90 and 100% (ED50, ED90, and ED100) of EOCs in EVOH films were in the ranges 200 to >3330, 450 to >3330, and 660 to >3330 µg/fungal culture (25 g of partly milled maize kernels in Petri dish), respectively, depending on the EOC, aw and temperature. The type of EVOH-EOC film and EOC doses significantly affected GR in both species and ZEA and FUM production. Temperature also affected GR and aw only affected GR and FUM production of F. proliferatum. EVOH-CIT was the most effective film against both species and ZEA and FUM production. Usually, when the EOC levels increased, GR and mycotoxin levels in the medium decreased although some treatments in combination with certain aw and temperature values induced ZEA production. Random forest models predicted the GR of F. culmorum and F. proliferatum and ZEA and FUM production better than neural networks or extreme gradient boosted trees. The MLR mode provided the worst performance. This is the first approach on the ML potential in the study of the impact that bioactive EVOH films containing EOCs and environmental conditions have on F. culmorum and F. proliferatum growth and on ZEA and FUM production. The results suggest that these innovative packaging systems in combination with ML methods can be promising tools in the prediction and control of the risks associated with these toxigenic fungi and mycotoxins in food.


Assuntos
Microbiologia de Alimentos/métodos , Fusarium/efeitos dos fármacos , Fusarium/metabolismo , Aprendizado de Máquina , Micotoxinas/análise , Óleos Voláteis/farmacologia , Polivinil/química , Antifúngicos/farmacologia , Fusarium/crescimento & desenvolvimento , Micotoxinas/biossíntese
20.
Int J Food Microbiol ; 338: 108993, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33310209

RESUMO

Fungal spoilage in fruit juices is a currently relevant issue considering that recent reports have found unacceptable fungal levels even after traditional pasteurization processes. Ohmic heating demonstrated to be a good alternative process to conventional pasteurization, as it can promote higher heating rates and additional cell damage in some scenarios (nonthermal effects). However, the application of ohmic processing for fungi inactivation has not been properly investigated. The objective of this study was to analyze the inactivation of Aspergillus fumigatus, a highly distributed fungi species, in apple juice by ohmic and conventional heating at 75, 80, 85, 90 and 94 °C. Predictive primary and secondary models were fitted and the Weibull-Mafart models were the most accurate to describe the experimental behavior considering the statistical indices applied. Statistical differences between both thermal processes were found in the three lower analyzed temperatures (75, 80 and 85 °C), which is possibly related to nonthermal effects. When ohmic heating was applied, processing time was up to 23% shorter. The resulted model was successfully validated in two distinct temperatures (83 and 92 °C) and could be applied to obtain adequate processing times for apple juice pasteurization. This study contributes to deepen the knowledge concerning the use of ohmic heating for fungi inactivation.


Assuntos
Aspergillus fumigatus/fisiologia , Eletricidade , Microbiologia de Alimentos/métodos , Sucos de Frutas e Vegetais/microbiologia , Malus/microbiologia , Pasteurização , Temperatura
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