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1.
Food Microbiol ; 109: 104145, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309427

RESUMO

A cross-sectional study was conducted to investigate the prevalence and risk factors for contamination of Ethiopian dairy products with Campylobacter. A total of 912 dairy food samples were collected from establishments of 682 study participants that were interviewed. Samples were tested for Campylobacter by following the ISO 10272-1:2017 standard and PCR confirmation. Campylobacter was detected in 11% of tested food samples and all detected Campylobacter were C. jejuni. The highest prevalence of C. jejuni was found in raw milk (16%), followed by pasteurized milk (9%) and cottage cheese (2%) (P < 0.001). Using warm water and soap for cleaning cow udders and teats on farms reduced the likelihood of detecting Campylobacter in milk (AOR = 0.3, P = 0.023). Filtering milk with a cloth, using a plastic filter (AOR = 0.065, P = 0.005), and storing milk in an aluminum container (AOR = 0.23, P = 0.027) reduced the likelihood of detecting Campylobacter in milk at the collection facilities. In contrast, Campylobacter detection was significantly more likely in milk collected at collection centers with concrete floors (AOR = 5.2, P = 0.004). The odds of detecting Campylobacter in milk were 17 times greater (AOR = 17, P = 0.007) in milk processing facilities that did not calibrate a pasteurizer on an annual basis. Finally, having a separate refrigerator for milk storage reduced the odds of detecting Campylobacter in retail (AOR = 0.29, P = 0.021).


Assuntos
Campylobacter jejuni , Campylobacter , Bovinos , Animais , Feminino , Leite , Campylobacter/genética , Etiópia/epidemiologia , Prevalência , Estações do Ano , Estudos Transversais , Fatores de Risco , Microbiologia de Alimentos
2.
Food Microbiol ; 109: 104121, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309433

RESUMO

In oenology, there is a growing demand by consumers for wines produced with less inputs (such as sulphite, frequently used for microbial control). Emerging control methods for managing microorganisms in wine are widely studied. In this study, the efficiency of pulsed light (PL) treatment was investigated. A drop-platted system was used to evaluate the impact of three PL operational parameters: the fluence per flash, the total fluence and the flash frequency. Fluence per flash appeared to be a key parameter prior to total fluence, thus demonstrating the importance of the effect of peak voltage during PL treatments. The efficiency of PL treatment was assessed on 198 strains distributed amongst fourteen yeast species related to wine environment, and an important variability in PL response was observed. Brettanomyces bruxellensis strains were strongly sensitive to PL, with intraspecific variation. PL was then applied to red wines inoculated with 9 strains of B. bruxellensis, Saccharomyces cerevisiae and Lachancea thermotolerans. Results confirmed interspecific response variability and a higher sensitivity of B. bruxellensis species to PL. Wine treatments with a total fluence of 22.8 J cm-2 resulted in more than 6 log reduction for different B. bruxellensis strains. These results highlight the potential of PL for wine microbial stabilization.


Assuntos
Brettanomyces , Vinho , Vinho/análise , Microbiologia de Alimentos , Saccharomyces cerevisiae , Sulfitos/farmacologia
3.
Food Microbiol ; 109: 104122, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309434

RESUMO

Pseudomonas fragi and Escherichia coli are considered as common colonizers of fresh and spoilage meat, where they tend to live in the proximity. In this study, we primarily tested interplay patterns between different isolates of these two species in two-by-two combinations grown on stainless steel surfaces as dual-species biofilms. Results showed that these two species presented competition as major observed interplay patterns as biofilms progressed independent of bacterial strains and growth temperatures (15 °C and 25 °C). One dual-species combination was proposed as a representative to further explore dynamic patterns of interaction strength between these two species, with species colonization order taken into consideration as a biological effector. We firstly reported that prior colonization of one species significantly decreased the initiatively colonized cell counts of counterpart species by one to three orders of magnitude when competing for limited adhesion surface, under which E. coli was observed to be more aggressive in surface colonization as compared to P. fragi. However, the spatial structure and microbial composition of mature dual-species biofilms were not observed to be significantly affected. Our findings also shed new light on the evidence that E. coli and P. fragi, respectively, enhanced their biofilm formation capabilities by upregulating expression level of genes that encoded Type 1 fimbriae and phosphate response regulator as dual-species consortia progressed, which could serve as a crucial factor that improved the difficulty of food biocontrol.


Assuntos
Pseudomonas fragi , Pseudomonas fragi/metabolismo , Escherichia coli/genética , Microbiologia de Alimentos , Carne/microbiologia , Biofilmes
4.
Food Microbiol ; 109: 104134, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309438

RESUMO

An enterocin whey solution, obtained by growing Enterococcus faecalis L2B21K3 and L3A21K6 in sweet whey - enterocin whey solution (EWS), was incorporated into gelatin/glycerol films that were tested for the control of Listeria monocytogenes. The films containing enterocins produced by either strain (EWS L2 and EWS K6 films) were shown to serve as a suitable matrix for bacteriocin release, preserve the anti-listerial activity for up to 90 days. When applied in cheese, EWS L2 and EWS K6 films were able to reduce L. monocytogenes contamination to undetected levels after 20 or 30 days, respectively, and prevented the migration of this pathogen from the films to cheese. The incorporation of EWS into films did not affect (p < 0.05) moisture content, solubility, permeability (water vapor and limonene), and elongation at break compared to control films (without EWS). However, thickness, swelling index and tensile strength were higher (p < 0.05) in EWS films. These results suggest that active EWS gelatin/glycerol films could be an effective, and safe application to control L. monocytogenes in cheese. In addition, the use of cheese whey as a culture medium for the production of the bacteriocins complemented with the incorporation in films formulation as a packaging material represents an alternative approach to reuse this by-product of cheese production.


Assuntos
Bacteriocinas , Queijo , Listeria monocytogenes , Soro do Leite , Gelatina , Glicerol/farmacologia , Microbiologia de Alimentos , Bacteriocinas/farmacologia
5.
Food Microbiol ; 109: 104139, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309441

RESUMO

The trend of feeding dogs and cats with raw pet food claiming health benefits poses health concerns due to the occurrence of pathogenic bacteria. High pressure processing (HPP) allows the non-thermal inactivation of microorganisms, preserving the nutritional characteristics with minimal impact on organoleptic traits of food. The present study aimed to evaluate and model the effect of HPP application (450-750 MPa for 0-7 min) on the inactivation of Salmonella, endogenous microbiota and colour of raw pet food formulated with different concentrations of lactic acid (0-7.2 g/kg) as natural antimicrobial. Additionally, the effect of a subsequent frozen storage of pressurized product was assessed. Salmonella inactivation ranged between 1 and 9 log, depending on the combination of conditions. According to the polynomial model obtained, the effect of pressure was linear, while a quadratic term was also included for holding time (depicting the occurrence of a resistant tail at ca. 4-6 min). The effect of lactic acid was dependent on the pressure level, being most relevant for treatments below 600 MPa. Frozen storage after HPP prevented the pathogen recovery and caused a further Salmonella inactivation enhanced by lactic acid in most of the treatments. Endogenous microbial groups were significantly reduced by HPP to below the detection level in several conditions. In general, little effect of HPP on the instrumental colour parameters was observed, except for a slight increase in lightness, which was hardly appreciable from visual observation. High pressure processing emerges as a relevant technology for the control of Salmonella spp. and to manage the microbiological safety of raw pet food. The mathematical model can be used as decision support tool to design safer raw pet food, while keeping the desired freshness appearance of the products.


Assuntos
Doenças do Gato , Doenças do Cão , Animais , Gatos , Cães , Microbiologia de Alimentos , Manipulação de Alimentos , Contagem de Colônia Microbiana , Salmonella/fisiologia , Ácido Láctico/farmacologia , Pressão Hidrostática
6.
Food Microbiol ; 109: 104147, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309446

RESUMO

Vacuum packaging and storage conditions at chilled temperatures are commonly used in order to prolong the shelf life of meat. Under these conditions and time-temperature abuse, cold-tolerant (facultatively) anaerobic spoilage microorganisms can continue growing. This study investigated growth of six relevant spoilage microorganisms in vacuum-packed beef (n = 12, 72 subsamples, stored at 10 °C for 28 days) using culture and qPCR methods. Correspondingly, six qPCRs were newly developed/modified (for total bacteria, lactic acid bacteria (LAB), Enterobacterales, total fungi, Kazachstania psychrophila, and cold-tolerant Clostridium spp.). Besides microbial quantification, four spoilage appearances of meat (gas production, spoilage odor, % drip loss, and meat color) were observed. Results obtained from culture and qPCR show that total bacteria, LAB, and Enterobacterales reached their stationary phase at day 7 when spoilage parameters such as gas production were statistically increased and a deviation of odor was detected. Fastidious cold-tolerant Clostridium spp. and K. psychrophila could be detected from day 7. Based on microbiological and sensory analysis results, the maximum shelf life of vacuum-packed beef stored at 10 °C is 7 days. The developed qPCR has the potential to be used as an alternative method to culturing for determination of microbial growth.


Assuntos
Contaminação de Alimentos , Embalagem de Alimentos , Animais , Bovinos , Vácuo , Embalagem de Alimentos/métodos , Temperatura , Contaminação de Alimentos/análise , Carne/microbiologia , Bactérias/genética , Microbiologia de Alimentos
7.
Food Microbiol ; 109: 104148, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309447

RESUMO

Despite increasing interest to investigate horizontal gene transfer as a leading cause of antibiotic resistance spread, the resistome is not only influenced by the influx and efflux of genes in different environments. Rather, the expression of existing genes under different stress conditions requires special attention. This study determined whether pre-adapting Lactiplantibacillus pentosus strains, isolated from Aloreña green table olives, to vegetable-based edible oils influence their phenotypic and genotypic responses to antibiotics. This has significant diet, food matrix, gut health, and food safety concerns. Pre-adapting L. pentosus strains to oils significantly changed their susceptibility profile to antibiotics. However, results generally differed among the three strains; although changes in the Minimum Inhibitory Concentration (MIC) of antibiotics occurred, it depended on the L. pentosus strain and the oil used for adaptation. The pre-adaptation of L. pentosus strains with olive, sunflower, argan and linseed oils induced gene expressions (e.g., rpsL, recA and uvrB) in several stress responses. Thus, to analyze this fact in-depth, transcriptional changes were reported in the selected potential probiotic L. pentosus CF2-10 adapted with olive or sunflower, rerouting its metabolic pathways to export toxic molecules through efflux pumps and ABC transporters. Pre-adaptation of some lactobacilli with olive or sunflower oils may represent a novel approach for manufacturing probiotic products with improved stability, functionality and robustness.


Assuntos
Lactobacillus pentosus , Olea , Probióticos , Microbiologia de Alimentos , Fermentação , Lactobacillus pentosus/metabolismo , Probióticos/metabolismo , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Óleos
8.
Food Microbiol ; 109: 104143, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309444

RESUMO

The objective of the present study was to compare the growth of food-pathogens Listeria monocytogenes, Salmonella enterica, food spoilage Bacillus subtilis, an industrial milk product isolate, and spore-forming Paenibacillus in commercially available ultrahigh temperature processed (UHT) bovine milk and non-dairy, plant-based beverages (coconut, almond, cashew) stored at chilled and ambient temperatures (4 °C, 8 °C or 20 °C). Beverage samples were inoculated with a strain cocktail or individual strains of either Listeria or Salmonella, or Paenibacillus or Bacillus, respectively (approximately 1 × 103 CFU/mL). The findings indicate that the bacterial strains used in the study were capable of proliferating in plant-based beverages at higher rates than in bovine milk at 8 °C and 20 °C for Listeria and 20 °C for Salmonella and Paenibacillus, respectively. Bacillus subtilis grew equally fast in bovine milk and plant-based almond drink at 20 °C. No statistically significant difference (p > 0.05) in growth rates between different types of tested beverages was observed at 4 °C and at 8 °C for Listeria and Salmonella cocktails, respectively. These data suggest that plant-based beverages may present a significant risk for listeriosis and salmonellosis and post-opening recommendations should be carefully considered.


Assuntos
Bacillus , Listeria monocytogenes , Listeria , Paenibacillus , Animais , Leite/microbiologia , Microbiologia de Alimentos , Contagem de Colônia Microbiana , Esporos Bacterianos , Salmonella
9.
Food Microbiol ; 109: 104155, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309451

RESUMO

Some water disinfection treatments, such as chlorine and chlorine dioxide, used in the fresh-cut industry to maintain the microbiological quality of process water (PW), inactivate bacterial cells in the water but they also lead to the induction of an intermediate state between viable and non-viable known as viable but non-culturable (VBNC) state. Viable cells can participate in cross-contamination events but the significance of VBNC cells in PW, transfer to the product and potential resuscitation capacity during storage is unclear. The present study aims to determine first, if VBNC cells present in PW can cross-contaminate leafy greens during washing and secondly its potential revival during shelf-life. Process water characterized by a high chemical oxygen demand, due to the presence of high levels of organic matter, was inoculated with Listeria monocytogenes or Escherichia coli O157:H7. Inoculated PW was then treated for 1 min with chlorine dioxide (3 mg/L) or chlorine (5 mg/L) to generate VBNC cells. Absence of culturable cells was confirmed by plate count and VBNC cells by viability quantitative polymerase chain reaction (v-qPCR) complemented with two dyes, ethidium (EMA) and propidium (PMAxx) monoazide. Cross-contamination of shredded lettuce was demonstrated by monitoring the VBNC cells after washing the product for 1 min in the contaminated PW and during shelf life (15 days at 7 °C). In the case of L. monocytogenes, considering the total concentration of L. monocytogenes VBNC cells present in the PW, only a low proportion of cells were able to cross-contaminate the product during washing. VBNC L. monocytogenes cells were able to resuscitate on the product during shelf life, although levels of cultivable bacteria, close to the limit if detection (0.7 ± 0.0 log CFU/g), were only detected at the end of storage. On the other hand, VBNC cells of E. coli O157:H7 present in PW were not able to cross-contaminate shredded lettuce during washing. Moreover, when shredded lettuce was artificially inoculated with VBNC E. coli O157:H7, resuscitation of the VBNC cells during storage (15 days at 7 °C) was not observed. Based on the results obtained, injured L. monocytogenes cells present in the PW are able to be transferred to the product during washing. If VBNC L. monocytogenes cells present in leafy greens (shredded lettuce and baby spinach), they can resuscitate, although cultivable numbers remained very low. Taking all the results together, it could be concluded that under industrial conditions, VBNC cells can be transferred from water to product during washing, but their capacity to resuscitate in the leafy greens during storage is low.


Assuntos
Escherichia coli O157 , Listeria monocytogenes , Cloro/farmacologia , Cloro/análise , Manipulação de Alimentos/métodos , Contaminação de Alimentos/prevenção & controle , Contaminação de Alimentos/análise , Alface/microbiologia , Água/análise , Contagem de Colônia Microbiana , Microbiologia de Alimentos
10.
Food Microbiol ; 109: 104150, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309452

RESUMO

Routine monitoring of foodborne pathogens such as Listeria monocytogenes in food processing environments are time-consuming necessities to ensure food safety. Alternative rapid diagnostic methods for pathogen detection are increasingly used, but often demand specialized equipment, making them unsuitable for on-site testing. This short communication describes the successful demonstration of combining the sample preparation method Matrix-Lysis with a chemiluminescent based detection platform (AquaSpark™) for detection of L. monocytogenes in milk and yogurt. The proposed method was evaluated against qPCR resulting in 100% relative specificity for both foodstuffs and a relative sensitivity of 100% for milk as well as 96% for yogurt for bacterial levels >1 CFU/ml. Only at very low initial bacterial concentrations (<1 CFU/ml) diverging results were found highlighting the advantages and limitations of both methods. While being less susceptible to contamination and false positive results from non-growing or dead cells, qPCR had a slightly lower overall detection limit. However, it has to be pointed out that qPCR has an increased analytical cost and also requires an additional 24 h analysis time. This study demonstrates the first successful application of a chemilumonogenic detection approach for L. monocytogenes in food that has a high potential for on-site testing.


Assuntos
Listeria monocytogenes , Animais , Listeria monocytogenes/genética , Microbiologia de Alimentos , Laticínios/microbiologia , Leite/microbiologia , Reação em Cadeia da Polimerase em Tempo Real , Iogurte
11.
Food Microbiol ; 109: 104125, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309454

RESUMO

Foodborne pathogenic bacteria in multi-species biofilms in food manufacturing facilities have been suspected to be the cause of cross-contamination leading to foodborne illness. We studied if cafeteria kitchen-associated bacterial isolates can have any protective effect on E. coli O157:H7 in biofilm against extracellular polymeric substances (EPS)-degrading enzymes and sodium hypochlorite. We investigated multi-species biofilm-forming ability and the efficacy of EPS-degrading enzymes using crystal violet assay. The susceptibility of E. coli O157:H7 to sodium hypochlorite (NaClO) was evaluated using propidium monoazide combined with quantitative PCR (PMA-qPCR). Then, a combined treatment with enzymes followed by NaClO was also tested. Most cafeteria kitchen isolates of Acinetobacter and Bacillus were able to form biofilms. Several of them showed a protective effect on E. coli O157:H7 against NaClO after forming multi-species biofilms, particularly in Acinetobacter. This protective effect on E. coli O157:H7 was also noticed after the enzyme or the combined treatment with NaClO. Our results give us an insight into the protective role of food-associated environmental bacteria for E. coli O157:H7 in biofilms against common sanitizers and warrant further study to develop effective control methods. Our study also highlights the importance of preventing contamination or biofilm formation by environmental microorganisms, eventually reducing foodborne illness.


Assuntos
Acinetobacter , Bacillus , Escherichia coli O157 , Doenças Transmitidas por Alimentos , Humanos , Hipoclorito de Sódio/farmacologia , Microbiologia de Alimentos , Biofilmes , Doenças Transmitidas por Alimentos/prevenção & controle , Matriz Extracelular
12.
Food Microbiol ; 109: 104123, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309453

RESUMO

Biofilms serve as a reservoir for pathogenic and spoilage microorganisms, and their removal from different surfaces is a recurring problem in the beverage industry. This study aimed to investigate the effect of a combination of natamycin (NAT, 0.01 mmol/l) and farnesol (FAR, 0.6 mmol/l) against biofilms on ultrafiltration (UF) membranes and stainless steel (SS) surfaces using apple juice as food matrix. The co-adhesion of Rhodotorula mucilaginosa, Candida tropicalis, C. krusei and C. kefyr (mixed-yeast) with Listeria monocytogenes, Salmonella enterica or Escherichia coli O157:H7 (multi-species) in presence of NAT + FAR was evaluated for 2, 24, 48 h. In biofilms treated with NAT + FAR were observed by cell quantification and microscopy, inhibition of the filamentous yeast forms, disruption of the tri-dimensional structure and a high detachment of yeast cells. NAT + FAR affected the biofilms independently of the surfaces used and the presence (or not) of bacteria. L. monocytogenes was the most susceptible (p < 0.001) in multi-species biofilms, followed by E. coli O157:H7 on both surfaces (p < 0.001), whereas the growth of S. enterica was reduced (p < 0.05) in SS but not in UF-membranes (p > 0.05). Since the combination NAT + FAR affected the structure and viability of yeast species and foodborne pathogens in multi-species biofilms developed on UF-membranes and SS surfaces, the combination proposed could be considered a promising control agent to prevent biofilms in apple juice processing lines.


Assuntos
Escherichia coli O157 , Listeria monocytogenes , Malus , Farneseno Álcool/farmacologia , Malus/microbiologia , Natamicina/farmacologia , Microbiologia de Alimentos , Aço Inoxidável , Leveduras , Biofilmes , Contagem de Colônia Microbiana
13.
Food Chem ; 402: 134488, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36303370

RESUMO

Lactobacillus plantarum NR1-7, Bifidobacteriµm animalis subsp. lactis BZ11 and Candida utilis RY were selected as specific starter cultures to ferment Hong Suan Tang (HST), a traditional hot and sour soup of southwest China made from tomatoes and red peppers. The fermentation conditions were optimized with response surface methodology (RSM). The changes in the physicochemical index, flavor quality, organic acids, and bioactive substances were evaluated. The results showed that the mixed starter fermented HST was quickly acidified, promoting product maturity and significantly reducing the nitrite content, which shortened the fermentation time and improved product safety. Moreover, lactic acid concentration was significantly increased, about 3 times higher than the control group. Sixteen compounds were confirmed to be the critical aroma-active compounds present in the HST. Furthermore, mixed inoculation improved the content of bioactive substances by lowering their degradation. This research sets the basis for the standardized production of HST products.


Assuntos
Bifidobacterium animalis , Lactobacillus plantarum , Fermentação , Lactobacillus plantarum/metabolismo , Microbiologia de Alimentos , Candida
14.
Food Chem ; 402: 134182, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36126574

RESUMO

In this work, the synergistic/antagonistic impact of glucose and mixed starter cultures, namely Latilactobacillus sakei, Pediococcus pentosaceus, and Staphylococcus xylosus, was evaluated in Italian salami in terms of metabolomics and sensory profiles. As expected, Salami manufactured with 0.5 % glucose exhibited a substantial pH drop, showing values close to 5 at 12 days of ripening. Metabolomics revealed 1841 metabolites, mainly belonging to amino acids, peptides, glycerolipids, and nucleic acids, showing a greater hierarchical role of glucose addition when compared with inoculated microbial starters. Distinct metabolomic fingerprints could be observed across treatments, mainly concerning glutamyl peptides like gamma-glutamyl-glutamate (related to the kokumi taste), biogenic amines (spermine), and lipid oxidation products (i.e., the oxylipin 13S-hydroperoxylinolenic acid). Such differences may drive the differences in sensory profiles recorded among treatments. These findings indicate the need to select ad-hoc starter cultures to improve the safety, quality, and sensory traits of salami.


Assuntos
Produtos da Carne , Ácidos Nucleicos , Microbiologia de Alimentos , Espermina , Oxilipinas , Fermentação , Produtos da Carne/análise , Aminas Biogênicas/metabolismo , Aminoácidos/metabolismo , Peptídeos/metabolismo , Glucose , Glutamatos/metabolismo
15.
Food Chem ; 402: 134300, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36152558

RESUMO

The effect of convective hot air and vacuum drying alone and combined with germination on alfalfa seeds' proximate composition, techno-functional, thermal and structural properties was investigated. Corresponding properties of treated alfalfa samples were compared with those of commercially available alfalfa sprouts. Both drying and combined germination and drying treatments resulted in increased carbohydrates (41.99-48.82 %), TDF (10.51-12.51 %) and Mg contents (789.49-2119.24 mg/kg), while the reduction in ash, lipid and Fe content compared to raw alfalfa seeds was observed. Alfalfa seeds subjected to combined germination and drying treatment exhibited higher water and oil binding capacities, as well as emulsions with smaller volume mean droplet diameters compared to the raw and dried samples. Conducted treatments resulted in greater thermal stability of globulins and a slight decrease in crystallinity index, although alfalfa seeds' structure did not change significantly according to FTIR analysis. Differences in applied drying techniques on alfalfa seeds' properties were not observed.


Assuntos
Microbiologia de Alimentos , Medicago sativa , Vácuo , Contagem de Colônia Microbiana , Sementes , Água/química , Lipídeos/farmacologia , Carboidratos , Germinação
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121830, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36179567

RESUMO

Rapid, sensitive and simultaneous detection of multiple bacteria in foodborne is still a major challenge in public health field. Here, a fluorescence immunoassay that can achieve high-throughput detection of three Gram-positive foodborne pathogenic bacteria simultaneously was proposed. Vancomycin and bovine serum albumin conjugate (Van-BSA) was immobilized on a polycarbonate chip to capture three Gram-positive foodborne pathogenic bacteria, Staphylococcus aureus (S. aureus), Bacillus cereus (B. cereus) and Listeria monocytogenes (L. monocytogenes). CdSe/ZnS quantum dot modified antibodies (Ab-QD) were prepared by carbodiimide coupling chemistry. Due to the affinity reaction between antibodies and proteins on the bacterial surface, the simultaneous detection of multiple Gram-positive bacteria was achieved by monitoring the fluorescence signal of quantum dot by a portable microfluidic chip analyzer. Under optimal conditions, low detection limits was 18 CFU/well, 3 CFU/well and 36 CFU/well for S. aureus, B. cereus and L. monocytogenes, respectively. With satisfactory accuracy and precision, the proposed fluorescence immunoassay holds good prospects to detect pathogens in real food samples.


Assuntos
Listeria monocytogenes , Infecções Estafilocócicas , Humanos , Animais , Leite , Microbiologia de Alimentos , Staphylococcus aureus , Imunoensaio
17.
Meat Sci ; 195: 109020, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36334510

RESUMO

The present study evaluated the effect of Coreopsis tinctoria Nutt. essential oil (CEO) and its microcapsules (CEOM) on the accumulation of biogenic amines (BAs) and the quality of smoked horsemeat sausage during fermentation. The results showed that CEO could effectively inhibit Enterobacteriaceae growth and the formation of BAs (cadaverine, putrescine, tyrosine, histamine and tryptamine) in smoked horsemeat sausages, and the inhibition of CEO was enhanced after embedding (P < 0.05). Compared with other groups, thiobarbituric acid reactive substances, total volatile basic nitrogen and pH were lower in the microcapsule group. Furthermore, the sensory evaluation indicated that the addition of CEOM was a more effective way to maintain color and delay the deterioration of the sensory quality of sausages. Therefore, it is suggested that the CEOM can be used as a natural preservative in traditional fermented meat products to inhibit BAs accumulation and improve quality.


Assuntos
Coreopsis , Produtos da Carne , Óleos Voláteis , Produtos da Carne/análise , Cápsulas , Fumaça , Microbiologia de Alimentos , Aminas Biogênicas/análise , Fermentação
18.
Meat Sci ; 195: 109019, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36335867

RESUMO

This study aimed to explore the effects of different levels (0, 8, and 12 kGy) of low-energy electron beam (LEEB; 0.2 MeV) on the quality and shelf-life of vacuum-packaged pork stored under chilled and superchilled conditions for 30 days. LEEB irradiation promoted lipid and protein oxidation, regardless of the levels used. Combined 8 kGy LEEB irradiation with superchilled storage significantly elevated a* values and preserved acceptable sensory characteristics of pork until day 30, unlike the other treatment combinations. This synergistic treatment also significantly reduced total viable counts and total volatile basic nitrogen contents, and thus extended the shelf-life of vacuum-packaged pork to >30 days, which may be due to the antibacterial effects on Photobacterium, Carnobacterium and Lactobacillus. In conclusion, it is recommended that the 8 kGy LEEB irradiation level be applied to pork and that it should be used in combination with superchilled storage to preserve meat quality and extend the shelf-life of vacuum-packaged pork.


Assuntos
Carne de Porco , Carne Vermelha , Animais , Suínos , Vácuo , Embalagem de Alimentos , Carne Vermelha/microbiologia , Microbiologia de Alimentos , Elétrons
19.
Int J Food Microbiol ; 384: 109959, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36257183

RESUMO

This study evaluated the survival of Listeria monocytogenes on fresh-cut melon and papaya treated with citral nanoemulsion (CN) during 7 days of storage at 4, 8, 12, and 16 °C. CN was prepared by catastrophic phase inversion, and fresh-cut melon and papaya were artificially inoculated, resulting in 5 log cfu/g of L. monocytogenes. Then, they were treated with 0.30 (CN-0.3) and 0.15 (CN-0.15) µL/mL of CN. CN presented droplet size below 200 nm, monodisperse distribution, and negative surface charge. CN-0.3 reduced the L. monocytogenes counts more efficiently, with counts below the detection limit (1 log cfu/g) in both fruits after 48 h at 4 °C, and 72 h at 8 °C and 12 °C. At 16 °C, L. monocytogenes counts were below the detection limit for CN-0.3 after 120 h in papaya, but it survived the other treatments for 7 days. Both CN-0.3 and CN-0.15 decreased the indigenous microbiota. Scanning electron microscopy (SEM) showed bubbles in L. monocytogenes membrane and cell disruption in fruits treated with CN-0.3. Finally, CN-0.3 treated melon and papaya showed greater brightness, herbal flavor and aroma, firmness, and juiciness, as well as lower sugar and organic acid profile changes than the control samples during storage. Results indicate citral nanoemulsion's efficiency in controlling L. monocytogenes growth on fresh-cut melon and papaya stored at refrigerated temperatures without negatively influencing the sensory parameters.


Assuntos
Carica , Cucurbitaceae , Listeria monocytogenes , Microbiologia de Alimentos , Manipulação de Alimentos/métodos , Temperatura , Verduras , Contagem de Colônia Microbiana
20.
Int J Food Microbiol ; 384: 109975, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36257184

RESUMO

Sprouts have been involved in many outbreaks of salmonellosis where seeds were identified as the likely source of contamination. This study aimed to develop an effective heat treatment that could achieve a >5-log reduction of Salmonella inoculated on alfalfa seeds while maintaining seed viability and vigor. Effects of seeds' water activity (aw) and heat treatment temperature on Salmonella inactivation and seed viability were determined. Alfalfa seeds were dip-inoculated with a four-strain Salmonella cocktail and dried to aw of 0.05-0.20. The inoculated seeds were then placed in sealed glass tubes and heated at 65.9, 71.0, and 76.6 °C for up to 180 h. Increasing aw of seeds greatly improved thermal inactivation of Salmonella. For example, to achieve a >5-log reduction of Salmonella on seeds, treatment times of 140 and 60 h at 71.0 °C were required for aw of 0.1 and 0.2, respectively. Treatment temperature also greatly affected inactivation of Salmonella on alfalfa seeds. For example, to achieve a >5-log reduction of Salmonella on seeds with aw of 0.2, treatment times of 180 and 60 h were required for temperatures of 65.9 and 71.0 °C, respectively. Seeds' aw was critical for preserving seed viability. When seeds were treated at 71.0 °C for 60 h, increasing aw from 0.1 to 0.2 decreased the sprout yield ratio from 103.9 % to 73.7 %. Treatment of seeds with aw of 0.1 at 71.0 °C was found to be optimum for achieving a desirable Salmonella inactivation level while maintaining seed viability, resulting in 4.2 and 6.0 log reductions of Salmonella and yield ratios of 100.7 % and 96.1 % after 100- and 140-h treatments, respectively. This optimum heat treatment was compared with the traditional 20,000-ppm chlorine wash in terms of Salmonella inactivation and preservation of seed viability and found to be a far superior disinfection method. The chlorine treatment achieved 1.8 and 2.0 log reductions of Salmonella and yield ratios of 70.9 % and 65.1 % after 15- and 20-min treatments, respectively.


Assuntos
Medicago sativa , Água , Temperatura , Água/farmacologia , Cloro/farmacologia , Calefação , Contagem de Colônia Microbiana , Salmonella , Sementes , Microbiologia de Alimentos
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