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1.
Water Res ; 189: 116638, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33221584

RESUMEN

Vibrio parahaemolyticus (V.p) is an epidemiologically significant pathogen that thrives in coastal waters where oysters are harvested, posing high risks to human health and shellfish industry and requiring effective forecasting models for emergency preparedness and interventions. This study sought to develop forecasting models with differing lead times, which are able to predict the level of V.p in oysters in advance to mitigate the health risk to the general public and the economic loss to the shellfish industry. The Random Forest method along with 227 sampling datasets from two different geographic locations were utilized to: (1) Identify the most critical environmental predictors controlling the level of V.p in oysters, (2) Select the most important time lags for the environmental predictors as model input variables, and (3) Develop four forecasting models (RF-1Day, RF-2Day, RF-3Day, and RF-4Day) with the lead time of one to four days. The uncertainty involved in model predictions was quantified using the bootstrapping method. Results showed that V.p abundance in oysters is controlled by antecedent environmental conditions 1-11 days before. The antecedent environmental conditions can be described using time-lagged Sea Surface Temperature (SST) and salinity. The V.p abundance can well be forecasted 1 - 4 days in advance using the four models. The performance of the models decreases with increasing lead time. The RF-3Day and RF-4Day models can be employed primarily for emergency preparedness due to their relatively long lead time while the RF-1Day and RF-2Day models can be used primarily for management interventions due to their relatively high predictive performance.


Asunto(s)
Ostreidae , Vibrio parahaemolyticus , Animales , Recuento de Colonia Microbiana , Humanos , Salinidad , Mariscos , Temperatura
2.
J Appl Microbiol ; 130(1): 133-141, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32219941

RESUMEN

AIMS: The purpose of this experiment was to study the bacterial diversity of traditional fermented sausages from four typical regions of China (Chengdu, Shenzhen, Changsha and Harbin) and to further evaluate their microbiological safety. METHODS AND RESULTS: The diversity of the microbiota of the sausages was studied using the Illumina HiSeq platform. The results showed that compared with the highest diversity of fermented bacteria in Guangdong, the bacterial diversity of fermented sausage was the lowest in Sichuan. The percentage of dominant phylum (Firmicutes, Cyanophyta, Proteobacter) were 78·39, 13·13 and 7·14% in SC, 35·47, 30·36 and 28·04% in GD, 54·81, 28·91 and 14·00% in HN, 20·20, 58·16 and 17·31% in HB respectively. The main genus distribution of fermented sausages in different regions is varied, but lactic acid bacteria and cyanobacteria are generally the main ones. Traditional fermented sausages using natural fermentation methods have poor microbiological safety, and pathogenic and spoilage micro-organisms such as Acinetobacter, Brochothrix and Pseudomonas have been detected in all four regions. CONCLUSIONS: The results in this paper provide a microbiota profile of four typical fermented sausages in China. There is a big difference in the microbiota of sausages in different regions, and the good flavour of traditional Chinese fermented sausage is related closely with the abundant microbial resources, however, the natural fermentation method also expose to the product security threats, including spoilage, pathogenic micro-organisms and biogenic amines, etc. SIGNIFICANCE AND IMPACT OF THE STUDY: The results would offer guidance for industrial fermented sausage production with certain flavour and also improve the microbial resource utilization, and contribute to the control of harmful micro-organisms in traditional fermented sausage.


Asunto(s)
Alimentos y Bebidas Fermentados/microbiología , Productos de la Carne/microbiología , Microbiota , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bacterias/metabolismo , China , Recuento de Colonia Microbiana , Fermentación , Microbiología de Alimentos , Inocuidad de los Alimentos , Gusto
3.
Int J Food Microbiol ; 337: 108928, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33152572

RESUMEN

Sponges are frequently used in kitchens and have been shown to harbor large numbers of bacteria, occasionally also pathogens. Less is known about kitchen brushes regarding usage and presence of bacteria. In the present study, the use of sponges and brushes was studied in a survey among 9966 European consumers in ten countries, and growth and survival of bacteria in sponges and brushes were examined in laboratory experiments. Sponges were the preferred hand-cleaning utensils for washing-up in the majority of countries, while brushes were most frequently used in Denmark and Norway. Consumers mostly change their sponges at regular times, but also sensory cues (looks dirty, smelly, slimy) and usage occurrences such as wiping up meat juices may trigger replacement. Besides cleaning the dishes, over a quarter of the dish brush users also use it to clean a chopping board after soilage from chicken meat juices. The water uptake and drying rate varied considerably, both between different sponges and between brushes and sponges, where brushes dried fastest. Campylobacter survived one day in all sponges and Salmonella more than seven days in two of three types of sponges. In the type of sponge that dried slowest, Salmonella grew on the first day and was always found in higher levels than in the other sponges. Non-pathogenic bacteria grew in the sponges and reached levels around 9 log CFU/sponge. In brushes all types of bacteria died over time. Campylobacter and Salmonella were reduced by more than 2.5 log to below the detection limit after one and three days, respectively. Bacteriota studies revealed a tendency for a dominance by Gram-negative bacteria and a shift to high relative prevalence of Pseudomonas over time in sponges. Both enumeration by agar plating and bacteriota analysis confirmed that the pathogens were in a minority compared to the other bacteria. Treatments of sponges and brushes with chlorine, boiling or in the dishwasher were effective to reduce Salmonella. We conclude that brushes are more hygienic than sponges and that their use should be encouraged. Contaminated sponges or brushes should be replaced or cleaned when they may have been in contact with pathogenic microorganisms, e.g. used on raw food spills. Cleaning of sponges and brushes with chlorine, boiling or dishwasher may be a safe alternative to replacing them with new ones.


Asunto(s)
Fenómenos Fisiológicos Bacterianos , Contaminación de Equipos/estadística & datos numéricos , Productos Domésticos/microbiología , Animales , Bacterias/aislamiento & purificación , Campylobacter/fisiología , Cloro , Recuento de Colonia Microbiana , Comportamiento del Consumidor , Utensilios de Comida y Culinaria , Europa (Continente) , Manipulación de Alimentos , Higiene/normas , Carne/microbiología , Salmonella/fisiología , Factores de Tiempo
4.
Int J Food Microbiol ; 337: 108914, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33166913

RESUMEN

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.


Asunto(s)
Medios de Cultivo/química , Microbiología de Alimentos/métodos , Listeria monocytogenes/crecimiento & desarrollo , Recuento de Colonia Microbiana , Listeria monocytogenes/metabolismo
5.
Int J Food Microbiol ; 337: 108947, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33181419

RESUMEN

The objective of the study was to assess the antimicrobial effect of active essential oil components (EOs) namely (carvacrol (CA), cinnamaldehyde (CI) and thymol (TH)) on Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 in chicken tawook during storage at 4 and 10 °C. A marinade consisting of ingredients commonly used in the chicken tawook recipe was prepared and mixed with 1% and 2% v/v CA, CI or TH. The marinade with or without EOs was added to fresh chicken breast cubes inoculated with the foodborne pathogens. Afterward, marinated chicken "tawook" was stored at 4 and 10 °C covered with cling wrap to mimic chill and mild abuse storage conditions for up to 7 days. At 10 °C, the marinade decreased L. monocytogenes numbers on day 4 and 7 by about 2.4 log10 CFU/g as compared to unmarinated samples. Adding EOs to chicken tawook did not change L. monocytogenes numbers during storage at 4 and 10 °C. For Salmonella spp., the marinade decreased the numbers during 10 °C storage on day 4 and 7 by about 4.9 log10 CFU/g as compared to unmarinated samples. At 4 °C, EOs at 2% decreased Salmonella spp. on day 7 by 0.5 log10 CFU/g. One percent CI significantly decreased Salmonella by 1.5 log10 CFU/g, at day 4 of storage. At 10 °C, 1% CA, 2% CI, 1% and 2% TH decreased Salmonella spp. in the samples by 0.5 log10 CFU/g on day 7. The marinade decreased E. coli O157:H7 numbers on the chicken samples during 10 °C storage on day 4 and 7 by about 3.3 log10 CFU/g as compared to unmarinated samples. Regardless of storage day at 4 °C, EOs decreased E. coli O157:H7 populations in chicken tawook by ≤2.4 log10 CFU/g compared to samples without EOs, where the decrease was ≤1.4 log10 CFU/g. Moreover, no significant decrease in E. coli O157:H7 populations could be attributed to the addition of EOs in samples which were stored at 10 °C. Increasing the concentration of EOs from 1 to 2% seemed to have no significant effect in reducing the tested foodborne pathogen populations.


Asunto(s)
Antibacterianos/farmacología , Almacenamiento de Alimentos/métodos , Productos de la Carne/microbiología , Aceites Volátiles/farmacología , Animales , Pollos , Recuento de Colonia Microbiana , Escherichia coli O157/efectos de los fármacos , Escherichia coli O157/aislamiento & purificación , Microbiología de Alimentos , Listeria monocytogenes/efectos de los fármacos , Listeria monocytogenes/aislamiento & purificación , Salmonella/efectos de los fármacos , Salmonella/aislamiento & purificación , Temperatura
6.
Int J Food Microbiol ; 337: 108948, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33197682

RESUMEN

Novel processing methods such as cold atmospheric plasma (CAP) and natural antimicrobials like nisin, are of interest to replace traditional food decontamination approaches as, due to their mild nature, they can maintain desirable food characteristics, i.e., taste, texture, and nutritional content. However, the microbial growth characteristics (planktonic growth/surface colonies) and/or the food structure itself (liquid/solid surface) can impact the inactivation efficacy of these novel processing methods. More specifically, cells grown as colonies on a solid(like) surface experience a completely different growth environment to cells grown planktonically in liquid, and thus could display a different response to novel processing treatments through stress adaptation and/or cross protection mechanisms. The order in which combined treatments are applied could also impact their efficacy, especially if the mechanisms of action are complementary. This work presents a fundamental study on the efficacy of CAP and nisin, alone and combined, as affected by food system structure. More specifically, Listeria innocua was grown planktonically (liquid broth) or on a viscoelastic Xanthan gum gel system (1.5% w/v) and treated with CAP, nisin, or a combination of the two. Both the inactivation system, i.e., liquid versus solid(like) surface and the growth characteristics, i.e., planktonic versus colony growth, were shown to impact the treatment efficacy. The combination of nisin and CAP was more effective than individual treatments, but only when nisin was applied before the CAP treatment. This study provides insight into the environmental stress response/adaptation of L. innocua grown on structured systems in response to natural antimicrobials and novel processing technologies, and is a step towards the faster delivery of these food decontamination methods from the bench to the food industry.


Asunto(s)
Antibacterianos/farmacología , Manipulación de Alimentos/métodos , Listeria/efectos de los fármacos , Nisina/farmacología , Gases em Plasma/farmacología , Recuento de Colonia Microbiana , Microbiología de Alimentos , Listeria/crecimiento & desarrollo , Modelos Biológicos , Pasteurización/métodos
7.
Int J Food Microbiol ; 337: 108949, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33220648

RESUMEN

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.


Asunto(s)
Bacterias/aislamiento & purificación , Técnicas Bacteriológicas/métodos , Manipulación de Alimentos/estadística & datos numéricos , Microbiología de Alimentos , Malus/microbiología , Bacterias/clasificación , Recuento de Colonia Microbiana , Biomarcadores Ambientales , Microbiología de Alimentos/métodos , Microbiología de Alimentos/estadística & datos numéricos , Higiene , Prevalencia
8.
J Appl Microbiol ; 130(1): 157-164, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32623828

RESUMEN

AIMS: Several acidophilic bacteria have not been cultured, primarily owing to the lack of suitable culture methods under strong acidic conditions. This study aimed to quantitatively evaluate the strengths of the agar plates (AP) and gellan gum plates (GP), and optimal culture periods under strong acidic conditions. METHODS AND RESULTS: To define the lower limit of plate strength for bacterial isolation culture, the diameter of Escherichia coli K12 colonies and the breaking stress of plates at different concentrations of gelling agents, medium composition and pH conditions were determined. The lower limit of available strength of AP and GP was 19·6 and 14·8 kPa, respectively. Medium composition slightly affected AP breaking stress, although GP with a high cationic concentration medium could not be prepared. CONCLUSIONS: Assessment of the strength limits of AP and GP revealed that AP is not suitable for prolonged bacterial culture (≥72 h). Furthermore, GP was completely ineffective for bacterial culture under highly acidic conditions (≤pH 1·0). SIGNIFICANCE AND IMPACT OF THE STUDY: Our quantitative evaluation method based on breaking stress is a potentially valuable tool to understand the state and the suitable limit of plate culture methods in more detail under various conditions.


Asunto(s)
Agar/química , Bacterias/aislamiento & purificación , Recuento de Colonia Microbiana/métodos , Medios de Cultivo/química , Polisacáridos Bacterianos/química , Bacterias/crecimiento & desarrollo , Concentración de Iones de Hidrógeno , Estrés Mecánico
9.
Int J Food Microbiol ; 336: 108895, 2021 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-33075693

RESUMEN

Fresh Atlantic salmon (Salmo salar) represents a healthy, nutritious food with global distribution and increasing consumption and economic value. Contaminating Listeria monocytogenes in fresh salmon represents a health hazard to consumers, is linked to extensive product recalls and is a major challenge for salmon processors. Verdad N6, a commercially available buffered vinegar, was evaluated as a treatment for raw salmon fillets either alone or in combination with the antimicrobial peptide nisin, with regard to anti-listerial effects under processing and storage, and influence on sensory quality and background microbiota. Salmon fillets were surface contaminated with L. monocytogenes and immersed in solutions of Verdad N6 or treated with nisin or a combination of these two treatments. Levels of L. monocytogenes were determined during vacuum-pack refrigerated storage. The use of Verdad N6 resulted in increased lag times and substantially reduced growth of L. monocytogenes. The inhibitory effects were dependent on Verdad N6 levels, immersion time, and storage time and temperature. A 5 s immersion in 10% Verdad N6 solution at 4 °C reduced growth of L. monocytogenes from log 2.8 to log 1 after 12 days of storage. Nisin (0.2-1 ppm) had listericidal effects up to 1 log but did not inhibit regrowth when used alone. Appropriate combinations of Verdad N6 and nisin led to L. monocytogenes levels no higher after 12 days of storage than the initial levels. The inhibitory effects were markedly lower at 7 °C than at 4 °C. Salmon with Verdad N6 showed reduced levels of total counts during storage indicating a longer shelf-life, and a shift in the dominating bacteria with reduced and increased relative levels of Enterobacteriaceae and lactic acid bacteria, respectively. Sensory analyses of raw and cooked Verdad N6 treated a non-treated salmon resulted in small differences. In summary, Verdad N6 is an option for production of high-quality raw salmon with increased shelf-life and enhanced food safety through its Listeria inhibiting effects. The application of Verdad N6 in combination with nisin treatment can further reduce the listeria-risks of these products.


Asunto(s)
Almacenamiento de Alimentos/métodos , Listeria monocytogenes/efectos de los fármacos , Nisina/farmacología , Ácido Acético/farmacología , Animales , Antibacterianos/farmacología , Recuento de Colonia Microbiana , Microbiología de Alimentos , Alimentos Crudos/microbiología , Salmo salar , Alimentos Marinos/microbiología , Vacio
10.
Sci Total Environ ; 752: 141705, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-32892039

RESUMEN

E. coli survival in biosolids storage may present a risk of non-compliance with guidelines designed to ensure a quality product safe for agricultural use. The storage environment may affect E. coli survival but presently, storage characteristics are not well profiled. Typically biosolids storage environments are not actively controlled or monitored to support increased product quality or improved microbial compliance. This two-phased study aimed to identify the environmental factors that control bacterial concentrations through a long term, controlled monitoring study (phase 1) and a field-scale demonstration trial modifying precursors to bacterial growth (phase 2). Digested and dewatered biosolids were stored in operational-scale stockpiles to elucidate factors controlling E. coli dynamics. E. coli concentrations, stockpile dry solids, temperature, redox and ambient weather data were monitored. Results from ANCOVA analysis showed statistically significant (p < 0.05) E. coli reductions across storage periods with greater die-off in summer months. Stockpile temperature had a statistically significant effect on E. coli survival. A 4.5 Log reduction was measured in summer (maximum temperature 31 °C). In the phase 2 modification trials, covered stockpiles were able to maintain a temperature >25 °C for a 28 day period and achieved a 3.7 Log E. coli reduction. In winter months E. coli suppression was limited with concentrations >6 Log10 CFU g-1 DS maintained. The ANCOVA analysis has identified the significant role that physical environmental factors, such as stockpile temperature, has on E. coli dynamics and the opportunities for control.


Asunto(s)
Escherichia coli , Aguas del Alcantarillado , Agricultura , Bacterias , Biosólidos , Recuento de Colonia Microbiana , Temperatura
11.
Int J Food Microbiol ; 336: 108904, 2021 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-33129004

RESUMEN

The aim of the present study was to determine the effects of organic fruit vinegars (blackberry, pomegranate, rosehip, and grape) used as marination liquids (MLs) on food-borne pathogens inoculated on beef, as well as on the quality characteristics (physical, chemical, microbiological and sensory properties) of beef during marination process at 4 °C for 24 h. In the first part of the study, meat samples separately inoculated with Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli O157:H7 (≅6 log CFU/mL) were marinated in four different MLs and the count of S. Typhimurium, L. monocytogenes and E. coli O157:H7 on samples decreased in the range of 1.040-1.225, 1.420-1.913 and 1.232-1.435 log CFU/g, respectively. Marination with rosehip vinegar (MLR) was determined as the most effective treatment against all pathogens. In the second part of the study, proximate composition, color parameters, cooking yield, marinate absorption, pH, texture profile, aerobic plate count and sensory properties of marinated meat samples were determined. The moisture content of the samples marinated with grape vinegar (MLG) (73.50%) was found lower than of the samples marinated with other formulations (in the range of 75.95-76.65%) (P < 0.05). Marination by various MLs resulted in significant differences between the L*, a* and b* values of meat samples (P < 0.05). The hardness value of the samples was decreased by marination with MLR (P < 0.05) and was determined as 25.70 N. There were no significant differences between the meat samples marinated with the four different MLs in terms of cooking yield, marinate absorption and pH (P > 0.05). Aerobic plate count was reduced in the range of 0.589-0.950 log CFU/g for 24 h marination (P > 0.05). The highest sensory evaluation scores in terms of flavor were determined in meat samples marinated with MLG (P > 0.05). Therefore, different fruit vinegars used as MLs improved the safety and quality of meat at different levels.


Asunto(s)
Ácido Acético/farmacología , Culinaria/métodos , Manipulación de Alimentos/métodos , Inocuidad de los Alimentos , Frutas/química , Ácido Acético/química , Animales , Bovinos , Recuento de Colonia Microbiana , Escherichia coli O157/efectos de los fármacos , Manipulación de Alimentos/normas , Microbiología de Alimentos , Listeria monocytogenes/efectos de los fármacos , Carne Roja/normas , Salmonella typhimurium/efectos de los fármacos , Vitis/química
12.
Int J Food Microbiol ; 337: 108936, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33161345

RESUMEN

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.


Asunto(s)
Descontaminación/métodos , Escherichia coli O157/efectos de los fármacos , Escherichia coli O157/efectos de la radiación , Microbiología de Alimentos/métodos , Aceites Volátiles/farmacología , Ondas Ultrasónicas , Recuento de Colonia Microbiana , Lycopersicon esculentum/microbiología
13.
Int J Food Microbiol ; 337: 108938, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33166912

RESUMEN

A packaging system using gaseous chlorine dioxide generating film (CDGF) in a sealed container was developed to extend the shelf life of semi-dry longan pulp (moisture content 38.8 wt%; aw0.8). The antimicrobial properties, formation of chloroxyanion residues and effects of CDGF on the quality of semi-dry longan pulp were investigated. CDGF was triggered by the moisture vapor from semi-dry longan pulp in the sealed container and released gaseous ClO2 into the headspace of the container. The antifungal test showed that CDGF significantly inactivated artificially inoculated molds in semi-dry longan pulp and achieved reductions of over 3 log CFU/g after 28 days storage at room temperature (25 °C). CDGF reduced total aerobic bacterial populations by over 6.4 log CFU/g and maintained these population levels at around 2.0 log CFU/g throughout the 180-day storage period at room temperature. The residual concentrations of chloride, chlorate and perchlorate in longan pulp increased and then decreased during the 180-day storage. Residual chloride levels were maintained at 1.5 mg/g after Day 120 and residual chlorate and perchlorate levels were not detected after Day 120 and Day 180, respectively, in CDGF-treated samples. CDGF treatments reduced total polyphenol content but didn't have any significant impact on the levels of polysaccharides in samples. There were no significant differences between CDGF-treated and control samples in color changes during storage. The content of 5-hydroymethylfurfural (5-HMF) in both samples increased during storage, suggesting that the Maillard reaction occurred. This study demonstrated an effective approach to develop a new antimicrobial packaging system for semi-dry longan pulp.


Asunto(s)
Compuestos de Cloro/farmacología , Microbiología de Alimentos , Almacenamiento de Alimentos/métodos , Óxidos/farmacología , Cloruros/análisis , Recuento de Colonia Microbiana , Desinfectantes/farmacología , Hongos/efectos de los fármacos , Gases/farmacología , Percloratos/análisis , Sapindaceae/microbiología
14.
PLoS One ; 15(12): e0238901, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33338037

RESUMEN

Despite the recent increase in interest in indoor air quality regarding mould, there is no universally accepted standard media for the detection of airborne fungi, nor verification of many commonly used techniques. Commonly used media including malt-extract agar (MEA), Sabouraud dextrose agar (Sab), potato dextrose agar (PDA) with and without antibiotics chloramphenicol & gentamycin (CG) were compared for their suitability in detecting a range of airborne fungi by collecting 150 L outdoor air on a number of different days and seasons via an Anderson 400-hole sampler in suburban Melbourne, Australia. There was relatively little variation in mean numbers of colony forming units (CFU) and types of fungi recovered between MEA, PDA, Sab media groups relative to variation within each group. There was a significant difference between Sab, Dichloran-18% glycerol (DG18) and V8® Original juice agar media, however. Antibiotics reliably prevented the growth of bacteria that typically interfered with the growth and appearance of fungal colonies. There was no significant evidence for a growth enhancing factor from potato, mineral supplements or various vegetable juices. Differing glucose concentrations had modest effects, showing a vague ideal at 2%-4% with peptone. Sanitisation of the aluminium Andersen 400-hole sampler top-plate by flame is possible, but not strictly required nor advisable. The use of SabCG as a standard medium was generally supported.


Asunto(s)
Hongos/crecimiento & desarrollo , Agar/metabolismo , Microbiología del Aire , Contaminación del Aire Interior/análisis , Australia , Recuento de Colonia Microbiana/métodos , Medios de Cultivo/metabolismo , Monitoreo del Ambiente/métodos , Estaciones del Año
15.
J Oleo Sci ; 69(11): 1481-1486, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33132280

RESUMEN

Via utilizing the mixed-ligand method, a novel coordination polymer (CP) containing Cu(II) has been prepared by self-assembly at the ambient temperature, and its chemical formula is {[Cu(BINDI)0.5 (bpe)]·3H2O} n (1, bpe = 1,2-bis(4-pyridyl)ethylene and H4BINDI = N,N'-bis(5-isophthalic acid) naphthalenediimide). For the treatment of the tuberculosis, its biological function was evaluated as well. The CFU assay was performed to determine the bacterial numbers of the Mycobacterium in alveolar macrophages. In addition to this, the ropA gene of the Mycobacterium in alveolar macrophages was also detected through the real time RT-PCR method. Only the oxygen atoms on the metal complex are identified to be able to interact with the probe protein by molecular docking simulation.


Asunto(s)
Cobre/farmacología , Macrófagos Alveolares/microbiología , Mycobacterium tuberculosis/efectos de los fármacos , Polímeros/farmacología , Proteínas Bacterianas/análisis , Proteínas Bacterianas/genética , Recuento de Colonia Microbiana , Cobre/química , Cobre/uso terapéutico , Expresión Génica/efectos de los fármacos , Ligandos , Conformación Molecular , Simulación del Acoplamiento Molecular , Mycobacterium tuberculosis/genética , Oxígeno , Polímeros/química , Polímeros/uso terapéutico , Reacción en Cadena en Tiempo Real de la Polimerasa , Tuberculosis/tratamiento farmacológico , Tuberculosis/microbiología
16.
Sci Rep ; 10(1): 16084, 2020 09 30.
Artículo en Inglés | MEDLINE | ID: mdl-32999342

RESUMEN

Populations of genetically identical bacteria are phenotypically heterogeneous, giving rise to population functionalities that would not be possible in homogeneous populations. For instance, a proportion of non-dividing bacteria could persist through antibiotic challenges and secure population survival. This heterogeneity can be studied in complex environmental or clinical samples by spreading the bacteria on agar plates and monitoring time to growth resumption in order to infer their metabolic state distribution. We present ColTapp, the Colony Time-lapse application for bacterial colony growth quantification. Its intuitive graphical user interface allows users to analyze time-lapse images of agar plates to monitor size, color and morphology of colonies. Additionally, images at isolated timepoints can be used to estimate lag time. Using ColTapp, we analyze a dataset of Staphylococcus aureus time-lapse images including populations with heterogeneous lag time. Colonies on dense plates reach saturation early, leading to overestimation of lag time from isolated images. We show that this bias can be corrected by taking into account the area available to each colony on the plate. We envision that in clinical settings, improved analysis of colony growth dynamics may help treatment decisions oriented towards personalized antibiotic therapies.


Asunto(s)
Recuento de Colonia Microbiana/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Programas Informáticos , Agar , Algoritmos , Carga Bacteriana/métodos , Carga Bacteriana/estadística & datos numéricos , Recuento de Colonia Microbiana/estadística & datos numéricos , Humanos , Procesamiento de Imagen Asistido por Computador/estadística & datos numéricos , Staphylococcus aureus/citología , Staphylococcus aureus/crecimiento & desarrollo , Imagen de Lapso de Tiempo , Interfaz Usuario-Computador
17.
Cochrane Database Syst Rev ; 10: CD013686, 2020 10 12.
Artículo en Inglés | MEDLINE | ID: mdl-33047816

RESUMEN

BACKGROUND: Many dental procedures produce aerosols (droplets, droplet nuclei and splatter) that harbour various pathogenic micro-organisms and may pose a risk for the spread of infections between dentist and patient. The COVID-19 pandemic has led to greater concern about this risk. OBJECTIVES: To assess the effectiveness of methods used during dental treatment procedures to minimize aerosol production and reduce or neutralize contamination in aerosols. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases on 17 September 2020: Cochrane Oral Health's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library, 2020, Issue 8), MEDLINE Ovid (from 1946); Embase Ovid (from 1980); the WHO COVID-19 Global literature on coronavirus disease; the US National Institutes of Health Trials Registry (ClinicalTrials.gov); and the Cochrane COVID-19 Study Register. We placed no restrictions on the language or date of publication. SELECTION CRITERIA: We included randomized controlled trials (RCTs) and controlled clinical trials (CCTs) on aerosol-generating procedures (AGPs) performed by dental healthcare providers that evaluated methods to reduce contaminated aerosols in dental clinics (excluding preprocedural mouthrinses). The primary outcomes were incidence of infection in dental staff or patients, and reduction in volume and level of contaminated aerosols in the operative environment. The secondary outcomes were cost, accessibility and feasibility. DATA COLLECTION AND ANALYSIS: Two review authors screened search results, extracted data from the included studies, assessed the risk of bias in the studies, and judged the certainty of the available evidence. We used mean differences (MDs) and 95% confidence intervals (CIs) as the effect estimate for continuous outcomes, and random-effects meta-analysis to combine data. We assessed heterogeneity. MAIN RESULTS: We included 16 studies with 425 participants aged 5 to 69 years. Eight studies had high risk of bias; eight had unclear risk of bias. No studies measured infection. All studies measured bacterial contamination using the surrogate outcome of colony-forming units (CFU). Two studies measured contamination per volume of air sampled at different distances from the patient's mouth, and 14 studies sampled particles on agar plates at specific distances from the patient's mouth. The results presented below should be interpreted with caution as the evidence is very low certainty due to heterogeneity, risk of bias, small sample sizes and wide confidence intervals. Moreover, we do not know the 'minimal clinically important difference' in CFU. High-volume evacuator Use of a high-volume evacuator (HVE) may reduce bacterial contamination in aerosols less than one foot (~ 30 cm) from a patient's mouth (MD -47.41, 95% CI -92.76 to -2.06; 3 RCTs, 122 participants (two studies had split-mouth design); very high heterogeneity I² = 95%), but not at longer distances (MD -1.00, -2.56 to 0.56; 1 RCT, 80 participants). One split-mouth RCT (six participants) found that HVE may not be more effective than conventional dental suction (saliva ejector or low-volume evacuator) at 40 cm (MD CFU -2.30, 95% CI -5.32 to 0.72) or 150 cm (MD -2.20, 95% CI -14.01 to 9.61). Dental isolation combination system One RCT (50 participants) found that there may be no difference in CFU between a combination system (Isolite) and a saliva ejector (low-volume evacuator) during AGPs (MD -0.31, 95% CI -0.82 to 0.20) or after AGPs (MD -0.35, -0.99 to 0.29). However, an 'n of 1' design study showed that the combination system may reduce CFU compared with rubber dam plus HVE (MD -125.20, 95% CI -174.02 to -76.38) or HVE (MD -109.30, 95% CI -153.01 to -65.59). Rubber dam One split-mouth RCT (10 participants) receiving dental treatment, found that there may be a reduction in CFU with rubber dam at one-metre (MD -16.20, 95% CI -19.36 to -13.04) and two-metre distance (MD -11.70, 95% CI -15.82 to -7.58). One RCT of 47 dental students found use of rubber dam may make no difference in CFU at the forehead (MD 0.98, 95% CI -0.73 to 2.70) and occipital region of the operator (MD 0.77, 95% CI -0.46 to 2.00). One split-mouth RCT (21 participants) found that rubber dam plus HVE may reduce CFU more than cotton roll plus HVE on the patient's chest (MD -251.00, 95% CI -267.95 to -234.05) and dental unit light (MD -12.70, 95% CI -12.85 to -12.55). Air cleaning systems One split-mouth CCT (two participants) used a local stand-alone air cleaning system (ACS), which may reduce aerosol contamination during cavity preparation (MD -66.70 CFU, 95% CI -120.15 to -13.25 per cubic metre) or ultrasonic scaling (MD -32.40, 95% CI - 51.55 to -13.25). Another CCT (50 participants) found that laminar flow in the dental clinic combined with a HEPA filter may reduce contamination approximately 76 cm from the floor (MD -483.56 CFU, 95% CI -550.02 to -417.10 per cubic feet per minute per patient) and 20 cm to 30 cm from the patient's mouth (MD -319.14 CFU, 95% CI - 385.60 to -252.68). Disinfectants ‒ antimicrobial coolants Two RCTs evaluated use of antimicrobial coolants during ultrasonic scaling. Compared with distilled water, coolant containing chlorhexidine (CHX), cinnamon extract coolant or povidone iodine may reduce CFU: CHX (MD -124.00, 95% CI -135.78 to -112.22; 20 participants), povidone iodine (MD -656.45, 95% CI -672.74 to -640.16; 40 participants), cinnamon (MD -644.55, 95% CI -668.70 to -620.40; 40 participants). CHX coolant may reduce CFU more than povidone iodine (MD -59.30, 95% CI -64.16 to -54.44; 20 participants), but not more than cinnamon extract (MD -11.90, 95% CI -35.88 to 12.08; 40 participants). AUTHORS' CONCLUSIONS: We found no studies that evaluated disease transmission via aerosols in a dental setting; and no evidence about viral contamination in aerosols. All of the included studies measured bacterial contamination using colony-forming units. There appeared to be some benefit from the interventions evaluated but the available evidence is very low certainty so we are unable to draw reliable conclusions. We did not find any studies on methods such as ventilation, ionization, ozonisation, UV light and fogging. Studies are needed that measure contamination in aerosols, size distribution of aerosols and infection transmission risk for respiratory diseases such as COVID-19 in dental patients and staff.


Asunto(s)
Microbiología del Aire , Infecciones Bacterianas/prevención & control , Control de Infección Dental/métodos , Enfermedades Profesionales/prevención & control , Virosis/prevención & control , Adolescente , Adulto , Aerosoles , Anciano , Filtros de Aire , Niño , Preescolar , Recuento de Colonia Microbiana/métodos , Odontología , Desinfectantes , Humanos , Control de Infección Dental/economía , Control de Infección Dental/instrumentación , Persona de Mediana Edad , Ensayos Clínicos Controlados Aleatorios como Asunto/estadística & datos numéricos , Dique de Goma , Succión , Adulto Joven
18.
Int J Food Microbiol ; 335: 108887, 2020 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-33002710

RESUMEN

Disinfection of fruits is one of the most important steps since they are going to be eaten fresh-or minimally-processed. This step affects quality, safety, and shelf-life of the product. Despite being a common sanitizer in the fruit industry, chlorine may react with organic matter leading to the formation of toxic by-products. Alternative sustainable disinfection strategies to chlorine are under study to minimize environmental and human health impact. Water-assisted UV-C light (WUV-C) is proposed here as an alternative sanitizing method for strawberries. In this study, strawberries were washed for 1 or 5 min in a tank with 2 or 4 lamps on, each emitting UV-C light at 17.2 W/cm2, or in a chlorine solution (200 ppm, pH 6.5). Moreover, trials with 4 lamps on, together with a washing solution consisting on peracetic acid at 40 or 80 ppm, were carried out. Overall, quality and nutritional parameters of strawberries after treatments were maintained. Changes in color were not noticeable and fruits did not lose firmness. No major changes were observed in antioxidant activity, organic acid, anthocyanin, vitamin C, and total phenolic content. Yeasts and molds were not affected by the WUV-C treatment, and 5 min were needed to significantly reduce total aerobic mesophylls population. However, reductions of artificially inoculated Listeria innocua and Salmonella Typhimurium after WUV-C treatments were comparable to those obtained with chlorine-wash, which were 3.0 log CFU / g. Moreover, WUV-C light was effective to minimize microorganisms remaining in washing water, avoiding cross-contamination and thus, allowing water recirculation. This effect was improved when combining the action of UV-C light with peracetic acid, showing the suitability of this combined treatment, understood as an alternative to chlorine sanitation, for sanitizing strawberries and keeping the populations of pathogenic bacteria in washing water lower than 0.6 ±â€¯0.1 log CFU / mL.


Asunto(s)
Desinfectantes/farmacología , Desinfección/métodos , Fragaria/microbiología , Ácido Peracético/farmacología , Rayos Ultravioleta , Bacterias/efectos de los fármacos , Bacterias/efectos de la radiación , Cloro/farmacología , Recuento de Colonia Microbiana , Microbiología de Alimentos , Frutas/microbiología
19.
Int J Food Microbiol ; 335: 108888, 2020 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-33027736

RESUMEN

During the last decades, thermophilic spore counts became a very important quality parameter for manufacturers with regard to powdered dairy products. Low-spore count powders are highly demanded but challenging to produce when high production volume and long process times are intended. In this study a detailed monitoring of microbial levels in three skim milk powder plants was conducted. Anoxybacillus flavithermus was found to be primarily responsible for increased spore levels with increasing spore numbers being detected after 6-8 h already during initial processing steps. Simultaneously, the species composition shifted from a diverse bulk tank milk microbiota where different Bacillus species represented around 90% of the thermophilic bacteria to a dominance of A. flavithermus in the end product. The analysis of A. flavithermus isolates from different powder batches with RAPD PCR revealed recurring patterns in each of the eight German manufacturers sampled over several months. The high relatedness of isolates exhibiting identical RAPD patterns was exemplified by cgMLST based on whole genome sequences. We assume that A. flavithermus strains persisted in production plants and were not eliminated by cleaning. It is concluded that such persisting strains recurrently recontaminated subsequent powder productions. The data highlight that a targeted optimization of cleaning and disinfection procedures is the most promising measure to effectively reduce thermophilic spore counts in German dairy powders.


Asunto(s)
Productos Lácteos/microbiología , Bacterias Formadoras de Endosporas/aislamiento & purificación , Manipulación de Alimentos , Esporas Bacterianas/aislamiento & purificación , Animales , Recuento de Colonia Microbiana , Bacterias Formadoras de Endosporas/clasificación , Bacterias Formadoras de Endosporas/genética , Microbiología de Alimentos , Genoma Bacteriano/genética , Alemania , Leche/microbiología , Esporas Bacterianas/clasificación , Esporas Bacterianas/genética
20.
Int J Food Microbiol ; 335: 108836, 2020 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-33065380

RESUMEN

Aspergillus flavus is the predominant species that produce aflatoxins in stored peanuts under favourable conditions. This study aimed to describe the growth and aflatoxin production by two A. flavus strains isolated from imported raw peanuts and to model the effects of temperature and aw on their colony growth rate as a function of temperature and aw in Peanut Meal Extract Agar (PMEA). A full factorial design with seven aw levels (0.85-0.98 aw) and five temperature levels (20-40 °C) was used to investigate the growth and aflatoxin production. Colony diameter was measured daily for 28 days while AFB1 and total aflatoxin were determined on day 3, 7, 14, and 21. The maximum colony growth rate, µmax (mm/day) was estimated by using the primary model of Baranyi, and the µmax was then fitted to the secondary model; second-order polynomial and linear Arrhenius-Davey to describe the colony growth rate as a function of temperature and aw. The results indicated that both strains failed to grow at temperature of 20 °C with aw <0.94 and aw of 0.85 for all temperatures except 30 °C. The highest growth rate was observed at 30 °C, with 0.98 aw for both strains. The analysis of variance showed a significant effect of strain, temperature, and aw on the fungal growth and aflatoxin production (p < 0.05). Furthermore, both secondary models were in good agreement with the observed µmax. However, the polynomial model was found to be a better predictor of the experimental data. A similar pattern was observed in aflatoxin production but in a narrower range of temperature (25-35 °C) and aw (0.92-0.98 aw). The highest production of aflatoxins was observed on day 21 at 30 °C with the aw level of 0.98 for both strains. Overall, the current findings may help in improving the mycotoxin management and intervention strategies in peanuts, especially during storage.


Asunto(s)
Aflatoxinas/biosíntesis , Arachis/microbiología , Aspergillus flavus/crecimiento & desarrollo , Temperatura , Aspergillus flavus/metabolismo , Recuento de Colonia Microbiana , Microbiología de Alimentos , Modelos Biológicos , Extractos Vegetales , Agua
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