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1.
Anal Bioanal Chem ; 412(3): 611-620, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31900539

RESUMEN

Infections caused by foodborne microorganisms are a great threat to the global environment and public healthcare today. Thus, rapid, portable and sensitive assays that can realize the identification of foodborne bacteria are highly desired. In this study, a smart fluorescent and colorimetric dual-readout sensing system has been established for simple and rapid E. coli determination by utilizing the Cu2+-triggered oxidation of o-phenylenediamine (OPD). Initially, Cu2+ can oxidize OPD to OPDox, resulting in an orange-yellow fluorescence and visible pale-yellow color. However, E. coli can effectively reduce Cu2+ into Cu+, inhibiting the Cu2+-triggered oxidation of OPD to OPDox. Consequently, the introduction of E. coli can turn off both the fluorescence and the UV-vis absorbance signals of the OPD-Cu2+ system, illustrating an original mechanism for fluorescent and colorimetric dual-channel detection of E. coli. Moreover, a filter paper-based visual sensor was built and coupled with OPD-Cu2+ solution under the assistance of a UV lamp. The as-prepared sensor can detect E. coli quantitatively with the help of a typical smartphone color-scanning application (APP). Thus, this study offers a valid dual-mode assay for sensitive and on-site visible detection of E. coli, guaranteeing the reliability of the results and is more attractive for practical use. Graphical Abstract Schematic illustration of the smartphone-integrated sensing system for fluorescent and colorimetric dual-channel detection of E. coli based on the Cu2+-OPD system.


Asunto(s)
Bacterias/aislamiento & purificación , Colorimetría/métodos , Colorantes Fluorescentes/química , Microbiología de Alimentos , Papel , Teléfono Inteligente , Espectrometría de Fluorescencia/métodos , Integración de Sistemas , Bacterias/patogenicidad , Técnicas Biosensibles , Reproducibilidad de los Resultados , Espectrofotometría Ultravioleta/métodos
3.
J Agric Food Chem ; 68(1): 301-314, 2020 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-31820631

RESUMEN

Xylooligosaccharides (XOS) from woody biomass were evaluated as a substrate for secondary lactic acid bacteria (LAB) fermentation in sour beer production. XOS were extracted from birch (Betula pubescens) and added to beer to promote the growth of Lactobacillus brevis BSO 464. Growth, pH, XOS degradation, and metabolic products were monitored throughout fermentations, and the final beer was evaluated sensorically. XOS were utilized, metabolic compounds were produced (1800 mg/L lactic acid), and pH was reduced from 4.1 to 3.6. Secondary fermentation changed sensory properties significantly, and the resulting sour beer was assessed as similar to a commercial reference in multiple attributes, including acidic taste. Overall, secondary LAB fermentation induced by wood-derived XOS provided a new approach to successfully produce sour beer with reduced fermentation time (from 1-3 years to 4 weeks). The presented results demonstrate how hemicellulosic biomass can be valorized for beverage production and to obtain sour beer with improved process control.


Asunto(s)
Cerveza/análisis , Microbiología de Alimentos/métodos , Glucuronatos/metabolismo , Lactobacillales/metabolismo , Oligosacáridos/metabolismo , Extractos Vegetales/metabolismo , Madera/química , Cerveza/microbiología , Betula/química , Betula/metabolismo , Betula/microbiología , Fermentación , Humanos , Concentración de Iones de Hidrógeno , Lactobacillales/crecimiento & desarrollo , Gusto , Madera/metabolismo , Madera/microbiología
4.
J Sci Food Agric ; 100(3): 1012-1021, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31646636

RESUMEN

BACKGROUND: Wines are produced via the alcoholic fermentation of suitable substrates, usually sugar (sugar cane, grapes) and carbohydrates (wheat, grain). However, conventional alcoholic fermentation is limited by the inhibition of yeast by ethanol produced, usually at approximately 13-14%. Aside from that, soursop fruit is a very nutritious fruit, although it is highly perishable, and thus produces a lot of wastage. Therefore, the present study aimed to produce fermented soursop juice (soursop wine), using combination of two starter cultures, namely mushroom (Pleurotus pulmonarius) and yeast (Saccharomyces cerevisiae), as well as to determine the effects of fermentation on the physicochemical and antioxidant activities of fermented soursop juice. Optimisation of four factors (pH, temperature, time and culture ratio) using response surface methodology were performed to maximise ethanol production. RESULTS: The optimised values for alcoholic fermentation were pH 4.99, 28.29 °C, 131 h and a 0.42 culture ratio (42:58, P. pulmonarius mycelia:S. cerevisiae) with a predicted ethanol concentration of 22.25%. Through a verification test, soursop wine with 22.29 ± 0.52% ethanol was produced. The antioxidant activities (1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power) showed a significant (P < 0.05) increase from the soursop juice to soursop wine. CONCLUSION: The alternative fermentation technique using yeast and mushroom has successfully been optimised, with an increased ethanol production in soursop wine and higher antioxidant activities. Ultimately, this finding has high potential for application in the brewing industry to enhance the fermentation process, as well as in the development of an innovative niche product, reducing wastage by converting the highly-perishable fruit into wine with a more stable and longer shelf-life. © 2019 Society of Chemical Industry.


Asunto(s)
Annona/microbiología , Microbiología de Alimentos/métodos , Pleurotus/metabolismo , Saccharomyces cerevisiae/metabolismo , Annona/metabolismo , Antioxidantes/análisis , Antioxidantes/metabolismo , Etanol/análisis , Etanol/metabolismo , Fermentación , Vino/análisis
5.
Plant Dis ; 104(1): 105-115, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31660800

RESUMEN

Fungi in the Botryosphaeriaceae family cause dieback, fruit rots, and stem cankers in many tropical fruit trees. To identify which species of Botryosphaeriaceae were present in tropical fruit in Puerto Rico and the symptoms they cause in rambutan and longan, a disease survey was conducted throughout the island from 2008 to 2016. Diseased organs of rambutan, longan, mango, and tangerine were collected and 39 isolates belonging to the Botryosphaeriaceae family were isolated and identified. Phylogenetic analysis of three nuclear genes identified nine species: six Lasiodiplodia spp. and three Neofusicoccum spp. All 39 isolates were inoculated on healthy 1-year-old rambutan and longan seedlings to confirm their pathogenicity. Dieback on both rambutan and longan was observed at 14 days after inoculation (DAI). Fourteen isolates from seven Botryosphaeriaceae species (Lasiodiplodia brasiliensis, L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae, Neofusicoccum batangarum, and N. parvum) caused dieback in rambutan. Five of these pathogenic isolates were collected from rambutan, four from longan, two from mango, and three from tangerine. Ten isolates of four Lasiodiplodia spp. caused dieback in longan: L. hormozganensis, L. iraniensis, L. pseudotheobromae and L. theobromae,. Of these, three were collected from rambutan, three from longan, one from mango, and three from tangerine. Abundant development of pycnidia on branches, called corky bark, were observed on both rambutan and longan 60 DAI. Cross-inoculations showed that pathogenicity is wide in spectrum, indicating that different planting alternatives should be considered for better crop management.


Asunto(s)
Ascomicetos , Microbiología de Alimentos , Frutas , Enfermedades de las Plantas , Ascomicetos/clasificación , Ascomicetos/genética , ADN de Hongos/genética , Frutas/microbiología , Genes Fúngicos/genética , Filogenia , Corteza de la Planta/microbiología , Puerto Rico , Clima Tropical
6.
J Sci Food Agric ; 100(3): 926-935, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31523827

RESUMEN

BACKGROUND: The effects were studied of different inoculation strategies for selected starters -yeasts and lactic acid bacteria (LAB) - used for the fermentation process of two Greek olive cultivars, Conservolea and Kalamàta. The LAB strains applied were Leuconostoc mesenteroides K T5-1 and L. plantarum A 135-5; the selected yeast strains were S. cerevisiae KI 30-16 and Debaryomyces hansenii A 15-44 for Kalamàta and Conservolea olives, respectively. RESULTS: Table olive fermentation processes were monitored by performing microbiological analyses, and by monitoring changes in pH, titratable acidity and salinity, sugar consumption, and the evolution of volatile compounds. Structural modifications occurring in phenolic compounds of brine were investigated during the fermentation using liquid chromatography / diode array detection / electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MSn ) and quantified by high-performance liquid chromatography (HPLC) using a diode array detector. Phenolic compounds in processed Kalamàta olive brines consisted of phenolic acids, verbascoside, caffeoyl-6-secologanoside, comselogoside, and the dialdehydic form of decarboxymethylelenolic acid linked to hydroxytyrosol, whereas oleoside and oleoside 11-methyl ester were identified only in Conservolea olive brines. CONCLUSION: Volatile profile and sensory evaluation revealed that the 'MIX' (co-inoculum of yeast and LAB strain) inoculation strategy led to the most aromatic and acceptable Kalamàta olives. For the Conservolea table olives, the 'YL' treatment gave the most aromatic and the overall most acceptable product. © 2019 Society of Chemical Industry.


Asunto(s)
Debaromyces/metabolismo , Microbiología de Alimentos/métodos , Lactobacillales/metabolismo , Olea/química , Olea/microbiología , Fenol/metabolismo , Saccharomyces cerevisiae/metabolismo , Fermentación , Frutas/química , Frutas/microbiología , Humanos , Fenol/análisis , Sales (Química)/análisis , Sales (Química)/metabolismo , Gusto
7.
Int J Food Microbiol ; 312: 108358, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31655356

RESUMEN

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


Asunto(s)
Contaminación de Alimentos/análisis , Microbiología de Alimentos , Listeria monocytogenes/aislamiento & purificación , Productos de la Carne/microbiología , Aves de Corral/microbiología , Animales , Bovinos , China , Humanos , Listeriosis/epidemiología , Prevalencia , Ovinos , Porcinos
8.
Int J Food Microbiol ; 312: 108387, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31669763

RESUMEN

Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by <0.6 log CFU/fruit on both the smooth surface and the stem scar area, and aerosolized hydrogen peroxide alone reduced the populations by up to 2.1 log CFU/fruit on the smooth surface and 0.8 log CFU/fruit on stem scar area. However, the combination treatments reduced the populations by up to 5.2 log CFU/fruit on smooth surface and 4.2 log CFU/fruit on the stem scar. Overall, our results demonstrate that gaseous ozone and aerosolized hydrogen peroxide have synergistic effects on the reduction of Salmonella populations on tomatoes.


Asunto(s)
Enfermedades Transmitidas por los Alimentos/prevención & control , Peróxido de Hidrógeno/farmacología , Lycopersicon esculentum/microbiología , Ozono/farmacología , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/crecimiento & desarrollo , Recuento de Colonia Microbiana , Microbiología de Alimentos/métodos , Frutas/microbiología , Oxidación-Reducción
9.
Int J Food Microbiol ; 312: 108374, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31669765

RESUMEN

Salmonella enterica outbreaks in sprouts originate from contaminated seeds; conventional prevention technologies have been reported from many research institutes. In this study, we applied a biological control approach to inhibit S. enterica growth using the seed-dwelling non-antagonistic bacteria. We isolated non-antibacterial seed-dwelling bacteria from vegetable sprouts. A total of 206 bacteria exhibiting non-antibacterial activity against S. enterica were subjected to alfalfa sprout development tests. Eight isolates exhibiting no deleterious effect on the growth of alfalfa sprouts were tested for S. enterica growth inhibition on alfalfa seeds and sprouts, and an isolate EUS78 was finally selected for further investigation. Based on 16S rRNA, gyrB, and rpoB gene sequence analyses, strain EUS78 was identified as Erwinia persicina. In population competition, the S. enterica population increased by >3 log CFU/g after 6 days of alfalfa sprout growth, whereas S. enterica growth was significantly inhibited by treatment with EUS78 (P < .05). This effect of S. enterica growth inhibition by EUS78 was sustained until the end of the alfalfa sprout harvest. Overall, bacterial strain EUS78 significantly reduced S. enterica growth on alfalfa sprouts in a manner consistent with competitive exclusion. These findings led us to monitor EUS78 behavior on seeds during early sprout development using fluorescence and scanning electron microscopy. Strain EUS78 initially colonized alfalfa sprout seed coat edges, cotyledons, and finally root surfaces during early sprout germination. As alfalfa sprouts grew, EUS78 bacterial cells established colonies on newly emerged plant tissues such as root tips. The results of this study suggest that strain EUS78 has potential as a biological control agent to inhibit S. enterica contamination in the sprout food industry.


Asunto(s)
Antibiosis/fisiología , Agentes de Control Biológico , Erwinia/fisiología , Medicago sativa/microbiología , Salmonella enterica/crecimiento & desarrollo , Semillas/microbiología , Girasa de ADN/genética , ARN Polimerasas Dirigidas por ADN/genética , Erwinia/genética , Microbiología de Alimentos , Industria de Procesamiento de Alimentos , Germinación/fisiología , Medicago sativa/química , ARN Ribosómico 16S/genética , Verduras/microbiología
10.
Crit Rev Food Sci Nutr ; 60(2): 225-243, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-30421977

RESUMEN

Cross-contamination can be broadly defined as the transfer, direct or indirect, of microorganisms from a contaminated product to a non-contaminated product. Events that may result in cross-contamination include inadequate hygiene practices, contaminated equipment surfaces, contamination via food handling personnel, further product processing, or storage abuse All of these niches require consistent environmental surveillance systems to monitor microbial harborage sites to prevent foodborne illnesses via cross-contamination. Environmental surveillance is achieved through routine surface sampling of the food contact surfaces and surrounding areas. To better understand cross-contamination, the role of environmental surface transmission during outbreaks due to the presence and persistence of pathogenic microorganisms on various food contact surfaces must be investigated. However, studies on environmental sampling techniques are rarely performed in an actual food processing environment but rather under controlled variables within a laboratory-setting. Moreover, results and conclusions of studies differ because of the considerable variability across surface sampling tools due to individual operator dependency, low recovery rates, and low reproducibility. Information is also often lacking on environmental sampling tools used within a processing facility, the characterization of these tools, and the optimization of recovery of microorganisms for surface sampling. Thus, this review aims to: (1) discuss and compare factors impacting the recovery of microorganisms and the standardization of surface sampling methods for optimal recovery of microorganisms and (2) examine how research strategies could focus more towards the development of standard methodologies for surface sampling.


Asunto(s)
Monitoreo del Ambiente , Enfermedades Transmitidas por los Alimentos , Contaminación de Equipos , Contaminación de Alimentos , Manipulación de Alimentos , Microbiología de Alimentos , Humanos , Reproducibilidad de los Resultados
11.
Crit Rev Food Sci Nutr ; 60(2): 310-321, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-30431327

RESUMEN

Bakery products, as an important part of a healthy diet, are characterized by their limited shelf-life. Microbiological spoilage of these products not only affects the quality characteristics and result in the economic loss but also threatens consumer's health. Incorporation of chemical preservatives, as one of the most conventional preserving techniques, lost its popularity due to the increasing consumer's health awareness. Therefore, the bakery industry is seeking alternatives to harmful antimicrobial agents that can be accepted by health-conscious customers. In this regard, essential oils have been previously used as either a part of product ingredient or a part of the packaging system. Therefore, the antimicrobial aspect of essential oils and their ability in delaying the microbiological spoilage of bakery products have been reviewed. Several types of essential oils, including thyme, cinnamon, oregano, and lemongrass, can inhibit the growth of harmful microorganisms in bakery products, resulting in a product with extended shelf-life and enhanced safety. Research revealed that several bioactive compounds are involved in the antimicrobial activity of essential oils. However, some limitations, such as the possible negative effects of essential oils on sensory parameters, may limit their applications, especially in high concentrations. In this case, they can be used in combination with other preservation techniques such as using appropriate packaging materials. Further research regarding the commercial production of the bakery products formulated with essential oils is required in this area.


Asunto(s)
Conservación de Alimentos , Aceites Volátiles , Origanum , Antiinfecciosos , Microbiología de Alimentos , Conservantes de Alimentos , Thymus (Planta)
12.
J Appl Microbiol ; 128(1): 301-309, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31541508

RESUMEN

AIMS: The aim of this study was to evaluate the microbiological quality of commercially prepared ready-to-eat (RTE) sushi by enumerating aerobic mesophilic bacteria (AMB) and thermotolerant coliforms (TC) and detecting Escherichia coli and Salmonella ssp. An isolate was identified as E. coli O157:H7 which was evaluated for its virulence and antimicrobial resistance profiling as well as its ability to form biofilms on stainless steel. METHODS AND RESULTS: There were four sampling events in seven establishments, totalling 28 pools of sushi samples. Mean AMB counts ranged between 5·2 and 7·7 log CFU per gram. The enumeration of TC varied between 2·1 and 2·7 log MPN per gram. Salmonella ssp. were not detected, and one sample was positive for E. coli and was identified as E. coli O157:H7. To the best of our knowledge, this is the first report of E. coli O157:H7 in sushi samples in the world literature. This isolate presented virulence genes stx1, stx2, eae and hlyA. It was also susceptible to 14 antimicrobials tested and had the ability to form biofilms on stainless steel. CONCLUSIONS: There is a need to improve the good hygiene practices adopted in establishments selling sushi in the city of Pelotas, Brazil. In addition, the isolated E. coli O157:H7 carries a range of important virulence genes being a potential risk to consumer health, as sushi is a RTE food. This isolate also presents biofilm formation ability, therefore, may trigger a constant source of contamination in the production line of this food. SIGNIFICANCE AND IMPACT OF THE STUDY: The increase in the consumption of sushi worldwide attracts attention regarding the microbiological point of view, since it is a ready-to-eat food. To our knowledge, this was the first time that E. coli O157:H7 was identified in sushi samples.


Asunto(s)
Escherichia coli O157/aislamiento & purificación , Microbiología de Alimentos , Alimentos Marinos/microbiología , Animales , Antibacterianos/farmacología , Biopelículas/crecimiento & desarrollo , Brasil , Recuento de Colonia Microbiana , Escherichia coli O157/efectos de los fármacos , Escherichia coli O157/genética , Escherichia coli O157/crecimiento & desarrollo , Pruebas de Sensibilidad Microbiana , Acero Inoxidable , Termotolerancia , Virulencia/genética
13.
Lett Appl Microbiol ; 70(1): 13-20, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31627244

RESUMEN

This study investigated the potential causative agents for vacuum-packaged pork that had shown gross package extension during a routine storage life study in a Canadian pork plant using both conventional and culture-independent methods. The spoilage-associated bacteria in purge samples from two packages were enumerated using selective media and profiled using 16S rDNA amplicon analysis. The presence of Clostridium estertheticum was detected using species-specific real-time PCR. An enrichment procedure was used to isolate C. estertheticum from one of the purge samples. The average population density in the two purge samples of total aerobes, lactic acid bacteria (LAB), coliforms and Brochothrix thermosphacta was 9·4, 9·1, 6·0 and 4·6 log CFU per ml respectively, as determined by plating. The estimated numbers of C. estertheticum were >7 log cells per ml. Clostridium estertheticum was recovered although the enrichment condition used for isolation favoured the growth of LAB more than that of Clostridium spp. Based on 16S rDNA amplicon analysis, the microbiota in the two purge samples had 64·7 and 20·7% of Clostridium spp., and 32·5 and 70·1% of LAB respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Blown pack spoilage of vacuum-packaged meat may lead to severe economic losses and is often associated with beef, venison and lamb. This study is the first to report vacuum-packaged chilled pork can also be subject to blown pack spoilage, and data support the conclusion that the causative agent is likely Clostridium estertheticum. The lysozyme-digestion step greatly improved the isolation efficiency for C. estertheticum, a spore-forming anaerobic organism that has been proven to be difficult to recover. This method can be used for isolating spore-forming organisms from food samples.


Asunto(s)
Clostridium/aislamiento & purificación , Carne Roja/microbiología , Animales , Canadá , Bovinos , Clostridium/genética , Contaminación de Alimentos/análisis , Microbiología de Alimentos , Embalaje de Alimentos/instrumentación , Embalaje de Alimentos/métodos , Carne Roja/análisis , Porcinos , Vacio
14.
Lett Appl Microbiol ; 70(1): 48-54, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31642537

RESUMEN

This study aims to describe the native microbiota of fermented spelt, taking into consideration both lactic acid bacteria (LAB) and yeasts, for which little data are available. Five samples of commercial spelt flour were subjected to spontaneous fermentation to obtain a type I sourdough. A total of 186 LAB and 174 yeast isolates were selected at different refreshment steps and subjected to further analyses. Within LAB, coccal isolates constituted 78·5% of the total LAB, with the dominance of Pediococcus pentosaceus. Although documented before as a component, this is the first report of a spelt sourdough fermentation dominated by this homofermentative LAB, characterized by a high acidification rate, ability to utilize a wide range of carbon sources and to grow in high osmolarity conditions. Yeast communities resulted in four dominant species, Saccharomyces cerevisiae, Wickerhamomyces anomalus, Pichia fermentans and Clavispora lusitaniae. This study highlights for the first time the biodiversity and dynamics of yeast communities involved in sourdough fermentation of spelt. Compared to commercial baker's yeast, autochthonous W. anomalus, P. fermentans and S. cerevisiae isolates show a good performance, and their use could be an advantage for their acquired adaptation to the environment, providing stability to the fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Nowadays, there is a renewed interest in products based on spelt. This 'ancient grain' is a highly nutritional grain; however, its use is limited to bread-making processes, which are not standardized. The low baking and sensory quality of spelt can be overcome through fermentation processes. However, the autochthonous microbiota of spelt sourdough is poorly known. This study highlights the dynamics of microbial communities involved in sourdough fermentation of spelt and provides the basis for the selection of autochthonous cultures, with the aim of improving the nutritional potential of spelt and its rheology and bread-making properties.


Asunto(s)
Pan/microbiología , Lactobacillales/metabolismo , Consorcios Microbianos , Triticum/microbiología , Levaduras/metabolismo , Biodiversidad , Pan/análisis , Fermentación , Harina/microbiología , Microbiología de Alimentos , Lactobacillales/clasificación , Lactobacillales/genética , Lactobacillales/aislamiento & purificación , Triticum/metabolismo , Levaduras/clasificación , Levaduras/genética , Levaduras/aislamiento & purificación
15.
Toxicol Lett ; 318: 74-85, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31654802

RESUMEN

Metabolic flexibility defines the capacity of cells to respond to changes in nutrient status. Mitochondria are important mediators of metabolic flexibility and dysfunction is associated with metabolic inflexibility and pathology. Foodborne toxins are often overlooked as potential factors contributing to metabolic toxicity. Fusaric acid (FA), a neglected mycotoxin, is known to disrupt mitochondrial function. The aim of this study was to investigate the molecular mechanisms underlying a metabolic switch in response to FA. This study investigated the effects of FA on energy homeostasis in cultured human liver (HepG2) cells. HepG2 cells poised to undergo oxidative and glycolytic metabolism were exposed to a range of FA concentrations (4, 63 and 250 µg/mL) for 6 h. We determined mitochondrial toxicity, acetyl CoA levels and cell viability using luminometric, fluorometric and spectrophotometric methods. Expression of metabolic proteins (PDK1, PKM2, phosphorylated-PDH E1α and HIF-1α) and mRNAs (HIF-1α, PKM2, LDHa and PDK1) were determined using western blot and qPCR respectively. Our data connects a constitutive expression of HIF-1α in response to FA, to the inhibition of pyruvate decarboxylation through up-regulation of PDK-1 and phosphorylation of Pyruvate Dehydrogenase E1α subunit. Moreover, we highlight the potential of FA to induce a glucose "addiction" and phenotype reminiscent of the Warburg effect. The findings provide novel insights into the impact of this neglected foodborne mycotoxin in the dysregulation of energy metabolism.


Asunto(s)
Plasticidad de la Célula/efectos de los fármacos , Microbiología de Alimentos , Ácido Fusárico/toxicidad , Glucólisis/efectos de los fármacos , Hepatocitos/efectos de los fármacos , Mitocondrias Hepáticas/efectos de los fármacos , Células Hep G2 , Hepatocitos/metabolismo , Hepatocitos/patología , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Mitocondrias Hepáticas/metabolismo , Mitocondrias Hepáticas/patología , Fenotipo , Fosforilación , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Piruvato Deshidrogenasa (Lipoamida)/metabolismo
16.
Food Microbiol ; 85: 103279, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500702

RESUMEN

Cereulide, a potent toxin produced by Bacillus cereus, is a small, highly heat- and acid-resistant depsipeptide toxin, which confronts food industry with several challenges. Due to the ubiquitous presence of B. cereus in the environment, this opportunistic pathogen can enter food production and processing at almost any stage. Although the bacteria itself might be removed during food processing, the cereulide toxin will most likely not be destroyed or inactivated by these processes. Because of the high toxicity of cereulide and the high incidence rates often observed in connection with foodborne outbreaks, the understanding of the mechanisms of toxin production as well as accurate data on contamination sources and factors promoting toxin formation are urgently needed to prevent contamination and toxin production in food production processes. Over the last decade, considerable progress had been made on the understanding of cereulide toxin biosynthesis in emetic B. cereus, but an overview of current knowledge on this toxin with regards to food industry perspective is lacking. Thus, we aim in this work to summarize data available on extrinsic parameters acting on cereulide toxin synthesis in emetic B. cereus and to discuss the food industry specific challenges related to this toxin. Furthermore, we emphasize how identification of the cardinals in food production processes can lead to novel effective strategies for prevention of toxin formation in the food processing chain and could contribute to the improvement of existing HACCP studies.


Asunto(s)
Bacillus cereus/metabolismo , Depsipéptidos/biosíntesis , Contaminación de Alimentos/análisis , Microbiología de Alimentos , Enfermedades Transmitidas por los Alimentos/prevención & control , Toxinas Bacterianas/biosíntesis , Brotes de Enfermedades/prevención & control , Contaminación de Alimentos/prevención & control , Manipulación de Alimentos , Industria de Alimentos/métodos , Industria de Alimentos/normas
17.
Food Microbiol ; 85: 103306, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500703

RESUMEN

Spray dried egg white powder (EWP) is traditionally processed by hot room treatment for a prolonged period of time (67 °C for 15 days) to enhance its functionality (foaming and gelling) and to improve microbial safety of EWP. Our prior research demonstrated that radio-frequency (RF) assisted thermal processing can considerably reduce the processing time, without compromising the functional properties of EWP. In this study, continuous RF processing was evaluated for pasteurization of EWP. EWP samples were inoculated with a 5-strain Salmonella cocktail or Enterococcus faecium NRRL B-2354 for the microbial challenge studies. To evaluate the inoculation method, stability and homogeneity tests were conducted for both Salmonella and E. faecium in EWP. Continuous RF heating of EWP was conducted in a 6-kW, 27.12 MHz pilot-scale parallel-plate RF heating system. RF-assisted thermal processing of EWP at 80 °C for 2 h provided >6.69 log reduction for Salmonella. E. faecium was found to be a suitable surrogate for Salmonella due to its higher resistance and similar inactivation kinetics during RF heating of EWP. The validated RF-assisted thermal process can be scaled up for use in the egg industry.


Asunto(s)
Clara de Huevo/microbiología , Microbiología de Alimentos/métodos , Análisis de Peligros y Puntos de Control Críticos/métodos , Calor , Pasteurización/métodos , Ondas de Radio , Recuento de Colonia Microbiana , Polvos/análisis , Salmonella
18.
Food Microbiol ; 85: 103280, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500706

RESUMEN

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


Asunto(s)
Monitoreo Epidemiológico , Microbiología de Alimentos , Enfermedades Transmitidas por los Alimentos/epidemiología , Listeria monocytogenes/genética , Listeriosis/epidemiología , Chile/epidemiología , Recuento de Colonia Microbiana , ADN Bacteriano/genética , Brotes de Enfermedades , Enfermedades Transmitidas por los Alimentos/microbiología , Gastroenteritis/epidemiología , Gastroenteritis/microbiología , Variación Genética , Humanos , Listeria monocytogenes/patogenicidad , Productos de la Carne/microbiología , Epidemiología Molecular , Salud Pública , Serogrupo , Serotipificación , Factores de Virulencia/genética
19.
Food Microbiol ; 85: 103286, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500709

RESUMEN

Hispanic style soft non-fermented cheeses, such as queso fresco (QF) have been linked to outbreaks and recalls. Salmonella is one of the main causes of these incidents. Due to lack of ripening or post-processing antimicrobial treatments, incorporating GRAS antimicrobials to production process may be a suitable approach to minimize microbial risk in QF. The aim of this study was to evaluate the efficiency of nisin (N), caprylic acid (CA) and trans-cinnamaldehyde (CN) as single or combined treatments to reduce Salmonella populations in QF during storage. Batches of QF were inoculated after curding with approx. 4 Log CFU/g of 5-strain cocktails of Salmonella and stored at 8 °C for 20 days. The final Salmonella counts in control samples ranged from 6.96 to 7.14 Log CFU/g. Application of CN at 0.6 g/kg inhibited Salmonella growth during storage, resulting in at least 3 Log CFU/g difference with the untreated controls (p < 0.05). Addition of N (0.5 g/kg) and CA (0.4 g/kg) with CN (0.3 and 0.6 g/kg) further enhanced the antimicrobial activity resulting in complete suppression of growth and even caused a 1 Log CFU/g reduction by the end of the experimental period compared to initial counts. Samples treated with the combined treatment (N, CA, CN) were evaluated in a consumer panel (n = 112). Participants preferred the control and commercial QF to the treated samples. However, treated samples with 0.3 g/kg CN were still within the acceptable range of neutral to like slightly. Results obtained, revealed that combined treatment of N, CA and CN can provide a solution to reduce the count of Salmonella in QF, whether in process or during storage.


Asunto(s)
Antibacterianos/farmacología , Queso/microbiología , Microbiología de Alimentos/métodos , Viabilidad Microbiana/efectos de los fármacos , Salmonella/efectos de los fármacos , Caprilatos/farmacología , Recuento de Colonia Microbiana , Manipulación de Alimentos , Conservación de Alimentos , Nisina/farmacología
20.
Food Microbiol ; 85: 103282, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31500713

RESUMEN

Two biopreservation approaches for fresh lettuce, rocket salad, parsley and spinach were studied. The potential of Pediococcus pentosaceus DT016, as a protective culture, to suppress Listeria monocytogenes in vegetables during storage was evaluated. The pathogen numbers in the vegetables inoculated with P. pentosaceus DT016 were significantly (p < 0.01) lower throughout the storage period and, at the last storage day, a minimum difference of 1.4 log CFU/g was reported when compared with the vegetables without the protective culture. Moreover, by using two levels of L. monocytogenes (about 6 and 4 log CFU/g), it was observed that the antagonist effect of P. pentosaceus was higher for the lower pathogen numbers. The second approach evaluated a pediocin DT016 solution to inactivate and control L. monocytogenes proliferation. The pathogen load was studied after washing with: water, chlorine and the pediocin solution and along storage at 4  °C. Comparing the various washing solutions, the vegetables washed with pediocin presented significantly (p < 0.01) lower pathogen numbers throughout storage, by a minimum of 3.2 and 2.7 log CFU/g, than in vegetables washed with water and chlorine, respectively. The proposed methodologies are promising alternatives to maintain the safety of fresh vegetables during extended storage at refrigeration temperature.


Asunto(s)
Antibiosis , Microbiología de Alimentos/métodos , Conservación de Alimentos/métodos , Listeria monocytogenes/fisiología , Verduras/microbiología , Carga Bacteriana , Cloro/farmacología , Frío , Seguridad de Productos para el Consumidor , Manipulación de Alimentos/métodos , Lechuga/microbiología , Listeria monocytogenes/efectos de los fármacos , Listeria monocytogenes/crecimiento & desarrollo , Pediocinas/farmacología , Pediococcus pentosaceus/fisiología , Petroselinum/microbiología , Refrigeración , Spinacia oleracea/microbiología , Agua
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