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  Subjects -> BIOLOGY (Total: 2691 journals)
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MICROBIOLOGY (224 journals)                  1 2 3     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 6)
Addiction Genetics     Open Access   (Followers: 3)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 16)
Advances in Microbiology     Open Access   (Followers: 16)
Advances in Molecular Imaging     Open Access   (Followers: 3)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
Algorithms for Molecular Biology     Open Access   (Followers: 5)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 14)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 15)
American Journal of Molecular Biology     Open Access   (Followers: 3)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 5)
Annals of Microbiology     Hybrid Journal   (Followers: 9)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 22)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 15)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 24)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 25)
Archives of Microbiology     Hybrid Journal   (Followers: 3)
Avicenna Journal of Clinical Microbiology and Infection     Open Access  
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription  
BioArchitecture     Full-text available via subscription  
Biocell     Open Access   (Followers: 1)
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Research     Open Access   (Followers: 3)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 8)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 1)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 4)
Cell Biology : Research & Therapy     Partially Free  
Cell Host & Microbe     Full-text available via subscription   (Followers: 10)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cell Stem Cell     Full-text available via subscription   (Followers: 19)
CellBio     Open Access  
Cells     Open Access   (Followers: 1)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 8)
Cellular Microbiology     Hybrid Journal   (Followers: 5)
Cellular Senescence and Therapy     Open Access  
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 15)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 3)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 10)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 8)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Continental Journal of Microbiology     Open Access   (Followers: 3)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 6)
Current Issues in Molecular Biology     Open Access  
Current Microbiology     Hybrid Journal   (Followers: 5)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 15)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 4)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 4)
Disease and Molecular Medicine     Open Access   (Followers: 1)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 2)
Environmental Microbiology     Hybrid Journal   (Followers: 8)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 5)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 3)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 11)
European Journal of Microbiology and Immunology     Open Access   (Followers: 6)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 2)
Fems Immunology & Medical Microbiology     Hybrid Journal   (Followers: 6)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 13)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 18)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 12)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 1)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 2)
Frontiers in Cellular Neuroscience     Open Access  
Frontiers in Microbiology     Open Access   (Followers: 5)
Frontiers in Molecular Neuroscience     Open Access  
Future Microbiology     Full-text available via subscription   (Followers: 2)
Future Virology     Full-text available via subscription   (Followers: 4)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access  
Genetics and Molecular Research     Open Access   (Followers: 3)
Geomicrobiology Journal     Hybrid Journal   (Followers: 1)
Gut Microbes     Full-text available via subscription   (Followers: 2)
Indian Journal of Microbiology     Hybrid Journal   (Followers: 1)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 6)
International Arabic Journal of Antimicrobial Agents     Open Access   (Followers: 5)
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 3)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 6)
International Journal of Biotechnology and Molecular Biology Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (Followers: 11)

        1 2 3     

Journal Cover International Journal of Food Microbiology
   [13 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0168-1605
     Published by Elsevier Homepage  [2575 journals]   [SJR: 1.386]   [H-I: 108]
  • Antimicrobial activity of Satureja montana L. essential oil against
           Clostridium perfringens type A inoculated in mortadella-type sausages
           formulated with different levels of sodium nitrite
    • Abstract: Publication date: 5 January 2011
      Source:International Journal of Food Microbiology, Volume 144, Issue 3
      Author(s): Thales Leandro Coutinho de Oliveira , Rodrigo de Araújo Soares , Eduardo Mendes Ramos , Maria das Graças Cardoso , Eduardo Alves , Roberta Hilsdorf Piccoli
      This research evaluated the antimicrobial effect of the winter savory (Satureja montana L.) essential oil (EO) against Clostridium perfringens type A (ATCC 3624) inoculated in mortadella-type sausages formulated with different levels of sodium nitrite (NaNO2: 0ppm, 100ppm and 200ppm) in addition to EO at concentrations of 0.0%, 0.78%, 1.56% and 3.125% stored at 25°C for 30days. The EO extracted by hydrodistillation and analyzed by gas chromatography–mass spectrometry (CG–MS) was tested in vitro using an agar well diffusion method for determination of minimum inhibitory concentration (MIC) on C. perfringens. According to compositional analysis of the winter savory EO, 26 chemical compounds were identified, and the major constituents were thymol (28.99%), p-cymene (12.00%), linalool (11.00%) and carvacrol (10.71%). The results obtained showed that EO applied at a concentration of 1.56%, which was defined as the MIC, exhibited antimicrobial activity against C. perfringens in the in vitro assays, and the transmission electron microscopy (TEM) revealed structural damage and cell lysis of C. perfringens caused by EO treatment. A synergistic effect between NaNO2 and EO was observed. In mortadella-type sausages formulated with 100ppm of NaNO2 and EO at all concentrations tested, the population of target microorganisms was reduced (p ≤0.05) compared to control samples during all storage period. This data suggests the potential combined use of savory EO and minimal amounts of the synthetic additive, NaNO2 to control C. perfringens in mortadella, which goes according to current market trends, where consumers are requesting natural products.
      Highlights ►26 chemical compounds were identified in the EO fraction, and the major constituents were thymol p-cymene, linalool and carvacrol. ►The minimum inhibitory concentration (MIC), of the EO on C. perfringens was 1.56%. ►Transmission electron microscopy revealed structural damage and cell lysis of C. perfringens caused by EO treatment. ►A synergistic effect between NaNO2 and EO on C. perfringens was observed. ►The potential combined use of savory EO and minimal amounts of NaNO2 to control C. perfringens in mortadella appear to be a alternative feasible.

      PubDate: 2014-12-15T17:31:23Z
       
  • The effect of X-ray irradiation on Salmonella inactivation and sensory
           quality of almonds and walnuts as a function of water activity
    • Abstract: Publication date: 15 February 2012
      Source:International Journal of Food Microbiology, Volume 153, Issue 3
      Author(s): Sanghyup Jeong , Bradley P. Marks , Elliot T. Ryser , Janice B. Harte
      The overall goal of this study was to develop a set of process design principles for low-energy X-ray irradiation of tree nuts. Almonds and walnuts were inoculated with Salmonella Enteritidis PT30 and Salmonella Tennessee, and conditioned to four different water activities (0.23, 0.45, 0.64, and 0.84 a w ). Thereafter, the inoculated/conditioned samples were irradiated to achieve up to a 5-log reduction in Salmonella using a pilot scale low-energy X-ray food irradiator. Greater efficacy (D 10-value: the dose required to eliminate 90% of the microbial population) for inactivating SE PT30 and S. Tennessee was seen on the surface of almonds (0.226–0.431kGy) than on walnuts (0.474–0.930kGy) at all water activities. Also, the efficacy did not change monotonically with water activity. Overall, no significant difference (P >0.05) in sensory characteristics was seen between non-irradiated almonds and those irradiated to achieve a 5 log reduction in Salmonella. However, irradiating walnuts to the dose corresponding to a 5 log reduction caused a perceivable change in flavor. Post-irradiation storage tests revealed that surviving bacterial counts did not change over 120days, regardless of nut type, Salmonella serovar, and a w . Therefore, low-energy X-ray irradiation technology appears to be a promising non-thermal pasteurization strategy for certain types of nuts.
      Highlights ► Microbial efficacy of X-ray for Salmonella on almonds and walnuts was measured. ► Radiation resistance (D10-value) did not change monotonically with water activity. ► Sensory changes of almonds at the 5 log reduction X-ray dose were not significant. ► Post-irradiation bacterial counts did not change over 120 days of storage.

      PubDate: 2014-12-15T17:31:23Z
       
  • Mixed species biofilms of Listeria monocytogenes and Lactobacillus
           plantarum show enhanced resistance to benzalkonium chloride and peracetic
           acid
    • Abstract: Publication date: 5 January 2011
      Source:International Journal of Food Microbiology, Volume 144, Issue 3
      Author(s): Stijn van der Veen , Tjakko Abee
      We investigated the formation of single and mixed species biofilms of Listeria monocytogenes strains EGD-e and LR-991, with Lactobacillus plantarum WCFS1 as secondary species, and their resistance to the disinfectants benzalkonium chloride and peracetic acid. Modulation of growth, biofilm formation, and biofilm composition was achieved by addition of manganese sulfate and/or glucose to the BHI medium. Composition analyses of the mixed species biofilms using plate counts and fluorescence microscopy with dual fluorophores showed that mixed species biofilms were formed in BHI (total count, 8-9 log10 cfu/well) and that they contained 1-2 log10 cfu/well more L. monocytogenes than L. plantarum cells. Addition of manganese sulfate resulted in equal numbers of both species (total count, 8 log10 cfu/well) in the mixed species biofilm, while manganese sulfate in combination with glucose, resulted in 1-2 log10 more L. plantarum than L. monocytogenes cells (total count, 9 log10 cfu/well). Corresponding single species biofilms of L. monocytogenes and L. plantarum contained up to 9 log10 cfu/well. Subsequent disinfection treatments showed mixed species biofilms to be more resistant to treatments with the selected disinfectants. In BHI with additional manganese sulfate, both L. monocytogenes strains and L. plantarum grown in the mixed species biofilm showed less than 2 log10 cfu/well inactivation after exposure for 15min to 100μg/ml benzalkonium chloride, while single species biofilms of both L. monocytogenes strains showed 4.5 log10 cfu/well inactivation and single species biofilms of L. plantarum showed 3.3 log10 cfu/well inactivation. Our results indicate that L. monocytogenes and L. plantarum mixed species biofilms can be more resistant to disinfection treatments than single species biofilms.
      Highlights ►Listeria monocytogenes and Lactobacillus plantarum form mixed species biofilms. ►Single species biofilms are more resistant than planktonic cells. ►Mixed species biofilms are more resistance than single species biofilms.

      PubDate: 2014-12-15T17:31:23Z
       
  • Food fermentations: Microorganisms with technological beneficial use
    • Abstract: Publication date: 15 March 2012
      Source:International Journal of Food Microbiology, Volume 154, Issue 3
      Author(s): François Bourdichon , Serge Casaregola , Choreh Farrokh , Jens C. Frisvad , Monica L. Gerds , Walter P. Hammes , James Harnett , Geert Huys , Svend Laulund , Arthur Ouwehand , Ian B. Powell , Jashbhai B. Prajapati , Yasuyuki Seto , Eelko Ter Schure , Aart Van Boven , Vanessa Vankerckhoven , Annabelle Zgoda , Sandra Tuijtelaars , Egon Bech Hansen
      Microbial food cultures have directly or indirectly come under various regulatory frameworks in the course of the last decades. Several of those regulatory frameworks put emphasis on “the history of use”, “traditional food”, or “general recognition of safety”. Authoritative lists of microorganisms with a documented use in food have therefore come into high demand. One such list was published in 2002 as a result of a joint project between the International Dairy Federation (IDF) and the European Food and Feed Cultures Association (EFFCA). The “2002 IDF inventory” has become a de facto reference for food cultures in practical use. However, as the focus mainly was on commercially available dairy cultures, there was an unmet need for a list with a wider scope. We present an updated inventory of microorganisms used in food fermentations covering a wide range of food matrices (dairy, meat, fish, vegetables, legumes, cereals, beverages, and vinegar). We have also reviewed and updated the taxonomy of the microorganisms used in food fermentations in order to bring the taxonomy in agreement with the current standing in nomenclature.
      Highlights ► Up to date inventory of microbial species used in production of fermented foods. ► The inventory covers species of starter cultures and “natural floras”. ► Species with a documented beneficial technological purpose are included. ► We present a history of use also for newly established taxonomic units. ► The inventory consists of 195 bacterial species and 69 species of yeasts and molds.

      PubDate: 2014-12-15T17:31:23Z
       
  • Mapping the structural requirements of inducers and substrates for
           decarboxylation of weak acid preservatives by the food spoilage mould
           Aspergillus niger
    • Abstract: Publication date: 16 July 2012
      Source:International Journal of Food Microbiology, Volume 157, Issue 3
      Author(s): Malcolm Stratford , Andrew Plumridge , Mike W. Pleasants , Michaela Novodvorska , Charles A.G. Baker-Glenn , Gerald Pattenden , David B. Archer
      Moulds are able to cause spoilage in preserved foods through degradation of the preservatives using the Pad-decarboxylation system. This causes, for example, decarboxylation of the preservative sorbic acid to 1,3-pentadiene, a volatile compound with a kerosene-like odour. Neither the natural role of this system nor the range of potential substrates has yet been reported. The Pad-decarboxylation system, encoded by a gene cluster in germinating spores of the mould Aspergillus niger, involves activity by two decarboxylases, PadA1 and OhbA1, and a regulator, SdrA, acting pleiotropically on sorbic acid and cinnamic acid. The structural features of compounds important for the induction of Pad-decarboxylation at both transcriptional and functionality levels were investigated by rtPCR and GCMS. Sorbic and cinnamic acids served as transcriptional inducers but ferulic, coumaric and hexanoic acids did not. 2,3,4,5,6-Pentafluorocinnamic acid was a substrate for the enzyme but had no inducer function; it was used to distinguish induction and competence for decarboxylation in combination with the analogue chemicals. The structural requirements for the substrates of the Pad-decarboxylation system were probed using a variety of sorbic and cinnamic acid analogues. High decarboxylation activity, ~100% conversion of 1mM substrates, required a mono-carboxylic acid with an alkenyl double bond in the trans (E)-configuration at position C2, further unsaturation at C4, and an overall molecular length between 6.5Å and 9Å. Polar groups on the phenyl ring of cinnamic acid abolished activity (no conversion). Furthermore, several compounds were shown to block Pad-decarboxylation. These compounds, primarily aldehyde analogues of active substrates, may serve to reduce food spoilage by moulds such as A. niger. The possible ecological role of Pad-decarboxylation of spore self-inhibitors is unlikely and the most probable role for Pad-decarboxylation is to remove cinnamic acid-type inhibitors from plant material and allow uninhibited germination and growth of mould spores.
      Highlights ► The Pad-decarboxylation system in germinating spores of Aspergillus niger degrades food preservatives. ► Decarboxylation required a carboxylic acid with an alkenyl double bond at C2 and C4. ► 2,3,4,5,6-Pentafluorocinnamic acid was a substrate but had no inducer function. ► Several compounds block decarboxylation and may serve to reduce food spoilage by moulds.

      PubDate: 2014-12-15T17:31:23Z
       
  • Decontamination efficiency of high power ultrasound in the fruit and
           vegetable industry, a review
    • Abstract: Publication date: 16 August 2013
      Source:International Journal of Food Microbiology, Volume 166, Issue 1
      Author(s): Seda Ersus Bilek , Fulya Turantaş
      Decontamination of fresh fruits and vegetables is an important unsolved technological problem. The main focus of this review is to summarize and synthesize the results of studies and articles about ultrasonic processing which can be adapted to the wash water decontamination process for fruits and vegetables. This review will also provide an overview about the importance of an effective wash water decontamination process in fruits and vegetables, the increase of foodborne outbreaks caused by fresh fruits and vegetables, microbial inactivation using ultrasound, and an interpretation of the high power ultrasound results in the fruits and vegetable industry. In addition, the limitations of ultrasonic processing in commercial applications have also been introduced.


      PubDate: 2014-12-15T17:31:23Z
       
  • Extreme resistance to weak-acid preservatives in the spoilage yeast
           Zygosaccharomyces bailii
    • Abstract: Publication date: 16 August 2013
      Source:International Journal of Food Microbiology, Volume 166, Issue 1
      Author(s): Malcolm Stratford , Hazel Steels , Gerhard Nebe-von-Caron , Michaela Novodvorska , Kimran Hayer , David B. Archer
      Weak-acid preservatives, such as sorbic acid and acetic acid, are used in many low pH foods to prevent spoilage by fungi. The spoilage yeast Zygosaccharomyces bailii is notorious for its extreme resistance to preservatives and ability to grow in excess of legally-permitted concentrations of preservatives. Extreme resistance was confirmed in 38 strains of Z. bailii to several weak-acid preservatives. Using the brewing yeast Saccharomyces cerevisiae as a control, tests showed that Z. bailii was ~3-fold more resistant to a variety of weak-acids but was not more resistant to alcohols, aldehydes, esters, ethers, ketones, or hydrophilic chelating acids. The weak acids were chemically very diverse in structure, making it improbable that the universal resistance was caused by degradation or metabolism. Examination of Z. bailii cell populations showed that extreme resistance to sorbic acid, benzoic acid and acetic acid was limited to a few cells within the population, numbers decreasing with concentration of weak acid to <1 in 1000. Re-inoculation of resistant sub-populations into weak-acid-containing media showed that all cells now possessed extreme resistance. Resistant sub-populations grown in any weak-acid preservative also showed ~100% cross-resistance to other weak-acid preservatives. Tests using 14C-acetic acid showed that weak-acid accumulation was much lower in the resistant sub-populations. Acid accumulation is caused by acid dissociation in the higher pH of the cytoplasm. Tests on intracellular pH (pHi) in the resistant sub-population showed that the pH was much lower, ~ pH5.6, than in the sensitive bulk population. The hypothesis is proposed that extreme resistance to weak-acid preservatives in Z. bailii is due to population heterogeneity, with a small proportion of cells having a lower intracellular pH. This reduces the level of accumulation of any weak acid in the cytoplasm, thus conferring resistance to all weak acids, but not to other inhibitors.


      PubDate: 2014-12-15T17:31:23Z
       
  • Modeling the influence of temperature, water activity and water mobility
           on the persistence of Salmonella in low-moisture foods
    • Abstract: Publication date: 2 September 2013
      Source:International Journal of Food Microbiology, Volume 166, Issue 2
      Author(s): S.M. Santillana Farakos , J.F. Frank , D.W. Schaffner
      Salmonella can survive in low-moisture foods for long periods of time. Reduced microbial inactivation during heating is believed to be due to the interaction of cells and water, and is thought to be related to water activity (aw ). Little is known about the role of water mobility in influencing the survival of Salmonella in low-moisture foods. The aim of this study was to determine how the physical state of water in low-moisture foods influences the survival of Salmonella and to use this information to develop mathematical models that predict the behavior of Salmonella in these foods. Whey protein powder of differing water mobilities was produced by pH adjustment and heat denaturation, and then equilibrated to aw levels between 0.19±0.03 and 0.54±0.02. Water mobility was determined by wide-line proton-NMR. Powders were inoculated with a four-strain cocktail of Salmonella, vacuum-sealed and stored at 21, 36, 50, 60, 70 and 80°C. Survival data was fitted to the log-linear, the Geeraerd-tail, the Weibull, the biphasic-linear and the Baranyi models. The model with the best ability to describe the data over all temperatures, water activities and water mobilities (ftest < Ftable ) was selected for secondary modeling. The Weibull model provided the best description of survival kinetics for Salmonella. The influence of temperature, aw and water mobility on the survival of Salmonella was evaluated using multiple linear regression. Secondary models were developed and then validated in dry non-fat dairy and grain, and low-fat peanut and cocoa products within the range of the modeled data. Water activity significantly influenced the survival of Salmonella at all temperatures, survival increasing with decreasing aw . Water mobility did not significantly influence survival independent of aw . Secondary models were useful in predicting the survival of Salmonella in various low-moisture foods providing a correlation of R =0.94 and an acceptable prediction performance of 81%. The % bias and % discrepancy results showed that the models were more accurate in predicting survival in non-fat food systems as compared to foods containing low-fat levels (12% fat). The models developed in this study represent the first predictive models for survival of Salmonella in low-moisture foods. These models provide baseline information to be used for research on risk mitigation strategies for low-moisture foods.


      PubDate: 2014-12-15T17:31:23Z
       
  • Survival of foodborne pathogens on inshell walnuts
    • Abstract: Publication date: 16 September 2013
      Source:International Journal of Food Microbiology, Volume 166, Issue 3
      Author(s): Tyann Blessington , Christopher G. Theofel , Elizabeth J. Mitcham , Linda J. Harris
      The survival of Salmonella enterica Enteritidis PT 30 or five-strain cocktails of S. enterica, Escherichia coli O157:H7, and Listeria monocytogenes was evaluated on inshell walnuts during storage. Inshell walnuts were separately inoculated with an aqueous preparation of the pathogens at levels of 10 to 4log CFU/nut, dried for 24h, and then stored at either 4°C or ambient conditions (23–25°C, 25–35% relative humidity) for 3weeks to more than 1year. During the initial 24-h drying period, bacterial levels declined by 0.7 to 2.4log CFU/nut. After the inoculum dried, further declines of approximately 0.1log CFU/nut per month of Salmonella Enteritidis PT 30 levels were observed on inshell walnuts stored at 4°C; at ambient conditions the rates of decline ranged from 0.55 to 2.5log CFU/nut per month. Rates of decline were generally greater during the first few weeks of storage, particularly at lower inoculum levels. The survival of the five-strain cocktails inoculated at very low levels (under 400CFU/nut) was determined during storage at ambient conditions. The pathogens could be recovered by either enumeration or enrichment from most samples throughout the 3-month storage period; reductions in bacterial levels from the beginning to end of storage were 0.7, 0.2, and 2.3log CFU/nut for Salmonella, E. coli O157:H7, and L. monocytogenes, respectively. For 6% of all nut samples (14 of 234 samples), pathogens were isolated from the second but not first 24-h enrichment, suggesting that bacterial cells were viable but not easily culturable. Salmonella-inoculated walnuts were exposed for 2min to water or a 3% solution of sodium hypochlorite (to mimic commercial brightening) either 24h or 7days after inoculation; treated nuts were dried for 24h and held at ambient conditions. Salmonella levels were reduced by less than 0.5log or 2.4 to 2.6log CFU/nut on water– or chlorine– treated walnuts, respectively, regardless of postinoculation treatment time. Additional reductions of 2.6 and 2.1log CFU/nut were observed for water- and chlorine-treated walnuts, respectively, after storage for 2weeks at ambient conditions. Bacterial foodborne pathogens are capable of long-term survival on the surface of inshell walnuts even when initial levels are low.


      PubDate: 2014-12-15T17:31:23Z
       
  • Combination effect of ozone and heat treatments for the inactivation of
           Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria
           monocytogenes in apple juice
    • Abstract: Publication date: 3 February 2014
      Source:International Journal of Food Microbiology, Volume 171
      Author(s): Hye-Jung Sung , Won-Jae Song , Kwang-Pyo Kim , Sangryeol Ryu , Dong-Hyun Kang
      We investigated the combination effect of ozone and heat treatments in apple juice for the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes. Apple juices inoculated with the three pathogens were treated with gaseous ozone and heat simultaneously for up to 1min. Gaseous ozone treatment was progressed at a flow rate of 3.0l/min with a concentration of 2.0–3.0g/m3 and heat treatment was performed at temperatures of 25, 45, 50, and 55°C. Populations of surviving pathogens decreased in all samples as treatment temperature increased from 25 to 55°C. Heat treatment alone (25, 45, 50 and 55°C) resulted in 0.20, 0.37, 2.16 and 2.54logCFU/ml reductions of E. coli O157:H7, respectively, in apple juice. Combination treatment of ozone and heat for 1min reduced this pathogen by 1.50 and 1.60logCFU/ml, respectively, at 25 and 45°C, and below the detection limit (1logCFU/ml) at 50 and 55°C. We found a synergistic effect in the inactivation of pathogens in apple juice treated with ozone and heated at 50°C. The reduction trend of S. Typhimurium and L. monocytogenes in apple juice was similar to that of E. coli O157:H7. There were no significant changes of Hunter color values when apple juices were treated with heat only and the combination of ozone and heat. Residual ozone was measured following ozone treatment. In all ozone treated samples, the concentration of residual ozone was reduced to under acceptable levels (<0.4mg/l). In conclusion, the combination treatment of ozone and heat was significantly effective in the inactivation of foodborne pathogens while maintaining acceptable apple juice quality.


      PubDate: 2014-12-15T17:31:23Z
       
  • Characterization of plant-derived lactococci on the basis of their
           volatile compounds profile when grown in milk
    • Abstract: Publication date: 17 February 2014
      Source:International Journal of Food Microbiology, Volume 172
      Author(s): Debebe Alemayehu , John A. Hannon , Olivia McAuliffe , R. Paul Ross
      A total of twelve strains of lactococci were isolated from grass and vegetables (baby corn and fresh green peas). Ten of the isolates were classified as Lactococcus lactis subsp. lactis and two as Lactococcus lactis subsp. cremoris based on 16S rDNA sequencing. Most of the plant-derived strains were capable of metabolising a wide range of carbohydrates in that they fermented D-mannitol, amygdalin, potassium gluconate, l-arabinose, d-xylose, sucrose and gentibiose. None of the dairy control strains (i.e. L. lactis subsp. cremoris HP, L. lactis subsp. lactis IL1403 and Lactococcus lactis 303) were able to utilize any of these carbohydrates. The technological potential of the isolates as flavour-producing lactococci was evaluated by analysing their growth in milk and their ability to produce volatile compounds using solid phase micro-extraction of the headspace coupled to gas chromatography–mass spectrometry (SPME GC–MS). Principal component analysis (PCA) of the volatile compounds clearly separated the dairy strains from the plant derived strains, with higher levels of most flavour rich compounds. The flavour compounds produced by the plant isolates among others included; fatty acids such as 2- and 3-methylbutanoic acids, and hexanoic acid, several esters (e.g. butyl acetate and ethyl butanoate) and ketones (e.g. acetoin, diacetyl and 2-heptanone), all of which have been associated with desirable and more mature flavours in cheese. As such the production of a larger number of volatile compounds is a distinguishing feature of plant-derived lactococci and might be a desirable trait for the production of dairy products with enhanced flavour and/or aroma.


      PubDate: 2014-12-15T17:31:23Z
       
  • The prevalence and impact of Fusarium head blight pathogens and mycotoxins
           on malting barley quality in UK
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): L.K. Nielsen , D.J. Cook , S.G. Edwards , R.V. Ray
      Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley.


      PubDate: 2014-12-15T17:31:23Z
       
  • Selection of non-Saccharomyces yeast strains for reducing alcohol levels
           in wine by sugar respiration
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Manuel Quirós , Virginia Rojas , Ramon Gonzalez , Pilar Morales
      Respiration of sugars by non-Saccharomyces yeasts has been recently proposed for lowering alcohol levels in wine. Development of industrial fermentation processes based on such an approach requires, amongst other steps, the identification of yeast strains which are able to grow and respire under the relatively harsh conditions found in grape must. This work describes the characterization of a collection of non-Saccharomyces yeast strains in order to identify candidate yeast strains for this specific application. It involved the estimation of respiratory quotient (RQ) values under aerated conditions, at low pH and high sugar concentrations, calculation of yields of ethanol and other relevant metabolites, and characterization of growth responses to the main stress factors found during the first stages of alcoholic fermentation. Physiological features of some strains of Metschnikowia pulcherrima or two species of Kluyveromyces, suggest they are suitable for lowering ethanol yields by respiration. The unsuitability of Saccharomyces cerevisiae strains for this purpose was not due to ethanol yields (under aerated conditions they are low enough for a significant reduction in final ethanol content), but to the high acetic acid yields under these growth conditions. According to results from controlled aeration fermentations with one strain of M. pulcherrima, design of an aeration regime allowing for lowering ethanol yields though preserving grape must components from excessive oxidation, would be conceivable.


      PubDate: 2014-12-15T17:31:23Z
       
  • Enteric porcine viruses in farmed shellfish in Denmark
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186
      Author(s): J.S. Krog , L.E. Larsen , A.C. Schultz
      Bivalve shellfish are at constant risk of being exposed to pathogens as a consequence of contamination of the shellfish beds with human or animal waste originating from sewage treatment plants or slurry fertilized fields. Consumption of contaminated oysters and mussels are frequently reported as causes of disease outbreaks caused by norovirus or hepatitis A virus. Other zoonotic pathogens such as hepatitis E virus (HEV), rotavirus (RV) and Salmonella from livestock may also be transmitted to shellfish via this route. In this study, 29 pooled samples from commercial Danish blue mussels were tested for porcine pathogens and indicator bacteria Escherichia coli (E. coli). All samples tested negative for HEV, RV and Salmonella, whereas E. coli and the highly stable porcine circovirus type 2 (PCV2) were detected in eight and 12 samples, respectively. This is the first study to report the detection of PCV2 in commercial mussels. Based on the detection of PCV2 in clean areas with low prevalence of the normally applied fecal indicator E. coli, testing for PCV2 may be a more sensitive and robust specific porcine waste indicator in shellfish harvesting areas.


      PubDate: 2014-12-15T17:31:23Z
       
  • Population heterogeneity and dynamics in starter culture and lag phase
           adaptation of the spoilage yeast Zygosaccharomyces bailii to weak acid
           preservatives
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Malcolm Stratford , Hazel Steels , Gerhard Nebe-von-Caron , Simon V. Avery , Michaela Novodvorska , David B. Archer
      The food spoilage yeast Zygosaccharomyces bailii shows great resistance to weak-acid preservatives, including sorbic acid (2, 4-hexadienoic acid). That extreme resistance was shown to be due to population heterogeneity, with a small sub-population of cells resistant to a variety of weak acids, probably caused by a lower internal pH reducing the uptake of all weak acids. In the present paper, it was found that resistant cells were extremely rare in exponential cultures, but increased by up to 8000-fold in stationary phase. Inoculation of media containing sorbic acid with a population of Z. bailii cells gave rise to what appeared to be a prolonged lag phase, suggesting adaptation to the conditions before the cells entered the period of exponential growth. However, the apparent lag phase caused by sorbic acid was largely due to the time required for the resistant sub-population to grow to detectable levels. The slow growth rate of the sub-population was identical to that of the final total population. The non-resistant bulk population remained viable for 3days but had lost viability by 6days and, during that time, there was no indication of any development of resistance in the bulk population. The sub-population growing in sorbic acid showed very high population diversity in colony size and internal pH. After removal of sorbic acid, the population rapidly reverted back to the normal, largely non-resistant, population distribution. The data presented suggest that a reevaluation of the lag phase in microbial batch culture is required, at least for the resistance of Z. bailii to sorbic acid. Furthermore, the significance of phenotypic diversity and heterogeneity in microbial populations is discussed more broadly with potential relevance to bacterial “persisters”, natural selection and evolution.


      PubDate: 2014-12-15T17:31:23Z
       
  • First description of PVL-positive methicillin-resistant Staphylococcus
           aureus (MRSA) in wild boar meat
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186
      Author(s): Britta Kraushaar , Alexandra Fetsch
      Staphylococcus aureus is an important food-borne pathogen due to the ability of enterotoxigenic strains to produce staphylococcal enterotoxins (SEs) in food. Methicillin-resistant S. aureus (MRSA) is also an important pathogen for humans, causing severe and hard to treat diseases in hospitals and in the community due to its multiresistance against antimicrobials. In particular, strains harbouring genes encoding for the Panton–Valentine leukocidin (PVL) toxin are of concern from a public health perspective as they are usually capable of causing severe skin and soft tissue infections (sSSTIs) and occasionally necrotizing pneumonia which is associated with high mortality. This is the first report on the detection of MRSA with genes encoding for PVL in wild boar meat. Among the 28 MRSA isolated from wild boar meat in the course of a national monitoring programme in Germany, seven harboured PVL-encoding genes. Six of the isolates were identical according to the results of spa-, MLST-, microarray- and PFGE-typing. They could be assigned to the epidemic MRSA clone USA300. Epidemiological investigations revealed that people handling the food were the most likely common source of contamination with these MRSA. These findings call again for suitable hygienic measures at all processing steps of the food production chain. The results of the study underline that monitoring along the food chain is essential to closely characterise the total burden of MRSA for public health.


      PubDate: 2014-12-15T17:31:23Z
       
  • Biocontrol activity of four non- and low-fermenting yeast strains against
           Aspergillus carbonarius and their ability to remove ochratoxin A from
           grape juice
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Stefano Fiori , Pietro Paolo Urgeghe , Walid Hammami , Salvatorico Razzu , Samir Jaoua , Quirico Migheli
      Aspergillus spp. infection of grape may lead to ochratoxin A (OTA) contamination in processed beverages such as wine and grape juice. The aim of the current study was to evaluate the biocontrol potential of two non-fermenting (Cyberlindnera jadinii 273 and Candida friedrichii 778) and two low-fermenting (Candida intermedia 235 and Lachancea thermotolerans 751) yeast strains against the pathogenic fungus and OTA-producer Aspergillus carbonarius, and their ability to remove OTA from grape juice. Two strains, 235 and 751, showed a significant ability to inhibit A. carbonarius both on grape berries and in in vitro experiments. Neither their filtrate nor their autoclaved filtrate culture broth was able to prevent consistently pathogen growth. Volatile organic compounds (VOCs) produced by all four selected yeasts were likely able to consistently prevent pathogen sporulation in vitro. VOCs produced by the non-fermenting strain 778 also significantly reduced A. carbonarius vegetative growth. Three yeast strains (235, 751, and 778) efficiently adsorbed artificially spiked OTA from grape juice, while autoclaving treatment improved OTA adsorption capacity by all the four tested strains. Biological control of A. carbonarius and OTA-decontamination using yeast is proposed as an approach to meet the Islamic dietary laws concerning the absence of alcohol in halal beverages.


      PubDate: 2014-12-15T17:31:23Z
       
  • Fast and discriminative CoSYPS detection system of viable Salmonella spp.
           and Listeria spp. in carcass swab samples
    • Abstract: Publication date: 2 January 2015
      Source:International Journal of Food Microbiology, Volume 192
      Author(s): Elodie Barbau-Piednoir , Nadine Botteldoorn , Jacques Mahillon , Katelijne Dierick , Nancy H. Roosens
      In this study, the complete CoSYPS Path Food workflow including all steps, namely swab sample enrichment, SYBR®Green qPCR detection of Salmonella spp. and Listeria spp., isolation and confirmation of the detected strain, was validated on beef carcass swabs. To perform the validation, the results of the complete workflow were compared, according to the ISO 16140:2003, with the ISO reference methods for detection, isolation and confirmation of Listeria monocytogenes and Salmonella spp. The results showed that the relative level of detection and the limit of detection of the complete workflow and ISO reference methods are in a range from 2 to 16CFU/swab for both bacteria. The relative specificity, sensitivity and accuracy identified during this validation were all 100% since the results obtained with the complete CoSYPS Path Food workflow and the ISO reference methods were identical (Cohen's kappa index=1.00). In addition the complete CoSYPS Path Food workflow is able to provide detection results (negative or presumptive positive) in half the time needed as for the ISO reference methods. These results demonstrate that the performance of the complete CoSYPS Path Food workflow is not only comparable to the ISO reference methods but also provides a faster response for the verification of beef carcasses before commercial distribution.


      PubDate: 2014-12-15T17:31:23Z
       
 
 
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