Edible films or coatings could be used as an alternative way of conservation, because of their ability to reduce respiration and transpiration rate, maintain firmness and generally delay fruit ...senescence. The aim of this research was to evaluate the influence of different types of coating: sodium alginate (Al), pectin (Pe) and sodium alginate plus pectin (Al + Pe), on some blueberries quality characteristics, cell viability and microbial growth during 14 days of storage at 4 °C.
Blueberry samples differently coated did not show significant differences in weight loss, pH, soluble solid and dry matter content. However, the application of Al, Pe and Al + Pe improved the firmness of blueberry samples as compared to the uncoated one. Changes in the surface reflection properties in the coated blueberries induced a general lower lightness and a more intense blue hue colour than the control sample. The microbiological results indicated that the coating of blueberry, in particular with Al or Pe, significantly reduced the growth kinetics of yeasts and mesophilic aerobic bacteria.
•Coating induced a decrease of lightness and an increase of blue colour in berries.•Firmness of blueberries was improved by application of coating.•Alginate/pectin coating reduced the growth of yeasts and mesophilic aerobic bacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In late summer 1999, an outbreak of human encephalitis occurred in the northeastern United States that was concurrent with extensive mortality in crows (Corvus species) as well as the deaths of ...several exotic birds at a zoological park in the same area. Complete genome sequencing of a flavivirus isolated from the brain of a dead Chilean flamingo (Phoenicopterus chilensis), together with partial sequence analysis of envelope glycoprotein (E-glycoprotein) genes amplified from several other species including mosquitoes and two fatal human cases, revealed that West Nile (WN) virus circulated in natural transmission cycles and was responsible for the human disease. Antigenic mapping with E-glycoprotein-specific monoclonal antibodies and E-glycoprotein phylogenetic analysis confirmed these viruses as WN. This North American WN virus was most closely related to a WN virus isolated from a dead goose in Israel in 1998.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Aims
The application of essential oils (EOs) and their components as food preservatives is promising but requires a deeper understanding of their mechanisms of action. This study aims to evaluate the ...effects of thyme EO, carvacrol, citral and 2‐(E)‐hexenal, on whole‐genome gene expression (the transcriptome), as well as the fatty acid (FA) composition of the cell membranes of Escherichia coli K12.
Methods and Results
Therefore, we studied the response against 1 h of exposure to sublethal concentrations of natural antimicrobials, of exponentially growing E. coli K12, using DNA microarray technology and a gas chromatographic method. The results show that treatment with a sublethal concentration of the antimicrobials strongly affects global gene expression in E. coli for all antimicrobials used. Major changes in the expression of genes involved in metabolic pathways as well as in FA biosynthesis and protection against oxidative stress were evidenced. Moreover, the sublethal treatments resulted in increased levels of unsaturated and cyclic FAs as well as an increase in the chain length compared to the controls.
Conclusions
The down‐regulation of genes involved in aerobic metabolism indicates a shift from respiration to fermentative growth. Moreover, the results obtained suggest that the cytoplasmic membrane of E. coli is the major cellular target of EOs and their components. In addition, the key role of membrane unsaturated FAs in the response mechanisms of E. coli to natural antimicrobials has been confirmed in this study.
Significance and Impact of the Study
The transcriptomic data obtained signify a further step to understand the mechanisms of action of natural antimicrobials also when sublethal concentrations and short‐term exposure. In addition, this research goes in deep correlating the transcriptomic modification with the changes in E. coli FA composition of cell membrane identified as the main target of the natural antimicrobials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The aim of this study was the evaluation of the effects of pure citral and citron essential oil on microbial spoilage and growth and survival of pathogenic microorganisms during storage. They were ...added in the syrup of industrial ready‐to‐eat fruit salads stored at 9 °C. Both citral (25 to 125 ppm) and citron essential oil (300, 600, 900 ppm) were able to prolong the microbial shelf life of the fruit‐based salads. The essential oil gave excellent results, avoiding the undesirable effects attributable to the cytotoxicity of citral. Citron essential oil doubled the time needed for the wild microflora to reach concentrations able to produce a perceivable spoilage in condition of thermal abuse (9 °C). The same essential oil had reduced effects on the survival of Gram‐negative species Salmonella Enteritidis and Escherichia coli, but showed a strong inhibition toward the Gram‐positive pathogen Listeria monocytogenes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This work aimed to determine the effect of homogenization pressures and addition of trehalose on the functional properties of mandarin juice enriched with Lactobacillus salivarius spp. salivarius. ...Physicochemical and structural properties of mandarin juice were evaluated and related with quantity and stability of probiotic microorganism as well as with its hydrophobicity. Both food matrix and processing, affected functional properties of L. salivarius spp. salivarius. Homogenization pressures and trehalose addition affected quantity and stability of probiotic microorganisms during storage. 20 MPa and 20 MPa with 100 g/kg of trehalose allowed obtaining 106 colony forming units (CFU)/ml mandarin juice after ten storage days. In MRS growth, cell hydrophobicity increased with homogenization pressures, with values in range 67–98%. Highest cell hydrophobicity was obtained in samples homogenized at 100 MPa. Under stress growth conditions, cell hydrophobicity values were in a range 30–84%. In samples no homogenized, addition of trehalose resulted in an increased values of hydrophobicity, with highest levels in those samples with 100 g/kg of trehalose addition.
•L. salivarius has shown a positive effect against all food pathogens tested.•Homogenization at 20 MPa allows obtaining high quantities of microorganism.•Trehalose and homogenization influence stability of probiotic during storage.•In an optimum media homogenization pressures improves probiotic hydrophobicity.•In stress conditions trehalose interactions improve probiotic hydrophobicity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Aim
To characterize four novel autochthonous bifidobacteria isolated from monkey faeces and a Bifidobacterium lactis strain isolated from chicken faeces by evaluating their technological and ...biological/functional potential to be used as probiotics. Different stressors, including food process parameters and storage, can affect their viability and functionality.
Methods and Results
The resistance to frozen storage, tolerance to lyophilization and viability during storage, thermal, acidic and simulated gastric resistance, surface hydrophobicity and antimicrobial activity against pathogens were studied. Bifidobacterium lactis Bb12 and INL1 were used as reference strains. The results obtained demonstrated that the new isolates presented strain‐dependent behaviour. Good results were obtained for thermal resistance, frozen storage at −80°C and lyophilized powders maintained at 5°C. Cell viability during refrigerated storage was higher when the strains were resuspended in milk at pH 5·0 than at 4·5. The surface hydrophobicity ranged between 7 and 98% depending on the strain. The simulated gastric resistance was improved for the strains incorporated in cheese. Regarding antimicrobial activity, bifidobacteria isolated from monkey presented higher inhibitory capacity than the reference strains.
Conclusion
This research provides a deeper insight into new strains of bifidobacteria isolated from primates and chicken that have not been previously characterized for their potential use in dairy products and confirm the most robust stress tolerance of B. lactis.
Significance and Impact of the Study
The possibility of expanding the available bifidobacteria with the potential to be added to a probiotic food necessarily implies characterizing them from different points of view, especially when considering unknown species. For monkey isolates (which showed higher antimicrobial activity against pathogens), more in‐depth knowledge is needed before applying strategies to improve their performance. On the contrary, the chicken isolate B. lactis P32/1 showed similar behaviour to the references B. lactis strains; therefore, it could be considered as a potential probiotic candidate.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The principal aim of this research was to evaluate the ability of different
Yarrowia lipolytica strains, having different origin, to grow in olive mill wastewater (OMW) and reduce its COD level. All ...the strains were able to grow in undiluted OMW; the comparison between the data obtained in a semi-synthetic medium and in OMW suggests that lipases with different specificity can be produced in relation to the medium composition.
Under the adopted conditions, the reduction of the OMW COD values varied from 1.47% and 41.22% of the initial value. Some strains determined a significant reduction of polyphenol content, while other ones caused its apparent increase. Moreover, some
Y. lipolytica strains, isolated from chilled foods, produced the highest citric acid concentrations. These results evidenced that some
Y. lipolytica strains are good candidates for the reduction of the pollution potential of OMW and for the production of enzymes and metabolites such as lipase and citric acid.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Minimally processed fruits are an important area of potential growth in rapidly expanding fresh cut produce. However, the degree of safety obtained with the currently applied preservation methods ...seems to be not sufficient. The interest in the possible use of natural compounds to prevent microbial growth has notably increased in response to the consumer pressure to reduce or eliminate chemically synthesized additives in foods. The aim of this work is to give an overview on the application of natural compounds, such as hexanal, 2-(E)-hexenal, hexyl acetate and citrus essential oils, to improve the shelf-life and the safety of minimally processed fruits as well as their mechanisms of action.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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