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Glass-ceramic nanopowder with a composition of 55SiO2-35CaO-10MgO (mol %) was synthesized by the sol–gel method and was heat treated at three temperatures (T1 = 835 °C, T2 = 1000 °C, T3 = 1100 °C) in order to obtain different materials (C1, C2, C3, respectively) varying in crystal structure. Bioactivity and oxidative stress were evaluated in simulated body fluid (SBF) for various time periods (up to 10 days). The structure of the synthesized materials and their apatite-forming ability were investigated by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The antibacterial properties of the synthesized materials were evaluated against three Gram-positive and four Gram-negative bacterial strains and their biocompatibility was verified on a primary cell line of human gingival fibroblasts (HGFs) by the MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay. The crystallization of the materials was increased by sintering temperature. Heat treatment did not inhibit the bioactive behavior of the materials as apatite formation started after 3 days in SBF. C2, C3 showed some indications of apatite forming even from the first day. Regarding cell viability, a variety of biological behaviors, concerning both dose and time points, was observed between the positive control and the tested materials by both the MTT assay and oxidative stress analysis. In conclusion, the nanobioceramic materials of this study possess a multitude of attractive physicochemical and biological properties that make them suitable candidates for bone regeneration applications, fillers in nanocomposite scaffolds, or as grafts in bone cavities and periodontal lesions.

Greece is a country possessing many cheese products granted with a PDO (Protected Designation of Origin) certificate, with high exporting activities. In this study, we analyzed six popular cheese PDO products purchased from different industries to assess their microbial communities using amplicon metabarcoding analysis. To this end, using Next Generation Sequencing technology, we sequenced the 16S rRNA gene and the ITS spacer for prokaryotes and fungi, respectively. Alpha diversity indices revealed higher bacterial species richness for some cheeses (Kopanisti, Batzos) and poor for others (Feta, Galotiri). Kopanisti, together with Kalathaki and Anevato, also presented increased species diversity concerning fungal populations. Results showed that lactic acid bacteria (LAB) prevailed the bacterial populations in all samples (Lactococcus, Lactobacillus, Streptococcus, Leuconostoc), whereas for fungi, members of the Saccharomycetaceae, Dipodascaceae and Debaryomycetaceae families prevailed the fungal populations. Several other genera were identified that make up each product's microbiome leading to the creation of the unique organoleptic attributes of Greek PDO cheeses. However, the identified species could not be directly linked to certain cheese types, assuming that starter and adjunct cultures, combined with the raw material used during production greatly impact the microbial communities in cheeses. Our data, produced for the first time for six Greek PDO cheeses, can be exploited in the process of creating a core microbial signature within each cheese type, supporting the Greek brand name and valorizing cheese products.

The microbiological characteristics of Greek Protected Designation of Origin (PDO) cheeses were determined and isolated bacteria were investigated. Six cheese types were examined: Anevato, Batzos, Feta, Galotyri, Kalathaki Limnou and Kopanisti. The highest levels of faecal indicator bacteria, presumptive Listeria spp. and presumptive Staphylococcus aureus were all recorded in Batzos cheese, and the lowest in Feta and Kopanisti. Of the 35 isolates examined with 16S rRNA sequencing, 26 were Lactobacillus spp., eight were Enterococcus spp. and one was Pediococcus parvulus. Of 30 isolates investigated, 86.7% grew well on galactooligosaccharides, while 66.7% grew well on fructooligosaccharides. Cell-free culture supernatants (pH 6) of 14 isolates were inhibitory against some or all of Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli. This research demonstrates that Greek PDO cheeses are of variable microbiological quality and are a rich source of potentially useful bacteria that can be used as antimicrobial synbiotics or biopreservative cultures.

Calcium magnesium silicate glasses could be suggested for the synthesis of scaffolds for hard tissue regeneration, as they present a high residual glassy phase, high hardness values and hydroxyapatite-forming ability. The use of trace elements in the human body, such as Cu, could improve the biological performance of such glasses, as Cu is known to play a significant role in angiogenesis. Nano-bioceramics are preferable compared to their micro-scale counterparts, because of their increased surface area, which improves both mechanical properties and apatite-forming ability due to the increased nucleation sites provided, their high diffusion rates, reduced sintering time or temperature, and high mechanical properties. The aim of the present work was the evaluation of the effect of different ratios of Ethanol/TEOS and total amount of the inserted ammonia to the particle size, morphology and bioactive, hemolytic and antibacterial behavior of nanoparticles in the quaternary system SiO2-CaO-MgO-CuO. Different ratios of Ethanol/TEOS and ammonia amount affected the size and morphology of bioactive nanopowders. The optimum materials were synthesized with the highest ethanol/TEOS ratio and ammonia amount as verified by the enhanced apatite-forming ability and antibacterial and non-hemolytic properties.

A strain of Lactobacillus kefiri, isolated from kefir grains and identified by DNA sequencing, was examined for properties associated with probiotic bacteria. The strain was fully resistant to bile at 0.4% (w/v), but showed only moderate resistance to acid. It grew well on media supplemented with prebiotic compounds (two fructooligosaccharides, galactooligosaccharide (GOS) and lactulose) and significant inactivation of Listeria monocytogenes was observed when GOS was added to the co-culture medium, whereas Escherichia coli was not significantly affected. The data suggested that acidification was not the sole cause of the inactivation, as similar decreases in pH with other prebiotics did not result in comparable inactivation of L. monocytogenes. Lb. kefiri isolated from kefir grains in the present work shows potential as a probiotic, which is a first step towards the development of a functional product. The present data indicate that it would be most effective in a synbiotic combination with GOS.

The survival and growth of Listeria monocytogenes on fresh lettuce (Lactuca sativa), cucumber (Cucumis sativus) epidermis and parsley (Petroselinum sativum) under different relative humidity (RH) conditions and storage temperatures was studied. Inoculated vegetable pieces were stored at 10C for 7 days, 20C for 5 days, and 30C for 24 h, and at 53 and 90% RH. L. monocytogenes was enumerated periodically by plate count. L. monocytogenes did not grow on lettuce or parsley, but either declined in number or remained approximately constant. At cooler temperatures, a negative effect of low humidity on survival was observed. L. monocytogenes grew on cucumber epidermis at all three temperatures, increasing from around 4.0 to around 5.5 log cfu/cm2 when stored at 90% RH. Low RH negatively affected growth, limiting the increase to around 0.5 log cfu/cm2 in most cases. Practical Applications Fresh vegetables are increasingly important vehicles of foodborne pathogens. The majority of published studies on growth and survival of Listeria monocytogenes on vegetables have been conducted on lettuce leaves and few data are available on the influence of relative humidity (RH). Growth of L. monocytogenes may increase the risk to the consumer of some types of fresh vegetables. Maintaining lower RH during storage can decrease this risk, but may conflict with other product quality requirements. L. monocytogenes does not grow on undamaged leaf surfaces under the conditions tested: when reviewing the literature it is important to differentiate between whole and shredded/cut leaves.

Probiotic bacteria and prebiotic compounds can inhibit foodborne pathogenic bacteria or reduce their ability to infect the host, and therefore they can potentially contribute to reducing the frequency and severity of foodborne disease. Probiotics can reduce the carriage of foodborne pathogens by food animals, thereby decreasing the pathogen load entering the human food chain. They can also be applied as starter cultures or protective cultures in certain foods to help eliminate contaminating pathogens. Animal models have been used to determine the antimicrobial efficacy of probiotics against specific pathogens in vivo (due to the difficulty in conducting human trials with pathogenic microorganisms) and demonstrated significant inhibition in some cases. Human clinical trials have focused on acute infectious diarrhea, particularly in infants, and traveler’s diarrhea. Results are variable, and statistical power is often inadequate even for trials with positive results, but there is good evidence to support the use of certain probiotics, notably Saccharomyces boulardii and Lactobacillus rhamnosus GG, for the prevention and treatment of diarrhea.

The efficacy of household decontamination methods at reducing Listeria monocytogenes on fresh lettuce (Lactuca sativa), cucumber (Cucumis sativus) and parsley (Petroselinum sativum) was studied. Inoculated vegetable pieces were immersed in washing solutions and surviving L. monocytogenes enumerated. Parameters investigated were storage temperature prior to washing, dipping water temperature, agitation, acetic acid concentration and immersion time. The results indicated that the storage temperature significantly affects the efficacy of dipping vegetables in water for the control of L. monocytogenes, as the reduction in count was greatest when products had been stored at cooler temperatures. Decontamination with acetic acid (up to 2.0% v/v) was shown to have some effect in most cases, but the highest observed decrease in count was 2.6 log cfu/g. Experiments investigating the effect of exposure time to acetic acid (0.5% and 1.0% v/v, up to 30 min immersion) indicated that immersing the vegetables for more than 10 min is of minimal benefit. The most significant factor affecting washing and decontamination efficacy was the vegetable itself: L. monocytogenes colonizing cucumber epidermis was far more resistant to removal by washing and to acid treatment than that on the leafy vegetables, and L. monocytogenes on parsley was the most susceptible. This shows that published decontamination experiments (often performed with lettuce) cannot necessarily be extrapolated to other vegetables.

This review examines the prevalence of three important pathogens, verocytotoxigenic Escherichia coli (VTEC), Salmonella enterica and Listeria monocytogenes, in cattle and beef from the farm to the final, ready-to-eat product. Factors affecting prevalence of pathogens in the beef chain, such as the season and cattle rearing method, are examined. Data from many key surveys are summarized in table form. The observed prevalence of pathogens in cattle and beef varies considerably from survey to survey. An indication of relative prevalence of pathogens at different stages can be obtained by calculating average prevalences observed over multiple surveys, weighted by sample number. Based on the data presented in the tables in this review, for E. coli O157 at selected processing stages the mean prevalences (and range of means from individual surveys) are faeces 6.2% (0.0–57%), hides 44% (7.3–76%), chilled carcasses 0.3% (0.0–0.5%), and raw beef products 1.2% (0.0–17%). For Salmonella the mean prevalence data are faeces 2.9% (0.0–5.5%), hides 60% (15–71%), chilled carcasses 1.3% (0.2–6.0%), and raw beef products 3.8% (0.0–7.5%). For L. monocytogenes the mean prevalence data are faeces 19% (4.8–29%), hides 12% (10–13%), and raw beef products 10% (1.6–24%). Seasonal variation was evident in many surveys, faecal prevalences of E. coli O157 and Salmonella generally being higher in the warmer months. The influence of animal type, animal age, feed and housing on pathogen carriage has also been examined. The significance of non-O157 serotypes of VTEC and their detection and classification are discussed.

This survey was launched after an unusual number of Salmonella Enteritidis outbreaks associated with the use of eggs in food service premises in England and Wales. Between November 2005 and December 2006, 9,528 eggs (1,588 pooled samples of 6 eggs) were collected from 1,567 food service premises in the United Kingdom, most of which (89%) were produced in the United Kingdom. Salmonella was isolated from 6 (0.38%) pools of eggs. Of these, 5 (0.31%) were Salmonella Enteritidis, which were further characterized to phage types (PTs): PT 4 (0.19%), PT 8 (0.06%), and PT 12 (0.06%). Salmonella Mbandaka was also isolated (0.06%). Salmonella was detected from five and one of pooled eggs samples that were produced in the United Kingdom and Germany, respectively; these were from different producers. The study showed evidence of poor egg storage and handling practices in food service premises, in that 55% did not store eggs under refrigerated conditions; 20.7% of eggs had expired "best before" dates or were in use after 3 weeks of lay, indicating poor stock rotation; and 37.1% pooled eggs not intended for immediate service. Eggs are a commonly consumed food that may occasionally be contaminated with Salmonella at different rates, according to their country of origin. The food service sector needs to be aware of this continuing hazard, receive appropriate food safety and hygiene training on storage and usage of raw shell eggs, adopt appropriate control measures, and follow advice provided by national food agencies in order to reduce the risk of infection.

A novel method for the extraction and purification of bacteriocins (small peptides with antimicrobial properties) from fermentation broths is described. Model solutions of nisin were prepared from Nisaplin®, a commercial whey-based powder containing about 2.5% nisin and sold as a food preservative. These model solutions and fermentation broths from a culture of nisin-producing Lactococcus lactis subsp lactis were cross-flow filtered and stirred with toluene to obtain a white suspension in the toluene layer, which was back extracted with 10 mmol dm−3 HCl. Yields of the order of 90% for a single stage extraction were obtained followed by similar yields on back extraction. Yields dropped with decreasing pH, going through a minimum at pH 2. In larger scale experiments (11 dm3) at pH 6, a gel layer was formed which, on centrifugation and drying, gave a white solid containing about 50% nisin, the remainder being water and salt. Further process development would almost certainly bring this figure closer to the small-scale value. The phase transfer technique was also applied to solutions containing variacin and carnocin (produced by Micrococcus varians and Carnobacterium piscicola, respectively). The mechanism of bacteriocin extraction probably involves concentration of the peptides, which are surface active, at the interface until their solubility is exceeded and they form reverse submicelles, which aggregate into reverse micelles to give a gel. © 2000 Society of Chemical Industry

The objective of this study was to determine whether chitosan (poly-β-1,4-glucosamine) and hydrolysates of chitosan can be used as novel preservatives in foods. Chitosan was hydrolyzed by using oxidative-reductive degradation, crude papaya latex, and lysozyme. Mild hydrolysis of chitosan resulted in improved microbial inactivation in saline and greater inhibition of growth of several spoilage yeasts in laboratory media, but highly degraded products of chitosan exhibited no antimicrobial activity. In pasteurized apple-elderflower juice stored at 7°C, addition of 0.3 g of chitosan per liter eliminated yeasts entirely for the duration of the experiment (13 days), while the total counts and the lactic acid bacterial counts increased at a slower rate than they increased in the control. Addition of 0.3 or 1.0 g of chitosan per kg had no effect on the microbial flora of houmous, a chickpea dip; in the presence of 5.0 g of chitosan per kg, bacterial growth but not yeast growth was substantially reduced compared with growth in control dip stored at 7°C for 6 days. Improved antimicrobial potency of chitosan hydrolysates like that observed in the saline and laboratory medium experiments was not observed in juice and dip experiments. We concluded that native chitosan has potential for use as a preservative in certain types of food but that the increase in antimicrobial activity that occurs following partial hydrolysis is too small to justify the extra processing involved.

The ability of chito-oligosaccharides (COS) to inhibit selected intestinal bacteria was investigated. COS at 2.5 mg ml(-1) had no significant effect on the adhesion of three strains of verotoxigenic Escherichia coli (VTEC), Lactobacillus pentosus, L. casei or L. gasseri to human HT29 cells in tissue culture. However, COS significantly inhibited adhesion of three strains of enteropathogenic E. coli (EPEC) to below 30% of the level of adhesion seen in the controls. Dose-response curves were constructed to further characterise the inhibition of EPEC strains to HT29 cells. (c) 2005 Elsevier Ltd. All rights reserved.

Aims To investigate the potential use of oregano essential oil as an antimicrobial agent in liquid soap for hand washing and for food contact surface cleaning. Methods and Results Oregano essential oil (O.E.O.) was emulsified in liquid detergent solution. This was challenge tested against a commercial antimicrobial soap in hand washing trials using natural flora. Soap with O.E.O. was as effective as the commercial antimicrobial soap at reducing aerobic plate count on the hands and more effective than plain soap with no additives. Cloths wetted with soap with O.E.O. were used to clean three different surfaces contaminated with four bacterial pathogens. For three of the four pathogens, the addition of 0·5% v/v O.E.O. to the soap solution enhanced cleaning performance and also reduced bacterial survival on the cloth after cleaning. Conclusions Oregano essential oil (0·5%) is effective as an antimicrobial additive to detergent solutions for hand washing and surface cleaning. Significance and Impact of Study This preliminary study has shown that oregano essential oil is a potential alternative to antimicrobials used in various detergents, such as chloroxylenol and triclosan, which can have adverse environmental and health effects. Further development could lead to a commercial product.

The effect of marination on the survival and growth of the pathogens Salmonella enterica and Listeria monocytogenes on beef pieces was investigated. Five marinades were used: soy sauce base marinade without (SB) or with lactic acid (SBLA), red wine base marinade without (WB) or with 0.5% v/v oregano essential oil (WBO), and sterile saline used as control (C). Inoculated fresh beef pieces were marinated for 18 h at 5 °C, removed from the marinade and subjected to storage trials at 5 °C and 15 °C. Heat inactivation studies were also performed on the isolates after exposure to the marinades to determine if marination affects heat resistance of the pathogens. The marinades with antimicrobials caused a significant decrease in viable count of the pathogens during marinations at 5 °C for 18 h of up to 2.1 and 3.4 log cfu cm(-2) for Salmonella and L. monocytogenes, respectively. Marinades without antimicrobials were less bactericidal resulting to reductions ranging from 0.3 to 0.4 and 1.3 to 2.0 log cfu cm(-2) for Salmonella and L. monocytogenes, respectively. Growth of L. monocytogenes was observed in the controls at both tested temperatures, while growth of Salmonella was observed in the controls stored at 15 °C. No growth of the pathogens was observed in any of the marinated samples at both temperature tested. No significant changes of heat resistance of the tested pathogens after exposure to the marinades were observed demonstrating the enhanced safety of the marinated beef product.

Fresh beef slices were marinated by immersion in marinades based on soy sauce without (SB) or with lactic acid (SBLA) or red wine base without (WB) or with 0.5% v/v oregano essential oil (WBO). For control samples (immersed in saline), a mean increase of 0.9log CFU/cm(2) in total viable counts (TVCs) occurred during the 24 h treatment. During marination with WB and SB, mean TVC decreased by 0.7 and 0.3log CFU/cm(2), respectively. The mean decrease in TVC for samples marinated in WBO or SBLA was 1.2log CFU/cm(2). Subsequent storage of beef resulted in a rapid increase of TVC in control samples, to >9.5log CFU/cm2 after 8 days at 5 degrees C or 3 days at 15 degrees C. Significant (P < 0.05) microbial growth occurred in marinated samples stored at 5 degrees C. During storage at 15 degrees C TVC increased in only WB samples but the final numbers of 5.9log CFU/cm(2) were significantly lower (P < 0.05) than the numbers in the control. Results similar to those for TVC were observed for Pseudomonas spp. All marinades also gave meat with significant lower TBARS values than the controls. There were no significant differences (P > 0.05) in the toughness of the marinated samples compared to the control, except for SBLA samples which had significantly higher (P < 0.05) shear force values. Marination with soy sauce or red wine marinades can evidently control microbial spoilage and oxidation of meat. (C) 2010 Elsevier Ltd. All rights reserved. Food Microbiology

The aim of the study was to investigate the ability of pectic oligosaccharides (POS) to inhibit adhesion of three strains of verotoxigenic Escherichia coli, three strains of enteropathogenic E. coli, and one nonclinical strain of Desulfovibrio desulfuricans to human intestinal epithelial cell cultures. Lactobacillus acidophilus and Lactobacillus gasseri were included for comparison. Attachment was determined in the human HT29 cell line by viable count of adherent bacteria. POS in buffer at pH 7.2 were antiadhesive at a dose of 2.5 mg ml(-1), reducing adhesion of enteropathogenic E. coil and verotoxigenic E. coli strains to less than 30% of control values. Concentrations resulting in 50% inhibition ranged from 0.15 to 0.46 mg ml(-1). L. acidophilus was not significantly affected, but adhesion of L. gasseri was reduced to 29% of the control value. POS reduced the adhesion of D. desulfuricans to 0.33% of the control value. POS also had a protective effect against E. coli verocytotoxins VT1 and VT2 at concentrations of 0.01 and 1 microg ml(-1), respectively.

Two studies of retail fresh, ripened and semi-hard cheeses made from raw, thermized or pasteurized milk were undertaken in the UK during 2004 and 2005 to determine the microbiological quality of these products. Using microbiological criteria in European Commission Recommendations 2004/24/EC and 2005/175/EC, 2% of both raw, thermized (37/1819 samples) and pasteurized (51/2618 samples) milk cheeses were of unsatisfactory quality. Raw or thermized milk cheeses were of unsatisfactory quality due to levels of Staphylococcus aureus at 10(4)cfu g(-1), Escherichia coli at 10(5)cfu g(-1), and/or Listeria monocytogenes at 10(2)cfu g(-1), whereas pasteurized milk cheeses were of unsatisfactory quality due to S. aureus at 10(3)cfu g(-1) and/or E. coli at 10(3)cfu g(-1). Salmonella was not detected in any samples. Cheeses were of unsatisfactory quality more frequently when sampled from premises rated as having little or no confidence in management and control systems, and stored/displayed at above 8 degrees C. Raw or thermized milk cheeses were also more likely to be of unsatisfactory quality when they were unripened types, and pasteurized milk cheeses when they were: semi-hard types; from specialist cheese shops or delicatessens; cut to order. These results emphasize the need for applying and maintaining good hygiene practices throughout the food chain to prevent contamination and/or bacterial growth. Labelling of cheeses with clear information on whether the cheese was prepared from raw milk also requires improvement.

Caseinoglycomacropeptide (CGMP) derived from kappa-casein was investigated for its ability to inhibit the adhesion of 3 strains of verotoxigenic Escherichia coli (VTEC) and 3 strains of enteropathogenic Escherichia coli (EPEC) to human HT29 tissue cell cultures. Effects on adhesion of Desulfovibrio desulfuricans, Lactobacillus pentosus, Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus gasseri were also investigated. Generally, CGMP exerted effective anti-adhesive properties at a dose of 2.5 mg/mL, albeit with a high degree of strain specificity. The CGMP reduced adhesion of VTEC strains to

The mode of antimicrobial action of chitosan (polymeric β-1,4-N-acetylglucosamine) on Gram-negative bacteria was studied with special emphasis on its ability to bind to and weaken the barrier function of the outer membrane (OM). Chitosan (250 ppm) at pH 5.3 induced significant uptake of the hydrophobic probe 1-N-phenylnaphthylamine (NPN) in Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium. The effect was reduced (E. coli, salmonellae) or abolished (P. aeruginosa) by MgCl2. No NPN uptake was observed during exposure of the salmonellae to chitosan at pH 7.2. Chitosan also sensitized P. aeruginosa and the salmonellae to the lytic effect of sodium dodecyl sulfate (SDS); such sensitization was not blocked by MgCl2 and was reversible by washing chitosan-treated cells prior to SDS exposure. Chemical and electrophoretic analyses of cell-free supernatants of chitosan-treated cell suspensions showed that interaction of chitosan with E. coli and the salmonellae involved no release of lipopolysaccharide (LPS) or other membrane lipids. However, chitosan rendered E. coli more sensitive to the inhibitory action of dyes and bile acids used in selective media. Highly cationic mutants of S. typhimurium were more resistant to chitosan than the parent strains. Electron microscopy showed that chitosan caused extensive cell surface alterations and covered the OM with vesicular structures. Chitosan thus appeared to bind to the outer membrane, explaining the loss of the barrier function. This property makes chitosan a potentially useful indirect antimicrobial for food protection.