Comparison of enterococcal populations in animals, humans, and the environment--a European study

The objectives of the present study were to generate knowledge of enterococcal populations in the food chain, by studying the population structure (in measures of abundance and diversity) among enterococci in different geographical regions and in different parts of the food chain, as well as the similarities between different enterococcal populations. Altogether, 2868 samples were collected from humans (healthy and hospitalised individuals and clinical isolates), animals (slaughterhouse carcasses and farm animals), and the environment (pig farms, sewage, and surface water) in four European countries-Sweden, Denmark, UK, and Spain. The samples were characterised with regard to presence and numbers of enterococci, and eight (for faecal samples) or 24 (for environmental samples) isolates per sample were phenotyped and preliminarily identified with the PhP-RF system. In total, more than 20,000 isolates were typed. A majority of the samples (77%) showed the presence of presumed enterococci. The diversities of enterococci in environmental samples were generally high, and also faecal samples normally showed presence of more than one enterococcal strain. The most common species found were Enterococcus faecium (33%), E. faecalis (29%), and E. hirae (24%), but different enterococcal populations differed in their species distribution. Clinical isolates, hospitalised patients, and hospital sewage in Sweden showed a clear dominance of E. faecalis (80%, 57%, and 54%, respectively) whereas healthy individuals and urban sewage contained less E. faecalis (39% and 40%, respectively). The species distribution among isolates from slaughterhouses varied between animal species and also between countries, but E. faecalis seemed to be mainly associated with broiler, and E. hirae with cattle and pigs. The results from the study have indicated a simplified method to study the diversity of bacterial populations. Instead of collecting many samples and analysing one or a few isolates per sample, it is possible to collect fewer samples and analyse several isolates per sample. Both approaches yielded similar information on the diversity of the populations. Another useful information was that since samples from hospital sewage, urban sewage, and manure contained enterococcal populations that reflected those in faecal samples of hospitalised patients, healthy humans, and animals, respectively, such samples may be used as pooled faecal samples and may replace cumbersome samplings from many individuals.     

Geographical differentiation of white wines from three subzones of the designation of origin Valencia

The chemical composition of 50 Spanish white wines, 1998 and 1999 vintages, from three subzones of the Designation of Origin Valencia (Alto Turia, Clariano and Valentino), was studied. The 35 components analysed were grouped according to the conventional parameters, alcohols and polyols, and esters. Discriminant analysis was applied to each one of these groups and to each one of the vintages; this did not allow us to correctly classify these wines in their corresponding subzone. To carry out a more exact classification of the studied wines in their corresponding subzone, it was necessary to carry out a discriminant analysis with the 35 parameters and the 50 wines (98% well classified). A stepwise discriminant analysis was used to eliminate the less significant variables. The discriminant analysis was also carried out using only 18 variables and this also led to successful results: 96% of the samples were correctly classified. Using only four parameters, total acidity, ashes (conventional parameters), pentanol (alcohols) and diethyl succinate (esters), we managed to successfully classify 84% of the wines studied into their corresponding subzone.     

Influence of thermal treatment on the flow of starch-based food emulsions

Modified starch from maize has been investigated under different pasting conditions. The effect of the time and temperature of gelification, which is known to be of particular importance in the functional properties of starch in industrial processes, has been specifically investigated. The main objective was to evaluate the effect of starch thermal treatment on the rheological properties of a salad dressing, taken as a model of starch-based sauces, and prepared with the same starches in similar pasting conditions. The results obtained are explained on the basis of the relationships among flow behaviour, droplet size distribution and characteristics of the continuous phase.The emulsions became more viscous with increasing starch heating time. The emulsions exhibited a complex viscous behaviour that was fitted to the Carreau model. Flow behaviours of emulsions and starch gels have been compared. A unique master curve has been obtained for all emulsions and gels studied, which depends only on the starch heating time. In addition, changes in microstructure and viscosity, during gelification of the starch dispersion, have been analysed by combining rheological measurements with optical observations and digital image processing techniques.     

Diffusion-based model to predict the conservation of gratings recorded in poly(vinyl alcohol)-acrylamide photopolymer

Photopolymers are interesting materials for use in recording information in holography. We study the holographic behavior and stability of volume holograms recorded in poly(vinyl alcohol)--acrylamide photopolymers with and without a cross linker. Using a first-harmonic diffusion model, we analyze the residual monomer that remains when volume diffraction gratings are recorded in photopolymer materials. The importance of this residual monomer to the stability of the gratings is evaluated.     

Cognitive flexibility and adaptability to environmental changes in dynamic complex problem-solving tasks

People who show good performance in dynamic complex problem-solving tasks can also make errors. Theories of human error fail to fully explain when and why good performers err. Some theories would predict that these errors are to some extent the consequence of the difficulties that people have in adapting to new and unexpected environmental conditions. However, such theories cannot explain why some new conditions lead to error, while others do not. There are also some theories that defend the notion that good performers are more cognitively flexible and better able to adapt to new environmental conditions. However, the fact is that they sometimes make errors when they face those new conditions. This paper describes one experiment and a research methodology designed to test the hypothesis that when people use a problem-solving strategy, their performance is only affected by those conditions which are relevant to that particular strategy. This hypothesis is derived from theories that explain human performance based on the interaction between cognitive mechanisms and environment.     

The Microbiota and the Gut–Brain Axis in Controlling Food Intake and Energy Homeostasis

Obesity currently represents a major societal and health challenge worldwide. Its prevalence has reached epidemic proportions and trends continue to rise, reflecting the need for more effective preventive measures. Hypothalamic circuits that control energy homeostasis in response to food intake are interesting targets for body-weight management, for example, through interventions that reinforce the gut-to-brain nutrient signalling, whose malfunction contributes to obesity. Gut microbiota–diet interactions might interfere in nutrient sensing and signalling from the gut to the brain, where the information is processed to control energy homeostasis. This gut microbiota–brain crosstalk is mediated by metabolites, mainly short chain fatty acids, secondary bile acids or amino acids-derived metabolites and subcellular bacterial components. These activate gut–endocrine and/or neural-mediated pathways or pass to systemic circulation and then reach the brain. Feeding time and dietary composition are the main drivers of the gut microbiota structure and function. Therefore, aberrant feeding patterns or unhealthy diets might alter gut microbiota–diet interactions and modify nutrient availability and/or microbial ligands transmitting information from the gut to the brain in response to food intake, thus impairing energy homeostasis. Herein, we update the scientific evidence supporting that gut microbiota is a source of novel dietary and non-dietary biological products that may beneficially regulate gut-to-brain communication and, thus, improve metabolic health. Additionally, we evaluate how the feeding time and dietary composition modulate the gut microbiota and, thereby, the intraluminal availability of these biological products with potential effects on energy homeostasis. The review also identifies knowledge gaps and the advances required to clinically apply microbiome-based strategies to improve the gut–brain axis function and, thus, combat obesity.     

Efficacy of neutral electrolyzed water (NEW) for reducing microbial contamination on minimally-processed vegetables

Consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. Sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. Neutral electrolyzed water (NEW) is a novel disinfection system that could represent an alternative to sodium hypochlorite. The aim of the study was to determine whether NEW could replace sodium hypochlorite in the fresh-cut produce industry. The effects of NEW, applied in different concentrations, at different treatment temperatures and for different times, in the reduction of the foodborne pathogens Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 and against the spoilage bacterium Erwinia carotovora were tested in lettuce. Lettuce was artificially inoculated by dipping it in a suspension of the studied pathogens at 10(8), 10(7) or 10(5) cfu ml(-1), depending on the assay. The NEW treatment was always compared with washing with deionized water and with a standard hypochlorite treatment. The effect of inoculum size was also studied. Finally, the effect of NEW on the indigenous microbiota of different packaged fresh-cut products was also determined. The bactericidal activity of diluted NEW (containing approximately 50 ppm of free chlorine, pH 8.60) against E. coli O157:H7, Salmonella, L. innocua and E. carotovora on lettuce was similar to that of chlorinated water (120 ppm of free chlorine) with reductions of 1-2 log units. There were generally no significant differences when treating lettuce with NEW for 1 and 3 min. Neither inoculation dose (10(7) or 10(5) cfu ml(-1)) influenced the bacterial reduction achieved. Treating fresh-cut lettuce, carrot, endive, corn salad and 'Four seasons' salad with NEW 1:5 (containing about 50 ppm of free chlorine) was equally effective as applying chlorinated water at 120 ppm. Microbial reduction depended on the vegetable tested: NEW and sodium hypochlorite treatments were more effective on carrot and endive than on iceberg lettuce, 'Four seasons' salad and corn salad. The reductions of indigenous microbiota were smaller than those obtained with the artificially inoculated bacteria tested (0.5-1.2 log reduction). NEW seems to be a promising disinfection method as it would allow to reduce the amount of free chlorine used for the disinfection of fresh-cut produce by the food industry, as the same microbial reduction as sodium hypochlorite is obtained. This would constitute a safer, 'in situ', and easier to handle way of ensuring food safety.     

Antioxidant Bioactive Compounds in Selected Industrial Processing and Fresh Consumption Tomato Cultivars

Four selected fresh consumption tomato varieties, harvested at different ripening stages (green, breaker, pink, red) and five industrial processing tomato varieties, harvested at red ripe stage, were analysed for lycopene and its isomers, β-carotene, total and individual phenolics, vitamin C and hydrophilic antioxidant activity. Tomato variety and ripening stage significantly affected carotenoids, total phenolic compounds and hydrophilic antioxidant activity when fresh consumption tomatoes were compared. The average of total lycopene content at the different ripening stages was 0.63, 12.20, 26.76 and 116.66 mg/kg of fresh weight (FW). Vitamin C ranged from 2.79 (breaker Cherry Pera) to 297.62 (red Cherry Pera) mg/kg FW. In green and breaker tomatoes, a positive correlation of hydrophilic antioxidant activity with vitamin C and chlorogenic acid was observed. However, in industrial tomato varieties (red ripe stage) and fresh consumption varieties harvested at pink and red stages, hydrophilic antioxidant activity was correlated with total phenolics and rutin. Tomato varieties for industrial processing did not show significant differences in total phenolic compounds and lycopene content. Lycopene ranged from 83.17 to 97.60 mg/kg FW, while total phenolic compounds varied between 257.91 and 284.13 mg/kg FW. Chlorogenic acid and rutin were the most abundant individual phenolics found in all the samples studied. Moreover, the content of total phenolics was always significantly correlated with the content of rutin. The amounts of all individual phenolics were affected by variety, with the exception of ferulic acid. Generally, these individual phenolics were more abundant in green and intermediate ripening stages, decreasing in full red tomatoes.