Qualité microbiologique des fromages artisanaux fabriqués au lait cru en Région wallonne

Microbiological quality of craft raw milk cheeses produced in Wallonia. The main objective of this study was to evaluatethe bacteriological quality of raw milk cheeses produced in the southern part of Belgium (Wallonia) and to compare withsamples coming from other European countries. Results from bacteriological analyses of 153 cheese samples have beencompared with regard to food microbial standards (92/46 EC Directive). It can be concluded from this work that 69% of thesamples may be considered as acceptable, while 31% showed coliforms and Staplylococcus aureus counts exceeding thestandard values. As far as pathogens were concerned, 0.7% and 7.2% of the samples have were found unsatifactory with thecriteria related to Salmonella and Listeria monocytogenes, respectively. Enterobacteriaceae contamination has also beenevaluated and demonstrated an average log count of about 3.78 cfu/g. Cheeses produced from ewe milk showed anoutstanding microbiological quality since all samples turned out to be acceptable regarding the S. aureus counts and devoidof Salmonella and L. monocytogenes contamination. Although no seasonal effect on the bacteriological quality could beobserved, the microbial quality decreased after the production stage, i.e. mainly during the storage and the distribution.Cheese made by small producers seems to be better than those originating from industrial enterprises. By comparing theseresults with those obtained on cheese samples produced in some other European countries, it appears that the mean qualitylevel of Walloon raw milk cheeses is quite satifactory

[Food microbiology: proficiency testing scheme on a naturally contaminated fresh refrigerated food.]

The major objective of the study is to assess the performance of a proficiency testing scheme of a fresh refrigerated dairy product and to compare it with those applied currently in food microbiology. The accuracy is evaluated by using the repeatability and reproducibility standard deviations (respectively referred as s(r) and s(R)). For total mesophilic bacteria, with a mean Log count of around 8 bacteria per g, s(r) was equal to 0.15 and s(R) equal to 0.32. For total and fecal coliforms, these Values were respectively s(r) = 0.19, s(R) = 0.34, and s(r) = 0.20, s(R) = 0,50, at mean Log count of about 3.76 bacteria per g. For Staphylococcus aureus at a contamination level ranging between 1.5 and 4 Log count bacteria per g, these values were s(r) = 0.54 and s(R) = 1.33. Because our samples were originally Salmonella free, spiked samples were used. The sensitivity rate of the method is 95.8 % and the specificity rate 99.1 %. In the course of the present study, a significant progressive improvement of performance among laboratories was observed

[Rapid enumeration of bacteria in foods using Direct Epifluorescent Filter Technique.]

The aim of this study was to test the feasibility of a method designed for the rapid counting of bacteria in various kinds of foods i.e. the Direct Epifluorescent Filter Technique (DEFT). With frozen vegetables, total bacteria count found in 103 samples (n = 103) is significantly correlated (r = 0.87) with the standard method (Plate count agar - PCA); with raw meat (n = 14), even if the DEFT seems to overestimate the total bacteria populations, the correlation with PCA is higher (r = 0.99). However, for this last kind of food, an extraction of fat is necessary. When poultry products are examined, the correlation obtained with neck skin samples is unsatisfactory (r = 0.42). As far as the enumeration of more specific bacteria populations is concerned, e.g. the Enterobacteriaceae in frozen spinach (n = 28), a poor correlation is observed with the standard procedure (r = 0.57). However, better results are obtained with the enumeration of Staphylococcus aureus in raw meat (r = 0.8 to 0.95, n = 17). Good agreement is obtained between visual counting (r = 0.95) and semi-automated image analyser counting

Usefulness of cellular fatty acid patterns for identification and pathogenicity of Yersinia species

The cellular fatty acid composition of common non-pathogenic and pathogenic Yersinia strains was determined by gas-liquid chromatography. This study included most of the species of the genus Yersinia, with the exception of Y. pestis. All species possess a rather similar fatty acid pattern characterized by some major compounds, namely C12:0, 14:0, 3-OH-14:0, 16:0, 16,1 omega 9cis, 17:0 cyclic and 18:1 omega 9trans acids, as in other Enterobacteriaceae. By using the overlap coefficient of Bousfield, the similarity value enabled us to identify easily the Yersinia genus of an unknown strain. In the same way, the pathogenicity of strains of Yersinia enterocolitica and related species can be determined by the C12:0/C16:0 and C14:0/C16:0 ratios

Two-Step Nanoscale Approach for Well-Defined Complex Alkanethiol Films on Au Surfaces

Controlling the molecular organization of organic self-assembled monolayers (SAM) is of utmost importance in nanotechnology, molecular electronics, and surface science. Here we propose two well-differentiated approaches, double printing based on microcontact printing (μ-cp) and molecular backfilling adsorption, to produce complex alkanethiol films. The resulting films on model Au surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Double printing alkanethiols results in clear coexisting regions where no molecular displacement is observed, highlighting the slow diffusion rates of long alkanethiols and large attractive interaction between long alkyl chains. Exposing a single-print μ-cp Au substrate to an additional alkanethiol solution yields the formation of differently ordered domain boundaries with different thickness and micrometer lateral size. The high order is a result of enhanced molecular mobility and restructuring during solution backfilling. The formed molecular assemblies constitute an excellent testing ground for nanoscale phenomena that strongly depend on the nanoscale geometrical and chemical features of the surface such as designed functionality or corrosion initiation and inhibition.SCOPUS: ar.jinfo:eu-repo/semantics/publishe