Detection of Genetically Modified Soy in Doughs and Cookies

In many countries, including the European Union member states, Switzerland, Australia, New Zealand, and Japan, legislation has been set up for labeling of genetically modified organisms (GMOs) in food and feed products. To comply with these regulations, reliable detection methods are necessary. If the detection is based on DNA, a GMO analysis may contain several steps where qualitative and quantitative species-specific, GMO screening, GMO construct, and GMO line-specific polymerase chain reactions (PCRs) are used. A limit of detection (LOD) thereby defines to what extent a target molecule may be detected in a sample. In this study, cookies were made with variable levels of a soy sample containing 2 wt% Roundup Ready soy. For all PCRs described, detection limits based on dilution series and practical LODs were determined. The practical LODs are used to determine to what extent a GMO ingredient may be detected in a real food product. Results reveal that, due to the baking process, the overall DNA fragment length is reduced, rendering GMO analyses more difficult. Furthermore, Roundup Ready soy line-specific and real-time quantitative PCR are less sensitive than GMO screening PCRs, whereas just these PCRs are crucial in the decision-making process regarding the presence of GMOs in a food product. Moreover, high standard deviations and errors render the precise quantification of GMOs difficult.     

Expert judgement in a risk assessment model for Salmonella spp. in pork: The performance of different weighting schemes

A structured expert judgement study was carried out in order to obtain input parameters for a quantitative microbial risk assessment (QMRA) model. This model aimed to estimate the risk of human Salmonella infections associated with the consumption of minced pork meat. Judgements of 11 experts were used to derive subjective probability density functions (PDFs) to quantify the uncertainty on the model input parameters.The performance of experts as probability assessors was measured by the experts’ ability to correctly and precisely provide estimates for a set of seed variables (=variables from the experts’ area of expertise for which the true values were known to the analyst). Subsequently different weighting schemes or “decision makers” (DMs) were applied using Cooke's classical model in order to obtain combined PDFs as a weighted linear combination of the expert's individual PDFs.The aim of this study was to compare the performance of four DMs namely the equal weight DM (each expert's opinion received equal weight), the user weight DM (weights are determined by the expert's self-perceived level of expertise) and two performance-based DMs: the global weight DM and the item weight DM. Weights in the performance-based DMs were calculated based on the expert's calibration and information performance as measured on the set of seed variables.The item weight DM obtained the highest performance with a calibration score of 0.62 and an information score of 0.52, as compared to the other DMs. The weights of the performance-based DMs outperformed those of the best expert in the panel. The correlation between the scores for self-rating of expertise and the weights based on the experts’ performance on the calibration variables was low and not significant (r = 0.37, p = 0.13).The applied classical model provided a rational basis to use the combined distributions obtained by the item weight DM as input in the QMRA model since this DM yielded generally more informative distributions for the variables of interest than those obtained by the equal weight and user weight DM. Attention should be paid to find adequate and relevant seed variables, since this is important for the validation of the results of the weighting scheme.     

Multiple typing for the epidemiological study of contamination of broilers with thermotolerant Campylobacter

This study aims to investigate the genetic diversity of thermotolerant Campylobacter in commercial broiler flocks and in the environment of broiler farms in Belgium. Seven out of 18 investigated flocks became colonized during rearing. Fluorescent amplified fragment length polymorphism (FAFLP), pulsed field gel electrophoresis (PFGE), restriction fragment length polymorphism of the flagellin A gene (flaA-RFLP) and antimicrobial resistance profile (ARP) were used for typing of the isolates. By the combination of FAFLP and PFGE, 22 Campylobacter genotypes could be distinguished. Colonization was almost exclusively with Campylobacter jejuni and unique genotypes were found in each flock. Multiple genotypes were detected in the broilers of 3 flocks, either simultaneously or successively. In 5 flocks, strains that were resistant to at least one antibiotic (mostly tetracycline) were found. The presence of other broiler houses on the farm did not result in a higher probability of colonization. The nipple water was contaminated with the same genotype as the broilers, illustrating its importance for transmission of Campylobacter. The same genotype was detected in a water puddle and in the broiler flock during rearing in 3 flocks. Once, the same genotype was isolated from the ditch water shortly before it was detected in the broilers.     

Fusarium head blight (FHB) in Flanders: population diversity, inter-species associations and DON contamination in commercial winter wheat varieties

The presence of Fusarium spp. causing Fusarium head blight (FHB) of wheat was studied in Flanders (Belgium) in 2007 and 2008. Symptoms, deoxynivalenol content (DON), Fusarium spp. and trichothecene chemotypes were determined at seven locations on different commercial wheat varieties. Overall, significant differences in disease pressure between locations and varieties were observed within 1 year. In addition, we were able to detect consistent and significant resistance differences among the common varieties both under high disease pressure (2007) and low disease pressure (2008). The accumulation of DON was not related to the presence of F. graminearum but showed a clear correlation with rainfall during and after the period of anthesis. During the two-year survey, characterisation of 756 Fusarium samples by species-specific PCR designated F. poae and F. graminearum as the predominant species in Flanders. Furthermore, most of the ears were colonised by multiple FHB pathogens in 2007 whereas the Fusarium population was less complex in 2008. Log-linear analysis of these multiple (two- and three-way) species interactions revealed a clear correlation between F. poae and several pathogens of the FHB disease complex. Finally, chemotype analysis showed that F. culmorum and F. graminearum were respectively of the NIV chemotype and DON chemotype. 3-ADON and 15-ADON chemotypes occurred in more or less equal amounts within the F. graminearum population both in 2007 and 2008. The congruence of these results with observations throughout Europe are discussed.     

Campylobacter control in poultry by current intervention measures ineffective: urgent need for intensified fundamental research

Campylobacter-contaminated poultry meat is an important source of foodborne gastroenteritis and poses a serious health burden in industrialized countries. Broiler chickens are commonly regarded as a natural host for this pathogen and infected birds carry a very high Campylobacter load in their gastrointestinal tract, especially the ceca. This results in contaminated carcasses during processing. While hygienic measures at the farm and control measures during carcass processing can have some effect on the reduction of Campylobacter numbers on the retail product, intervention at the farm level by reducing colonization of the ceca should be taken into account in the overall control policy. This review gives an up-to-date overview of suggested on-farm control measures to reduce the prevalence and colonization of Campylobacter in poultry.     

Influence of amylovoran production on virulence of Erwinia amylovora and a different amylovoran structure in E. amylovora isolates from Rubus

The amylovoran structures of five Erwinia amylovora isolates from Malaceae sp. and four isolates from Rubus sp. host plants were fully established, mainly by NMR. The structural data on one E. amylovora isolate from a Malaceae sp. host, which had been previously suggested by mass and NMR (Nimtz et al., 1996), were completed. E. amylovora strains infective on Malaceae sp. host plants had an amylovoran composed of pentasaccharide and 30–40% hexasaccharide repeating-substructures, whereas amylovoran from E. amylovora isolates from Rubus sp. host plants had only the pentasaccharide substructures. On the other hand, the exopolysaccharide (EPS) production differed in wild-type E. amylovora strains. Data on in vitro amylovoran production per cell could account for the differences in aggressiveness found in E. amylovora strains, as deduced from a pilot test with highly, moderately, and weakly aggressive strains. This correlation was confirmed with several other wild-type E. amylovora strains from different origin.     

Fla-DGGE analysis of Campylobacter jejuni and Campylobacter coli in cecal samples of broilers without cultivation

In a commercial broiler flock during rearing multiple genotypes of Campylobacter jejuni may be present as well as in gastrointestinal tracts of individual birds. The aim of this study was to optimize and apply a denaturing gradient gel electrophoresis assay of the flagellin gene (fla-DGGE) for analysis of C. jejuni and Campylobacter coli in cecal samples of broilers without prior cultivation. One C. coli and 21 C. jejuni strains isolated from broiler flocks, of which 14 typed as unique by restriction fragment length polymorphism of flaA and two undefined strains, were clustered into 9 groups when applying fla-DGGE. Spiking of cecal samples revealed that fla-DGGE is able to detect at least 4.55-5.96logCFUCampylobacter/mlcecal material. The presence of 3 strains spiked in cecal material was demonstrated by fla-DGGE as the corresponding bands were visible on the DGGE gel. Naturally contaminated cecal samples were shown to contain different types of C. jejuni and C. coli. Fla-DGGE has some potential as a cultivation-independent fast primary subtyping method for C. jejuni and C. coli in cecal samples of broilers.     

Eggshell penetration of hen's eggs by Salmonella enterica serovar Enteritidis upon various storage conditions

1. The survival and penetration of Salmonella enterica serovar Enteritidis (SE) inoculated on the eggshell was examined upon storage for up to 20 d at real-life conditions (15 to 25 degrees C and 45 to 75% relative humidity (RH)). 2. Penetration was assessed by emptying the egg contents and filling the eggs with a selective medium that allowed visualising Salmonella growth on the inside of the shell and membrane complex. 3. The study of survival on the eggshells was based on viable counts and showed that numbers of surviving organisms decreased over time. Survival was inversely related to storage temperature and RH. Although the average counts decreased over time, a limited proportion of shells carried high numbers of SE at all storage conditions. 4. Penetration spots were observed earlier using an increased storage temperature due to increased growth rates of SE on the agar. After 20 d of storage a similar percentage (c. 44.7%) of eggshells became penetrated, irrespective of the storage conditions tested in this study. 5. The higher the Salmonella shell contamination at the end of storage, the higher the probability that the eggshell was penetrated. Salmonella shell counts exceeding 4 log cfu yielded more than a 90% probability of eggshell penetration occurring.     

Colonization factors of Campylobacter jejuni in the chicken gut

ABSTRACT: Campylobacter contaminated broiler chicken meat is an important source of foodborne gastroenteritis and poses a serious health burden in industrialized countries. Broiler chickens are commonly regarded as a natural host for this zoonotic pathogen and infected birds carry a very high C. jejuni load in their gastrointestinal tract, especially the ceca. This eventually results in contaminated carcasses during processing. Current intervention methods fail to reduce the colonization of broiler chicks by C. jejuni due to an incomplete understanding on the interaction between C. jejuni and its avian host. Clearly, C. jejuni developed several survival and colonization mechanisms which are responsible for its highly adapted nature to the chicken host. But how these mechanisms interact with one another, leading to persistent, high-level cecal colonization remains largely obscure. A plethora of mutagenesis studies in the past few years resulted in the identification of several of the genes and proteins of C. jejuni involved in different aspects of the cellular response of this bacterium in the chicken gut. In this review, a thorough, up-to-date overview will be given of the survival mechanisms and colonization factors of C. jejuni identified to date. These factors may contribute to our understanding on how C. jejuni survival and colonization in chicks is mediated, as well as provide potential targets for effective subunit vaccine development.     

Effect of spray application technique on spray deposition in greenhouse strawberries and tomatoes

BACKGROUND: Increasingly, Flemish greenhouse growers are using spray booms instead of spray guns to apply plant protection products. Although the advantages of spray booms are well known, growers still have many questions concerning nozzle choice and settings. Spray deposition using a vertical spray boom in tomatoes and strawberries was compared with reference spray equipment. Five different settings of nozzle type, size and pressure were tested with the spray boom. RESULTS: In general, the standard vertical spray boom performed better than the reference spray equipment in strawberries (spray gun) and in tomatoes (air‐assisted sprayer). Nozzle type and settings significantly affected spray deposition and crop penetration. Highest overall deposits in strawberries were achieved using air‐inclusion or extended‐range nozzles. In tomatoes, the extended‐range nozzles and the twin air‐inclusion nozzles performed best. Using smaller‐size extended‐range nozzles above the recommended pressure range resulted in lower deposits, especially inside the crop canopy. CONCLUSIONS: The use of a vertical spray boom is a promising technique for applying plant protection products in a safe and efficient way in tomatoes and strawberries, and nozzle choice and setting should be carefully considered. Copyright © 2009 Society of Chemical Industry