Pre-harvest Samples Research Articles

Aflatoxin B1 in senna pods from field to storage in Tamil Nadu, India

ABSTRACT Senna, a medicinal herb, is highly susceptible to aflatoxin contamination, which often limits the export value of the final products due to the regulatory limits of importing countries. Presence of aflatoxin B1 (AFB1) was investigated in 229 senna pod samples at various stages from field to storage over three years. Higher incidence of AFB1 was revealed during the late harvest stage with a mean level of 52.4 µg/kg and a range of LOD-206 µg/kg. Out of 48 late harvest samples, 37 exceeded the AFFB1 limit of 2 µg/kg. In contrast, the majority of preharvest samples showed lower levels of AFB1 (1.0 µg/kg). During drying, increase in the mean AFB1 level to 4 µg/kg was observed and it could further increase to 18.1 μg/kg in storage. These results highlight the status of aflatoxin contamination in senna pods and emphasise the importance of implementing good agricultural practices in senna cultivation to mitigate AFB1 contamination.

Exploring the interplay between the core microbiota, physicochemical factors, agrobiochemical cycles in the soil of the historic tokaj mád wine region.

A Hungarian survey of Tokaj-Mád vineyards was conducted. Shotgun metabarcoding was applied to decipher the microbial-terroir. The results of 60 soil samples showed that there were three dominant fungal phyla, Ascomycota 66.36% ± 15.26%, Basidiomycota 18.78% ± 14.90%, Mucoromycota 11.89% ± 8.99%, representing 97% of operational taxonomic units (OTUs). Mutual interactions between microbiota diversity and soil physicochemical parameters were revealed. Principal component analysis showed descriptive clustering patterns of microbial taxonomy and resistance gene profiles in the case of the four historic vineyards (Szent Tamás, Király, Betsek, Nyúlászó). Linear discriminant analysis effect size was performed, revealing pronounced shifts in community taxonomy based on soil physicochemical properties. Twelve clades exhibited the most significant shifts (LDA > 4.0), including the phyla Verrucomicrobia, Bacteroidetes, Chloroflexi, and Rokubacteria, the classes Acidobacteria, Deltaproteobacteria, Gemmatimonadetes, and Betaproteobacteria, the order Sphingomonadales, Hypomicrobiales, as well as the family Sphingomonadaceae and the genus Sphingomonas. Three out of the four historic vineyards exhibited the highest occurrences of the bacterial genus Bradyrhizobium, known for its positive influence on plant development and physiology through the secretion of steroid phytohormones. During ripening, the taxonomical composition of the soil fungal microbiota clustered into distinct groups depending on altitude, differences that were not reflected in bacteriomes. Network analyses were performed to unravel changes in fungal interactiomes when comparing postveraison and preharvest samples. In addition to the arbuscular mycorrhiza Glomeraceae, the families Mycosphaerellacae and Rhyzopodaceae and the class Agaricomycetes were found to have important roles in maintaining soil microbial community resilience. Functional metagenomics showed that the soil Na content stimulated several of the microbiota-related agrobiogeochemical cycles, such as nitrogen and sulphur metabolism; steroid, bisphenol, toluene, dioxin and atrazine degradation and the synthesis of folate.

Predicting foodborne pathogens and probiotics taxa within poultry-related microbiomes using a machine learning approach

BackgroundMicrobiomes that can serve as an indicator of gut, intestinal, and general health of humans and animals are largely influenced by food consumed and contaminant bioagents. Microbiome studies usually focus on estimating the alpha (within sample) and beta (similarity/dissimilarity among samples) diversities. This study took a combinatorial approach and applied machine learning to microbiome data to predict the presence of disease-causing pathogens and their association with known/potential probiotic taxa. Probiotics are beneficial living microorganisms capable of improving the host organism’s digestive system, immune function and ultimately overall health. Here, 16 S rRNA gene high-throughput Illumina sequencing of temporal pre-harvest (feces, soil) samples of 42 pastured poultry flocks (poultry in this entire work solely refers to chickens) from southeastern U.S. farms was used to generate the relative abundance of operational taxonomic units (OTUs) as machine learning input. Unique genera from the OTUs were used as predictors of the prevalence of foodborne pathogens (Salmonella, Campylobacter and Listeria) at different stages of poultry growth (START (2–4 weeks old), MID (5–7 weeks old), END (8–11 weeks old)), association with farm management practices and physicochemical properties.ResultWhile we did not see any significant associations between known probiotics and Salmonella or Listeria, we observed significant negative correlations between known probiotics (Bacillus and Clostridium) and Campylobacter at the mid-time point of sample collection. Our data indicates a negative correlation between potential probiotics and Campylobacter at both early and end-time points of sample collection. Furthermore, our model prediction shows that changes in farm operations such as how often the houses are moved on the pasture, age at which chickens are introduced to the pasture, diet composition and presence of other animals on the farm could favorably increase the abundance and activity of probiotics that could reduce Campylobacter prevalence.ConclusionIntegration of microbiome data with farm management practices using machine learning provided insights on how to reduce Campylobacter prevalence and transmission along the farm-to-fork continuum. Altering management practices to support proliferation of beneficial probiotics to reduce pathogen prevalence identified here could constitute a complementary method to the existing but ineffective interventions such as vaccination and bacteriophage cocktails usage. Study findings also corroborate the presence of bacterial genera such as Caloramator, DA101, Parabacteroides and Faecalibacterium as potential probiotics.

Preharvest Environmental and Management Drivers of Multidrug Resistance in Major Bacterial Zoonotic Pathogens in Pastured Poultry Flocks.

Due to nutritional benefits and perceived humane ways of treating the animals, the demand for antibiotic-free pastured poultry chicken has continued to be steadily rise. Despite the non-usage of antibiotics in pastured poultry broiler production, antibiotic resistance (AR) is reported in zoonotic poultry pathogens. However, factors that drive multidrug resistance (MDR) in pastured poultry are not well understood. In this study, we used machine learning and deep learning approaches to predict farm management practices and physicochemical properties of feces and soil that drive MDR in zoonotic poultry pathogens. Antibiotic use in agroecosystems is known to contribute to resistance. Evaluation of the development of resistance in environments that are free of antibiotics such as the all-natural, antibiotic-free, pastured poultry production systems described here is critical to understand the background AR in the absence of any selection pressure, i.e., basal levels of resistance. We analyzed 1635 preharvest (feces and soil) samples collected from forty-two pastured poultry flocks and eleven farms in the Southeastern United States. CDC National Antimicrobial Resistance Monitoring System guidelines were used to determine antimicrobial/multidrug resistance profiles of Salmonella, Listeria, and Campylobacter. A combination of two traditional machine learning (RandomForest and XGBoost) and three deep learning (Multi-layer Perceptron, Generative Adversarial Network, and Auto-Encoder) approaches identified critical farm management practices and environmental variables that drive multidrug resistance in poultry pathogens in broiler production systems that represents background resistance. This study enumerates management practices that contribute to AR and makes recommendations to potentially mitigate multidrug resistance and the prevalence of Salmonella and Listeria in pastured poultry.

Hematopoietic progenitor cell counting can optimize peripheral blood stem cell apheresis process.

Monitoring of stem cell concentration in transplantation settings is crucial to determine the optimal time of apheresis and is currently based on enumeration of CD34+ cells by flow cytometry. No surrogate marker has replaced CD34+ cell enumeration to date. The aim of this study was the evaluation of the hematopoietic progenitor cell (HPC) parameter of the Sysmex XN-1000 analyzer in terms of optimizing the peripheral blood stem cell apheresis process. Results of flow cytometric CD34+ cell and Sysmex HPC count were compared in 208 preharvest samples and 139 apheresis products. HPC and CD34+ cell counts showed significant differences in the multiple myeloma (MM) group. The correlation between preharvest HPC and CD34+ cell counts was good in the MM group (rho=.613) and strong in the lymphoma group (rho=.802), allogeneic donors (rho=.923), and other group of samples (rho=.816). The HPC positive cutoff demonstrating 100% specificity and positive predictive value for MM patients was high for ≥20/μL and ≥10/μL CD34+ cell counts, and therefore of limited value. The HPC negative cutoff demonstrating 100% sensitivity and negative predictive value was approximately <4/μL, irrespective of diagnosis. Based on proposed HPC positive cutoffs (≥31/μL in the lymphoma group and ≥11/μL in the other group of samples), routine HPC enumeration could improve the workflow by replacing CD34+ cell counting in allogeneic donors as well as non-MM patients. Furthermore, based on proposed HPC negative cutoff (<4/μL), CD34+ cell counting could be fully omitted in donors and patients that are not adequately mobilized.

Postharvest-induced microbiota remodeling increases fungal diversity in the phyllosphere mycobiota of broccoli florets

Fresh vegetables harbor numerous microbial populations in their phyllosphere. The phyllosphere microbiota is important not only for enhancing crop production, but also maintaining the quality and safety of fresh vegetables. However, studies of fungal communities on fresh vegetables are lacking, and very little is known about changes to fungal communities after harvest. This study explored the phyllosphere mycobiota of broccoli florets collected from 14 farms (n = 42, preharvest) and 10 retail stores (n = 40, postharvest) by culturing and amplicon sequencing of an internal transcribed spacer region. Core genera were identified that were specific to the broccoli phyllosphere. Fungal populations exceeded bacterial populations in both total abundance and biodiversity, and fungal communities differed much more between preharvest and postharvest samples than bacterial communities. The fungal variance explained by postharvest (25.4 %) was larger than the variance by farming region (10.9 %) or practice (10.9 %), but the bacterial variance by postharvest (3.5 %) was lower than that by farming region (19.5 %) or practice (9.5 %). Both species richness and evenness were significantly higher in postharvest samples, and the Ascomycota-to-Basidiomycota ratio was significantly lower in postharvest samples than in preharvest samples. Microbial association network analysis illustrated that preharvest interspecies interactions involving Purpureocillium and Cystofilobasidium were replaced with interactions involving Sporobolomyces, Papiliotrema, and Bulleromyces in postharvest samples, resulting in a decrease of network robustness, as corroborated by functional changes and enrichment of a postharvest pathogen. Overall, the fungal community is an important component of postharvest microbiome in the phyllosphere of fresh vegetables that has large potential impacts on fresh produce storage and spoilage.

Aspergillus species and aflatoxin contamination in pepper (Capsicum annuum L.) in West Gojjam, Ethiopia

Pepper (Capsicum annuum L.) is an important spice and source of income for smallholder producers in Ethiopia. Since the larger proportion is for the market, it takes a significant share of the national income from export commodity. However, often the product was rejected by some of the European Union markets due to the maximum aflatoxin level accumulations beyond their acceptable limits. So, the present study was carried out to highlight the importance of Aspergillus species invasion in pepper, and levels of aflatoxin contamination at maturity in the field (pod form), farmers' storage and local market (powder form)in West Gojjam, Ethiopia. A total of 135 pepper samples were collected from three districts of West Gojjam(Burie, Jabitehnan, and Fnoteselam), Ethiopia for fungal and aflatoxin analysis.The producers used a pre-validated structured questionnaire to obtain information on pepper production practices. Aspergillus species isolates were recovered using potato dextrose agar (PDA) medium and counting was through dilution method (cfu g-1). The pepper pods were ground to a fine powder for aflatoxin analysis using Enzyme-Linked Immunosorbent Assay(ELISA). The prevalence of infected samples revealed that, pre-harvest samples(51%) were less infected by Aspergillus species, compared to local markets (65 %) and storage (79 %).Aspergillus flavus species were recovered in pre-harvest samples, whilst A.niger were found in local market samples. Aflatoxin contamination at pre-harvest, storage, and local market were 10, 47, and 42 % with levels which ranged from non-detected to 10.6, 0.3 -17.1 and 3.1 -19.2 ppb, respectively.The mean aflatoxin concentration detected from storage samples (10.6 ppb)and local market (12.6 ppb)were found to be above the tolerable limits set byEU (5 ppb) in pepper products.From the findings in this study, proper drying, physical separation of molded pods and use of clean storage structures should be implemented along the production chain in order to reduce aflatoxin contamination in pepper in Ethiopia.

English

This study was conducted to assess the presence of pesticides residues in wheat from Misha woreda, Haiya Zone, Ethiopia. Samples of wheat were collected during the period December 2015 to August 2016. Gas chromatograph (GC-MS) detection was employed after Liquid-Liquid extraction (LLE). The concentration levels of eight pesticides have been investigated in both wheat samples in farm and purchased from storage facilities. Since the method was out of scope, it was validated before application to the analysis of these pesticides. The spiked recovery results for five analytes were within the acceptable international standard. The LOD value and LOQ value are below the LCC and MRL of the analyte. Method validation for this study maintained a RSD &lt;20% and percentage recoveries were in the range of 80-110%. The %RSD of all detected analytes was less than the acceptable international standard. Results show that out of the residues of eight analytes determined, four analytes (2,4-D; aldrin; Endosulfan; p,p-DDT) were detected in both field (pre harvest) samples and stored (post harvested) sample, whereas the remaining analytes were not detected at all. In general, the concentrations of these analytes in the wheat samples are in the order: 2, 4-D &gt;aldrin&gt;p,p-DDT &gt;Endosulfan. The study observed that from the detected analytes, none of them are above the international MRL values and suggested that stringent monitoring of use of pesticides in agriculture and food storage is required. Key words: Pesticide residue, wheat, Gas chromatography&ndash;mass spectrometry (GC-MS), method validation, maximum residue limit.

Validation of Reference Genes for RT-qPCR Studies of Gene Expression in Preharvest and Postharvest Longan Fruits under Different Experimental Conditions

Reverse transcription quantitative PCR (RT-qPCR) as the accurate and sensitive method is use for gene expression analysis, but the veracity and reliability result depends on whether select appropriate reference gene or not. To date, several reliable reference gene validations have been reported in fruits trees, but none have been done on preharvest and postharvest longan fruits. In this study, 12 candidate reference genes, namely, CYP, RPL, GAPDH, TUA, TUB, Fe-SOD, Mn-SOD, Cu/Zn-SOD, 18SrRNA, Actin, Histone H3, and EF-1a, were selected. Expression stability of these genes in 150 longan samples was evaluated and analyzed using geNorm and NormFinder algorithms. Preharvest samples consisted of seven experimental sets, including different developmental stages, organs, hormone stimuli (NAA, 2,4-D, and ethephon) and abiotic stresses (bagging and girdling with defoliation). Postharvest samples consisted of different temperature treatments (4 and 22°C) and varieties. Our findings indicate that appropriate reference gene(s) should be picked for each experimental condition. Our data further showed that the commonly used reference gene Actin does not exhibit stable expression across experimental conditions in longan. Expression levels of the DlACO gene, which is a key gene involved in regulating fruit abscission under girdling with defoliation treatment, was evaluated to validate our findings. In conclusion, our data provide a useful framework for choice of suitable reference genes across different experimental conditions for RT-qPCR analysis of preharvest and postharvest longan fruits.

Prevalence and antibiotic resistance pattern of Salmonella serovars in integrated crop‐livestock farms and their products sold in local markets

Major concern in the Mixed Crop-Livestock (MCL) farms, in which livestock and vegetables grown closely in the same facility, is cross-contamination of zoonotic bacterial pathogens especially Salmonella. To investigate the distribution of Salmonella serovars in MCL and their products, a total of 1287 pre-harvest samples from various farms and 1377 post-harvest samples from retail supermarkets in Maryland and Washington D.C. areas were collected and analysed. Atotal of 315 Salmonella isolates were recovered, with 17.44% and 5.88%, from MCL and conventional farms samples (P < 0.001). At post-harvest level, the prevalence of Salmonella was 30.95%, 19.83%, and 8.38% in chicken meat (P < 0.001) from farmers, organic, and conventional retail markets respectively, and 16.81% and 6.06% in produce products (P < 0.001) from farmers and organic retail markets, but none from conventional retail markets. From the isolated Salmonella, 34.50% was confirmed S. Typhimurium, followed by S. Heidelberg (10.86%) and S. Enteritidis (9.90%). The overall multi-antibiotic resistance in recovered Salmonella was 23.81% versus 4.55% in conventional and MCL farms (P = 0.004) and 66.67% versus 7.76% in conventional and farmers markets (P < 0.001). Overall the data reveals higher Salmonella risks in MCL farms' environment and their products sold in farmers markets and warrants taking necessary measures to limit Salmonella transmission.

Insecticide Efficacy and Timing for Control of Western Bean Cutworm (Lepidoptera: Noctuidae) in Dry and Snap Beans.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a recent pest of corn, dry,and snap beans, in the Great Lakes region, and best practices for its management in beans need to be established.Insecticide efficacy and application timing field studies, conducted in 2011–2013, determined that lambda-cyhalothrin and chlorantraniliprole were capable of reducing western bean cutworm feeding damage in dry beans from 2.3 to 0.4% in preharvest samples, and in snap beans from 4.8 to 0.1% of marketable pods, respectively. The best application timing in dry beans was determined to be 4–18 d after 50% egg hatch. No economic benefit was found when products were applied to dry beans, and despite high artificial inoculation rates, damage to marketable yield was relatively low. Thiamethoxam, methoxyfenozide, and spinetoram were also found to be effective at reducing western bean cutworm damage in dry bean to as low as 0.3% compared to an untreated control with 2.5% damaged pods. In snap beans, increased return on investment between CAD$400 and CAD$600 was seen with multiple applications of lambda-cyhalothrin, and with chlorantraniliprole applied 4 d after egg mass infestation.

Statewide and local recruitment of mourning doves in Missouri

Intensive harvests have the potential to greatly affect local mourning dove (Zenaida macroura) populations, a popular gamebird and songbird. To evaluate if recruitment was commensurate with harvest, we applied a ratio-based method to estimate local and statewide mourning dove recruitment across 7 public hunting areas in Missouri from 2005 to 2011. We estimated recruitment from preharvest adult sex ratios and harvest age ratios that incorporated various methods to address potential inherent biases (e.g., bias in the adults of unknown sex in preharvest samples, bias in unknown age wings, and local differential vulnerability; DV). Data from 356 radio-marked doves revealed a DV rate, where hatch year doves were, on average 2.7× more likely to be harvested than adult doves. Recruitment estimates for local areas were highly variable and in some cases, biologically unrealistic (e.g., >10 offspring/female), because of small preharvest sample sizes. However, data pooled statewide provided recruitment estimates of 3.1 offspring/female (±0.3 SE) or 4.1 offspring/female (±0.3 SE), assuming samples of unknown sex doves were female biased or male biased, respectively. Although statewide estimates agree with directly observed rates, the sex ratios and differential vulnerability comprising them vary considerably from what has been previously assumed. Whether preharvest sex ratios are biased from trapping methods has 2 important implications; either regional approaches have overestimated recruitment or the number of females in Missouri's population is much less than originally thought. Because each of these scenarios are important to understanding the effects of regional harvest management on Missouri's dove population, they highlight the importance of a better understanding of biases involved in estimating recruitment. © 2012 The Wildlife Society.

Occurrence of Fusarium Head Blight species and Fusarium mycotoxins in winter wheat in the Netherlands in 2009

Most recent information on the occurrence of Fusarium Head Blight species and related mycotoxins in wheat grown in the Netherlands dates from 2001. This aim of this study was to investigate the incidence and levels of Fusarium Head Blight species and Fusarium mycotoxins, as well as their possible relationships, in winter wheat cultivated in the Netherlands in 2009. Samples were collected from individual fields of 88 commercial wheat growers. Samples were collected at harvest from 86 fields, and 2 weeks before the expected harvest date from 21 fields. In all, 128 samples, the levels of each of seven Fusarium Head Blight species and of 12 related mycotoxins were quantified. The results showed that F. graminearum was the most frequently observed species at harvest, followed by F. avenaceum and M. nivale. In the pre-harvest samples, only F. graminearum and M. nivale were relevant. The highest incidence and concentrations of mycotoxins were found for deoxynivalenol, followed by zearalenone and beauvericin, both pre-harvest and at harvest. Other toxins frequently found – for the first time in the Netherlands – included T-2 toxin, HT-2 toxin, and moniliformin. The levels of deoxynivalenol were positively related to F. graminearum levels, as well as to zearalenone levels. Other relationships could not be established. The current approach taken in collecting wheat samples and quantifying the presence of Fusarium Head Blight species and related mycotoxins is an efficient method to obtain insight into the occurrence of these species and toxins in wheat grown under natural environmental conditions. It is recommended that this survey be repeated for several years to establish inter-annual variability in both species composition and mycotoxin occurrence.

Influence of the physiological stage and the content of soluble solids on the anthocyanin extractability of Vitis vinifera L. cv. Tempranillo grapes

The influence and the extent of the anthocyanin extractability from grape skins at different physiological stages and different soluble solids contents within each stage were investigated. For this purpose three different physiological stages (pre-harvest, harvest and over-ripening) and three soluble solids contents (22, 24 and 26°Brix) within each stage were taken into account using Vitis vinifera L. cv. Tempranillo.This study revealed the influence of physiological stages and soluble solids contents on the amounts of anthocyanins. The most important factor was the physiological stage although the soluble solid contents effect was also relevant, especially for anthocyanins monoglucosides. The highest contents in anthocyanins were found at pre-harvest, following by harvest and finally at over-ripening. Within each physiological stage, the relative abundance of acylated derivatives was influenced by the soluble solids contents. The percentages of acylated anthocyanins tend to decrease as the soluble solids contents.Differences in the anthocyanin extractabilities were highly influenced by the physiological stages and in a lesser extent by the soluble solids contents. The lowest extraction percentages were obtained in pre-harvest samples whatever soluble solids contents. Over-ripening samples present the lowest contents of anthocyanins but these compounds are easily released from tissues to the hydroalcoholic solution providing the highest extraction percentages. Generally, non-acylated anthocyanins were better extracted than the acylated anthocyanins.

Inter‐relationships ofSalmonellaStatus of Flock and Grow‐Out Environment at Sequential Segments in Broiler Production and Processing

In this study, we investigated how the likelihoods of Salmonella presence in various samples from broilers and their grow-out environment throughout one production cycle were related. Sixty-four broiler flocks from 10 complexes of two companies in the southern United States were included in the study. Samples from the gastrointestinal tracts of chicks, transport tray pads and litter and drag swabs from the house were collected on the day of placement of each flock. Approximately, 1 week before harvest, whole bird carcass rinses, caecum and crop samples were collected from birds from these same flocks. On the day of harvest, litter and drag swab samples were also taken from the house after the birds were removed. Upon arrival of the flocks at the processing plant, whole carcass rinses, caecum and crop samples were collected. As the flocks were processed, carcass rinses were collected just before the carcasses entered the immersion chill tank and as they exited the chill tank. Logistic regression was used to model the relationships between the likelihood of Salmonella in samples of each type collected at each sampling point and Salmonella frequencies in all the samples taken from the flock and grow-out environment at preceding production stages. The analysis demonstrated that increased likelihood of Salmonella contaminated carcasses entering the immersion chill tank was associated with higher contamination of the exteriors and crops of birds at arrival for processing as well as house environmental samples at the time of harvest and prior to placement. The best predictors of post-chill broiler carcass Salmonella status were the frequencies of Salmonella in the litter on the day of harvest and prior to placement. The immersion chilling appeared to disrupt some of the relationships between the processing plant and pre-harvest samples.

Effects of Processing and Cooking on the Levels of Pesticide Residues in Soybean Samples

The effects of processing and cooking on the levels of pesticide residues in soybean samples were investigated for 14 pesticides in pre-harvest samples. On soaking, the transfer ratios (%, total pesticide residue amount in product/that in soybean) of soaked soybean were greater than 60% for most of the pesticides investigated. The transfer ratio of soymilk ranged from 37% to 92%, and that of tofu ranged from 7% to 63%. The processing factor (Pf, the concentration (mg/kg) of pesticide in product/that in soybean) of tofu ranged from 0.026 to 0.28. These values varied among pesticides. There was a high correlation between the log P(ow) and the transfer ratio of tofu. The test described here should be useful to obtain the transfer ratios of pesticide residues in processing and/or cooking steps.

Effects of Processing and Cooking on the Levels of Pesticide Residues in Rice Samples

The effects of processing and cooking on the levels of pesticide residues in rice samples were investigated for 11 pesticides in pre-harvest (9 pesticides) and post-harvest (4 pesticides) samples. In the polishing process, the transfer ratio (%, total pesticide residue amount in product/that in brown rice) of rice bran ranged from 40% to 106%, and the transfer ratio of polished rice ranged from 9% to 65% in pre-harvest samples. These values varied from pesticide to pesticide. The processing factor (the concentration (mg/kg) of pesticide in product/that in the brown rice) of polished rice ranged from 0.11 to 0.73. The loss of pesticides during processing and/or cooking did not correlate to any single physical or chemical property. Investigation of changes of pesticide residues during processing and/or cooking is useful not only to establish MRLs, but also to recognize actual levels of pesticide residues in food.

Effects of Processing and Cooking on the Levels of Pesticide Residues in Wheat Samples

The effects of processing and cooking on the levels of pesticide residues in wheat samples were investigated for 13 pesticides in pre-harvest (Pre, 9 pesticides) and post-harvest (Post, 6 pesticides) samples. In the milling process, the transfer ratios (%, total pesticide residue amount in product/that in wheat grain) of wheat bran were greater than 70% and 80% for pre-harvest and post-harvest samples, respectively. The transfer ratios of flour ranged from 1.7% to 23% (Pre) and 4.0% to 11% (Post). There was no significant difference in transfer ratio among the pesticides investigated. The processing factors (Pf, the concentration (mg/kg) of pesticide in product/that in the wheat grain) of flour ranged from 0.030 to 0.40 (Pre) and 0.069 to 0.18 (Post). The values in pre-harvest samples were higher than those in post-harvest samples. Investigation of changes of pesticide residues during processing and/or cooking is useful not only to establish MRLs, but also to recognize actual levels of pesticide residues in food.

Ecological survey of Saccharomyces cerevisiae strains from vineyards in the Vinho Verde Region of Portugal

One thousand six hundred and twenty yeast isolates were obtained from 54 spontaneous fermentations performed from grapes collected in 18 sampling sites of three vineyards (Vinho Verde Wine Region in northwest Portugal) during the 2001–2003 harvest seasons. All isolates were analyzed by mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) and a pattern profile was verified for each isolate, resulting in a total of 297 different profiles, that all belonged to the species Saccharomyces cerevisiae. The strains corresponding to seventeen profiles showed a wider temporal and geographical distribution, being characterized by a generalized pattern of sporadic presence, absence and reappearance. One strain (ACP10) showed a more regional distribution with a perennial behavior. In different fermentations ACP10 was either dominant or not, showing that the final outcome of fermentation was dependent on the specific composition of the yeast community in the must. Few of the grape samples collected before harvest initiated a spontaneous fermentation, compared to the samples collected after harvest, in a time frame of about 2 weeks. The associated strains were also much more diversified: 267 patterns among 1260 isolates compared to 30 patterns among 360 isolates in the post- and pre-harvest samples, respectively. Fermenting yeast populations have never been characterized before in this region and the present work reports the presence of commercial yeast strains used by the wineries. The present study aims at the development of strategies for the preservation of biodiversity and genetic resources as a basis for further strain development.

Salmonella enterica Serovars from Pigs on Farms and after Slaughter and Validity of Using Bacteriologic Data To Define Herd Salmonella Status

The primary objective of this study was to evaluate the validity of using data obtained from slaughtered pigs for farm-level epidemiologic studies of Salmonella. The study involved groups of pigs from five farms. Salmonella isolates were obtained from on-farm samples, and a total of 370 on-farm and an additional 486 isolates from samples collected after commercial slaughter were subsequently tested. Preharvest samples included feces of individual animals from defined groups of nursery and finishing pigs on commercial farms and swabs from trucks. Postslaughter samples were cecal contents and mesenteric lymph node samples. The concordance between Salmonella serovars isolated from on-farm samples and those serovars isolated after slaughter varied widely among farms. Results of paired lymph node and cecal cultures were strongly associated (odds ratio, 7.0), but the agreement between on-farm and postslaughter results at the pig level was poor (κ = 0.34). The results support recent findings that risk of exposure to Salmonella during transport and lairage remains a concern under contemporary industry conditions. The findings further imply that slaughter plant studies based on phenotyping of Salmonella alone (such as serovars) may not reliably indicate the Salmonella status of commercial swine farms.