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1.
The co-occurrence of the major Fusarium mycotoxin deoxynivalenol (DON) and its conjugate deoxynivalenol-3-glucoside (DON-3-Glc) has been documented in infected wheat. This study reports on the fate of this masked DON within milling and baking technologies for the first time and compares its levels with those of the free parent toxin. The fractionation of DON-3-Glc and DON in milling fractions was similar, tested white flours contained only approximately 60% of their content in unprocessed wheat grains. No substantial changes of both target analytes occurred during the dough preparation process, i.e. kneading, fermentation, and proofing. However, when bakery improvers enzymes mixtures were employed as a dough ingredient, a distinct increase up to 145% of conjugated DON-3-Glc occurred in fermented dough. Some decrease of both DON-3-Glc and DON (10 and 13%, respectively, compared to fermented dough) took place during baking. Thermal degradation products of DON, namely norDON A, B, C, D, and DON-lactone were detected in roasted wheat samples and baked bread samples by means of UPLC-Orbitrap MS. Moreover, thermal degradation products derived from DON-3-Glc were detected and tentatively identified in heat-treated contaminated wheat and bread based on accurate mass measurement performed under the ultrahigh mass resolving power. These products, originating from DON-3-Glc through de-epoxidation and other structural changes in the seskviterpene cycle, were named norDON-3-Glc A, B, C, D, and DON-3-Glc-lactone analogically to DON degradation products. Most of these compounds were located in the crust of experimental breads.  相似文献   

2.
When conservation tillage is practised in agriculture, plant residues remain on the soil surface for soil protection purposes. These residues should be widely decomposed within the following vegetation period as microbial plant pathogens surviving on plant litter may endanger the currently cultivated crop. Important soil-borne fungal pathogens that preferably infect small grain cereals belong to the genus Fusarium. These pathogens produce the mycotoxin deoxynivalenol (DON), a cytotoxic agent, in infected cereal organs. This toxin frequently occurs in cereal residues like straw. So far it is unclear if DON degradation is affected by members of the soil food web within decomposing processes in the soil system. For this purpose, a microcosm study was conducted under controlled laboratory conditions to investigate the degradation activity of the earthworm species Lumbricus terrestris when exposed to Fusarium-infected wheat straw being contaminated with DON.Highly Fusarium-infected and DON-contaminated straw seemed to be more attractive to L. terrestris because it was incorporated faster into the soil compared with straw infected and contaminated at low levels. This is supported by a greater body weight gain (exposure time 5 weeks) and smaller body weight loss (exposure time 11 weeks) of L. terrestris, respectively, when highly contaminated straw was offered for different time periods.Furthermore, L. terrestris takes part in the efficient degradation of both Fusarium biomass and DON occurring in straw in close interaction with soil microorganisms. Consequently, earthworm activity contributes to the elimination of potentially infectious plant material from the soil surface.  相似文献   

3.
A sensitive method is described for determination of nivalenol (NIV) and deoxynivalenol (DON) in cereals by using reverse phase liquid chromatography and UV detection at 222 nm. The sample is extracted with acetonitrile-water (85 + 15) and an aliquot is purified by passage through a combined column of cation exchange resin and alumina-carbon (20 + 1). Analysis at this stage is possible with some samples but the method recommends passing an aliquot through a carbon minicolumn after evaporation and solubilization in methanol. Interference from coextracted compounds at this point is negligible. Recoveries of both NIV and DON from spiked extracts taken through the full method were in the range 83-94%. The relative standard deviation, based on 5 replicate determinations from each of 2 corn samples, was approximately 5% for both NIV and DON. With a 10 microL injection, the minimum contamination (3 X signal/noise ratio) able to be detected in cereal samples was about 0.015 micrograms NIV/g and 0.05 micrograms DON/g. The cleaned up extracts are also suitable for analysis by gas chromatography.  相似文献   

4.
Conjugated mycotoxins, in which the toxin is usually bound to a more polar substance like glucose, are referred to as masked mycotoxins, as these substances escape routine detection methods but can release their toxic precursors after hydrolysis. This is the first report on the natural occurrence of a glucoside of deoxynivalenol (DON) in Fusarium-infected wheat and maize. To obtain appropriate standards, we chemically synthesized deoxynivalenol-3-beta-D-glucopyranoside (DON-3-glucoside) and deoxynivalenol-15-beta-D-glucopyranoside (DON-15-glucoside). The synthesis products were characterized by liquid chromatography-tandem mass spectrometry. The DON-glucosides showed different collision-induced dissociation (CID) fragmentation behaviors and could therefore be distinguished. Wheat plants were either treated with DON (n = 52) or with Fusarium spp. (n = 4) at anthesis, and after harvest, wheat ears were analyzed for DON and DON-glucosides. All 56 treated wheat samples contained DON and a DON-glucoside with the same retention time, molecular mass, and CID fragmentation behavior as the synthetic DON-3-glucoside. Moreover, the DON-glucoside was also found in two out of three analyzed naturally DON-contaminated maize and in five out of five naturally contaminated wheat samples, in a range from 4 to 12% of the DON concentration. To further confirm the identity of the DON-glucoside, the compound was isolated from wheat extracts and characterized as DON-3-glucoside with NMR. The results of this study indicate the importance to consider both DON and DON-3-glucoside with regard to food and feed safety.  相似文献   

5.
Three batches of oats were extruded under four combinations of process temperature (150 or 180 degrees C) and process moisture (14. 5 and 18%). Two of the extrudates were evaluated by a sensory panel, and three were analyzed by GC-MS. Maillard reaction products, such as pyrazines, pyrroles, furans, and sulfur-containing compounds, were found in the most severely processed extrudates (high-temperature, low-moisture). These extrudates were also described by the assessors as having toasted cereal attributes. Lipid degradation products, such as alkanals, 2-alkenals, and 2, 4-alkadienals, were found at much higher levels in the extrudates of the oat flour that had been debranned. It contained lower protein and fiber levels than the others and showed increased lipase activity. Extrudates from these samples also had significantly lower levels of Maillard reaction products that correlated, in the sensory analysis, with terms such as stale oil and oatmeal. Linoleic acid was added to a fourth oat flour to simulate the result of increased lipase activity, and GC-MS analysis showed both an increase in lipid degradation products and a decrease in Maillard reaction products.  相似文献   

6.
Thermal degradation studies of food melanoidins   总被引：1，自引：0，他引：1  
Food melanoidins were isolated from bread crust, coffee, and tomato sauce and their composition was investigated by thermal degradation. Among the generated volatiles, important food flavor compounds were detected: in particular furans, carbonyl compounds, 1,3-dioxolanes, pyrroles, pyrazines, pyridines, thiophenes, and phenols. The results indicated that the isolated melanoidin fractions mainly consisted of compounds formed from carbohydrates and their degradation products. Besides proteins, other food constituents were incorporated in the melanoidin structure as well, such as lipid oxidation products in tomato melanoidins and phenolic compounds in coffee melanoidins. A comparison of the thermal generation of volatiles between these food-derived melanoidins and model melanoidins prepared from a single carbonyl compound and an amino acid showed that the degradation pattern of food melanoidins is quite different from that obtained from a glucose-glycine model system.  相似文献   

7.
This study aimed to achieve the conversion of cereal proteins to the alternative end products glutamate or γ-aminobutyrate (GABA). Rye malt, fungal proteases, and lactobacilli were employed to convert wheat gluten or barley proteins. Glutamate and GABA formations were strain-dependent. Lactobacillus reuteri TMW1.106 and Lactobacillus rossiae 34J accumulated glutamate; L. reuteri LTH5448 and LTH5795 accumulated GABA. Glutamate and GABA accumulation by L. reuteri TMW1.106 and LTH5448 increased throughout fermentation time over 96 h, respectively. Peptides rather than amino acids were the main products of proteolysis in all doughs, and barley proteins were more resistant to degradation by rye malt proteases than wheat gluten. However, addition of fungal protease resulted in comparable degradation of both substrates. Glutamate and GABA accumulated to concentrations up to 63 and 90 mmol kg(-1) DM, respectively. Glutamate levels obtained through bioconversion of cereal proteins enable the use of hydrolyzed cereal protein as condiment.  相似文献   

8.
Evolution of toxicity upon hydrolysis of fenoxaprop-p-ethyl   总被引：2，自引：0，他引：2  
Hydrolysis of fenoxaprop-p-ethyl (FE), a widely used herbicide, was studied in aqueous buffer solutions at pH ranging from 4.0 to 10.0. The degradation kinetics, strongly dependent on pH values, followed first-order kinetics. FE was relatively stable in neutral media, whereas it degraded rapidly with decreasing or increasing pH. In acidic conditions (pH = 4, 5), the benzoxazolyl-oxy-phenyl ether linkage of FE was cleaved to form ethyl 2-(4-hydroxyphenoxy)propanoate (EHPP) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB). While in basic conditions (pH = 8, 9, 10), herbicidal activity fenoxaprop-p (FA) was formed via breakdown of the ester bond of the herbicide. Both the two pathways were concurrent in neutral conditions (pH = 6, 7). Toxicity studies on Daphnia magna showed that FE was most toxic to D. magna with 48 h EC(50) of 14.3 micromol/L, followed by FA (43.8 micromol/L), CDHB (49.8 micromol/L), and EHPP (333.1 micromol/L). Mode of toxic action analysis indicated that EHPP exhibited toxicity via polar narcosis, whereas CDHB belonged to reactive acing compound. The mixture toxicity of CDHB and EHPP was nonadditive and can be predicted by a response addition model. Therefore, the evaluation of overall FE toxicity to D. magna in the aquatic systems needs to consider the degradation of FE.  相似文献   

9.
OBJECTIVES: To estimate the intakes of cereal and dairy products and their contribution to nutrient intakes in men and women from the Republic of Ireland with a view to formulating food-based dietary guidelines. DESIGN: The North/South Ireland Food Consumption Survey established a database of habitual food and drink consumption using a 7-day food diary. From this database all cereal and dairy products from recipes and identifiable sources were identified and a new database was generated from which analysis of the role of cereal and dairy products in the diet was carried out. RESULTS: Almost 100% of the population consumed cereal and dairy products over the course of the survey week. In general, men consumed significantly more cereal and dairy products than did women (P<0.05). Cereal products made an important contribution to the mean daily intakes of energy (26%), protein (21%), fat (13%), carbohydrate (41%), fibre (45%), iron (43%) and folate (27%). Dairy products also contributed largely to the mean daily intakes of energy (11%), protein (14%), fat (17%), calcium (48%), phosphorus (24%) and vitamin A (27%). Analysis of nutrient intakes across tertiles of cereal and dairy consumption showed that high consumers of wholemeal bread, breakfast cereals, reduced-fat milk and yoghurt had lower fat and higher carbohydrate, fibre and micronutrient intakes than low consumers of these foods. CONCLUSIONS: Findings from the present study could be used to develop effective health strategies to implement changes in cereal and dairy consumption that could alter fat, fibre and micronutrient intakes in the diet.  相似文献   

10.
To deduce the structure of the large array of compounds arising from the transformation pathway of 6-methoxybenzoxazolin-2-one (MBOA), the combination of isotopic substitution and liquid chromatography analysis with mass spectrometry detection was used as a powerful tool. MBOA is formed in soil when the cereal allelochemical 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) is exuded from plant material to soil. Degradation experiments were performed in concentrations of 400 microg of benzoxazolinone/g of soil for MBOA and its isotopomer 6-trideuteriomethoxybenzoxazolin-2-one ([D3]-MBOA). Previously identified metabolites 2-amino-7-methoxyphenoxazin-3-one (AMPO) and 2-acetylamino-7-methoxyphenoxazin-3-one (AAMPO) were detected. Furthermore, several novel compounds were detected and provisionally characterized. The environmental impact of these compounds and their long-range effects are yet to be discovered. This is imperative due to the enhanced interest in exploiting the allelopathic properties of cereals as a means of reducing the use of synthetic pesticides.  相似文献   

11.
Plant-derived allelochemicals such as those produced by glucosinolate hydrolysis in Brassica napus, or rapeseed, are viable alternatives to synthetic compounds for the control of soil-borne plant pests. However, allelochemical production and residence times in field soils have not been determined. Soil samples were taken at 0-7.5 and 7.5-15 cm during a period of 3 weeks following plow-down of two winter rapeseed cultivars (Humus and Dwarf Essex). Soil samples were extracted with dichloromethane and analyzed using gas chromatography. Nine glucosinolate degradation products were identified-five isothiocyanates, three nitriles, and one oxazolidinethione. Maximum concentrations were observed 30 h after plow-down. Compounds derived from 2-phenylethyl glucosinolate, the principal glucosinolate in rapeseed roots, dominated the profile of degradation products. Shoot glucosinolates left few traces. This indicates that rapeseed roots may be a more important source of toxic fumigants than above-ground parts of the plant.  相似文献   

12.
Near-infrared reflectance spectra of cereal food products were acquired with a commercial dual-diode-array (Si, InGaAs) spectrometer customized to allow rapid acquisition of scans of intact breakfast cereals, snack foods, whole grains, and milled products. Substantial gains in the performance of multivariate calibration models generated from these data were obtained by a computational strategy that systematically analyzed the performance of various spectral windows. The calibration model based on 137 cereal food products determined the total dietary fiber (TDF) content of a test set of 45 intact diverse cereal food products with root-mean-squared error of cross-validation of between 1.8 and 2.0% TDF, relative to the laborious enzymatic-gravimetric reference method. The calibration performance is adequate to estimate TDF over the range of values found in diverse types of cereal food products (0.7-50.1%). The method requires no sample preparation and is relatively unaffected by specimen moisture content.  相似文献   

13.
Avena fatua L. (wild oat) and Lolium rigidum Gaud. (rigid ryegrass) are highly problematic weeds affecting a wide variety of cereal crops worldwide. The fact that both of these weeds have developed resistance to several herbicide groups made them optimal candidates as target organisms for ongoing research about the potential application of allelochemicals and analogue compounds as natural herbicide models. Benzoxazinones, a family of natural allelochemicals present in corn, wheat, and rye, including 2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one and 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one, together with some degradation products, found in crop soils as well as in other systems, and some synthetic analogues of them were tested on wild oat and rigid ryegrass seeds; the results were statistically treated, and some structure-activity relationships, useful in further development of natural herbicide models, were elucidated. The most active compounds were the synthetic benzoxazinone 2-acetoxy-(2H)-1,4-benzoxazin-3(4H)-one and the degradation product 2-aminophenoxazin-3-one, with highly significant inhibition on the development of both weeds. The ecological role of these compounds is discussed by considering both degradability and phytotoxicity. The bioactivity of aminophenoxazines has been correlated by their aqueous solubility-lipophilicity predicted by means of computational methods.  相似文献   

14.
Aimed at elucidating intense bitter-tasting molecules in coffee, various bean ingredients were thermally treated in model experiments and evaluated for their potential to produce bitter compounds. As caffeic acid was found to generate intense bitterness reminiscent of the bitter taste of a strongly roasted espresso-type coffee, the reaction products formed were screened for bitter compounds by means of taste dilution analysis, and the most bitter tastants were isolated and purified. LC-MS/MS as well as 1-D/2-D NMR experiments enabled the identification of 10 bitter compounds with rather low recognition threshold concentrations ranging between 23 and 178 micromol/L. These bitter compounds are the previously unreported 1,3-bis(3',4'-dihydroxyphenyl) butane, trans-1,3-bis(3',4'-dihydroxyphenyl)-1-butene, and eight multiply hydroxylated phenylindanes, among which five derivatives are reported for the first time. In addition, the occurrence of each of these bitter compounds in a coffee brew was verified by means of LC-MS/MS (ESI-) operating in the multiple reaction monitoring (MRM) mode. The structures of these bitter compounds show strong evidence that they are generated by oligomerization of 4-vinylcatechol released from caffeic acid moieties upon roasting.  相似文献   

15.
Occurrence of PFCs and PBDEs in Landfill Leachates from Across Canada   总被引：2，自引：0，他引：2  
Polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) are both classes of persistent organic pollutants with potential major health and environmental concerns. Many PBDE- and PFC-containing products are ultimately discarded in landfills. In samples from 28 landfills and dumpsites across Canada, PBDEs and PFCs were detected in almost all landfill leachate samples, with concentrations up to 1,020 and 21,300?ng/L, respectively. Mean concentrations were 166?ng/L for PBDEs and 2,950?ng/L for PFCs. Landfill leachates from southern Canada generally had greater concentrations of PBDEs and PFCs than those from northern Canada. The dominant compounds were decabromodiphenyl ether (BDE-209) (mean contribution 52 %) for the PBDEs and perfluorohexanoic acid (mean contribution 25 %) for the PFCs. There were strong correlations for some compounds within each contaminant class, such as the major congeners in the penta-BDE commercial mix (BDE-47, BDE-99, and BDE-100). Estimated average ??PBDE and ??PFC loadings from an urban landfill to the environment were calculated to be 3.5 and 62?tonnes/year, respectively.  相似文献   

16.
Meadowfoam (Limnanthes alba L.) is a herbaceous winter-spring annual grown as a commercial oilseed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products, and therefore the meal may have potential in the management of soilborne pathogens. To maximize the pest-suppressive potential of meadowfoam seed meal, it would be beneficial to know the toxicity of individual glucolimnanthin degradation products against specific soilborne pathogens. Meloidogyne hapla second-stage juveniles (J2) and Pythium irregulare and Verticillium dahliae mycelial cultures were exposed to glucolimnanthin as well as its degradation products. Glucolimnanthin and its degradation product, 2-(3-methoxyphenyl)acetamide, were not toxic to any of the soilborne pathogens at concentrations up to 1.0 mg/mL. Two other degradation products, 2-(3-methoxymethyl)ethanethioamide and 3-methoxyphenylacetonitrile, were toxic to M. hapla and P. irregulare but not V. dahliae. The predominant enzyme degradation product, 3-methoxybenzyl isothiocyanate, was the most toxic compound against all of the soilborne pathogens, with M. hapla being the most sensitive with EC(50) values (0.0025 ± 0.0001 to 0.0027 ± 0.0001 mg/mL) 20-40 times lower than estimated EC(50) mortality values generated for P. irregulare and V. dahliae (0.05 and 0.1 mg/mL, respectively). The potential exists to manipulate meadowfoam seed meal to promote the production of specific degradation products. The conversion of glucolimnanthin into its corresponding isothiocyanate should optimize the biopesticidal properties of meadowfoam seed meal against M. hapla, P. irregulare, and V. dahliae.  相似文献   

17.
The potential for the Fusarium mycotoxins 4-deoxynivalenol (DON) and zearalenone (ZON) to enter the human food chain through contaminated eggs was assessed using a controlled feed study. Four groups of laying hens (eight in each group) were fed a diet that included differing amounts of naturally contaminated wheat containing DON ( approximately 20 mg kg(-1)) and ZON (0.5 mg kg(-1)). Eggs were collected and pooled from each group on a daily basis. Pooled samples were analyzed by liquid chromatography with mass spectrometry detection (LC-MS/MS). The method allowed DON, other type B trichothecenes, ZON, and its metabolites to be determined in a single multi-residue analysis. The selectivity of the MS/MS procedure allowed cleanup to be minimized (for DON, cleanup by immunoaffinity column was used) or eliminated (for ZON). The limits of detection of 0.01 microg kg(-1) for DON and 0.1 microg kg(-1) for ZON in eggs were lower than previously published methods. None of the samples analyzed had detectable levels of ZON or its metabolites. Although maximum levels of DON contamination (10 mg kg(-1) feed) were relatively high, no adverse effects were observed on egg production. On the basis of the determined DON levels in the hen's diet and the determined levels of DON in the corresponding eggs, transmission rates of 15 000:1, 18 000:1, and 29 000:1 for treatment levels 5, 7.5, and 10 mg DON kg(-1) feed, respectively, were found. These results show that, although eggs could be a human exposure route for DON, the levels are insignificant compared to the other sources, although the presence of metabolites of DON was not studied.  相似文献   

18.
Deoxynivalenol (DON) is a toxic secondary metabolite produced by molds of the Fusarium genus and is known to cause a spectrum of diseases in animals such as vomiting and gastroenteritis. It is found in cereals and cereal products as most processing techniques lead only to a partial reduction of deoxynivalenol levels. One technique with a reported relatively high impact on deoxynivaleol decomposition is extrusion cooking. In the current work, systematic studies of a range of physicochemical parameters, such as temperature, moisture, compression, residence time in the extruder, pH value, and protein content, on their impact on deoxynivalenol decomposition during extrusion cooking were performed. The analysis of deoxynivalenol was made by high-performance liquid chromatography--tandem mass spectrometry using a quick, easy, cheap, effective, rugged, and safe-based cleanup with 15-d(1)-deoxynivalenol as an internal standard. It could be shown that the reduction of deoxynivalenol levels is dependent on a set of parameters partially interacting with each other. Especially the moisture content and compression are key factors for the reduction of deoxynivalenol levels. A correlation between residence time of the mycotoxin in the extruder and deoxynivalenol degradation was also observed when screws without a compression factor were used. Generally, the reduction of deoxynivalenol levels was increased by the use of screws with a high compression factor. As known from cooking, deoxynivalenol could also be easily degraded by extrusion under alkaline conditions. Furthermore, an increase of the protein content of the starting material resulted in higher reduction rates of deoxynivalenol.  相似文献   

19.
Fusarium toxins, Alternaria toxins, and ergot alkaloids represent common groups of mycotoxins that can be found in cereals grown under temperate climatic conditions. Because most of them are chemically and thermally stable, these toxic fungal secondary metabolites might be transferred from grains into the final products. To get information on the commensurate contamination of various cereal-based products collected from the Czech retail market in 2010, the occurrence of "traditional" mycotoxins such as groups of A and B trichothecenes and zearalenone, less routinely determined Alternaria toxins (alternariol, alternariol monomethyl ether and altenuene), ergot alkaloids (ergosine, ergocryptine, ergocristine, and ergocornine) and "emerging" mycotoxins (enniatins A, A1, B, and B1 and beauvericin) were monitored. In a total 116 samples derived from white flour and mixed flour, breakfast cereals, snacks, and flour, only trichothecenes A and B and enniatins were found. Deoxynivalenol was detected in 75% of samples with concentrations ranging from 13 to 594 μg/kg, but its masked form, deoxynivalenol-3-β-d-glucoside, has an even higher incidence of 80% of samples, and concentrations ranging between 5 and 72 μg/kg were detected. Nivalenol was found only in three samples at levels of 30 μg/kg. For enniatins, all of the samples investigated were contaminated with at least one of four target enniatins. Enniatin A was detected in 97% of samples (concentration range of 20-2532 μg/kg) followed by enniatin B with an incidence in 91% of the samples (concentration range of 13-941 μg/kg) and enniatin B1 with an incidence of 80% in the samples tested (concentration range of 8-785 μg/kg). Enniatin A1 was found only in 44% of samples at levels ranging between 8 and 851 μg/kg.  相似文献   

20.
Numerous investigations concerning Maillard degradation of carbohydrates clearly depict the important impact of α-dicarbonyl compounds on changes occurring during preparation of food or physiological processes in vivo. To study the formation of these reactive intermediates during degradation of maltose in the presence of lysine, α-dicarbonyl compounds were isolated, identified and quantified after reaction with o-phenylenediamine to form their stable quinoxaline derivatives. Maltosone and 1,4-dideoxyglucosone were synthesized and incubated independently with lysine to investigate follow-up products and to gain further insights into the complex degradation mechanisms. Glyoxylic acid as a dicarbonyl structure and 5,6-dihydroxy-2,3-dioxohexanal as a 1,2,3-tricarbonyl compound were established as novel Maillard degradation products of maltose. Conducted experiments unequivocally demonstrated that inter- and intramolecular redox reactions are of major importance during degradation of disaccharides. 1,4-Dideoxyglucosone, 1-lysino-1,4-dideoxyglucosone, 5,6-dihydroxy-2,3-dioxohexanal, 3,4-dideoxypentosone and glyoxylic acid were found to be the central intermediates involved in the redox chemistry. With the present study we deliver a comprehensive overview on the mechanisms behind α-dicarbonyl compounds evolving from Maillard degradation of maltose.  相似文献   

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