Effect of cleaning, milling, and baking on deoxynivalenol in wheat.

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.     

Deoxynivalenol in Mehlproben des Jahres 1999 aus dem Einzelhandel

To study the levels of deoxynivalenol (DON) in retail cereal products, wheat and rye samples were purchased in 1999 from supermarkets and “organic food” shops in Munich, Germany. DON was analysed by an enzyme immunoassay (EIA), 78 of these samples were additionally analysed by HPLC. The following contamination rates (%) and mean DON levels were found: wheat flour type 405 (n=42): 71%, 200 µg/kg; flour type 550 (n=9): 33%, 410 µg/kg; flour type 1050 (n=11): 91%, 370 µg/kg; bread-baking wheat premixes (n=14): 79%, 210 µg/kg; whole grain flour (n=20): 65%, 300 µg/kg; whole grain wheat (n=8): 75%, 280 µg/kg, wheat bran (n=20): 85%, 830 µg/kg; rye flour and grits (n=7): 29%, 120 µg/kg. HPLC confirmed the results obtained by EIA. Further analysis of 16 wheat flour (405) samples in May 2000 showed a similar frequency (69%) and mean DON level (270 µg/kg) as for samples from 1999. It is concluded that with DON levels in wheat for human consumption ranging from 200–400 µg/kg, the intake of DON has to be taken seriously in the light of the temporary tolerable daily intake of 1 µg DON per kg body weight as proposed within the European Union.     

小麦中脱氧雪腐镰刀菌烯醇酶联免疫吸附测定方法的研究

用B淋巴细胞杂交瘤技术制备了能稳定分泌抗脱氧雪腐镰刀菌烯醇(DON)单克隆抗体的杂交瘤细胞株,命名为3D7.3D7的亚类为lgG_1.运用该抗体,建立了检测小麦中DON的间接竞争性酶联免疫吸附测定法.该法最低检出量为5ng/ml,敏感范围为5—1000ng/ml;平均回收率为96.6—107.3%;精密度为6.2—13.3%.运用该方法,检测了10份小麦样品.均为阳性,其含量为56.4—1002.0ppb.     

Distinct Distribution of Deoxynivalenol,Nivalenol, and Ergosterol in <Emphasis Type="Italic">Fusarium</Emphasis>-infected Japanese Soft Red Winter Wheat Milling Fractions

The occurrence of mycotoxins in small grain cereals and their retention in final products are serious concerns for food safety. Previously, we investigated the fate of deoxynivalenol and nivalenol in a Japanese soft red winter wheat cultivar during milling and we found that deoxynivalenol and/or nivalenol was readily distributed among flours for human consumption. In the present study, we analyzed the ergosterol concentrations in the milling fractions as an index of fungal biomass to elucidate the relationship between deoxynivalenol/nivalenol accumulation and fungal invasion into the grain, after the in-house validation of an analytical method for quantifying ergosterol in the resulting milling fractions (patent flour, low-grade flour, bran, and shorts). Using three samples with different levels of deoxynivalenol and/or nivalenol contamination, the contents of deoxynivalenol/nivalenol and ergosterol in the resulting milling fractions were evaluated. The concentration of ergosterol was always lowest in patent flour and highest in bran or shorts, indicating that most of the fungi is retained in the outer layers of grain (bran and shorts) even in highly contaminated grain. On the other hand, the concentrations of deoxynivalenol and nivalenol were similar in the low-grade and patent flours and only slightly lower than in the medium-level and high-level contaminated grains. Moreover, the percentage distribution of ergosterol was higher in bran than in other fractions in all cases, which differed from that of deoxynivalenol/nivalenol. This result indicates the diffusion of deoxynivalenol/nivalenol inside the grain that is independent of fungal invasion.     

<Emphasis Type="Italic">Fusarium</Emphasis> mycotoxins in conventionally and organically grown grain from Thuringia/Germany

Thefusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZON) were determined in conventionally and organically grown grain harvested 1998 in Thuringia/Germany. A total of 196 wheat samples and 69 rye samples was analysed.In this year with heavy rainfalls during the summer months, high concentrations offusarium mycotoxins were typical in grain grown in Germany, as the DON concentrations found here. DON concentrations in conventionally grown wheat were found to be significantly higher than in organically grown wheat. 69% of the conventionally grown wheat were tested positive, containing a mean concentration of 1540 µg/kg DM. In 54% of the organically grown wheat samples DON was detected with a mean value of 760 µg/kg DM. DON concentration in rye and ZON concentration in wheat showed similar tendencies.The different cultivars of conventionally grown wheat showed large differences in DON contamination.     

A case report on a minor contamination of nivalenol in cereals harvested in Canada

An investigation for the occurrence of nivalenol (NIV), deoxynivalenol (DON) and zearalenone (ZEN) in cereals (ten wheat, one rye and one corn) harvested in Canada have been carried out using a procedure, which is rapid and sensitive for Fusarium mycotoxins. NIV, DON and ZEN were detected in 4, 9 and 9 out of ten wheat samples, and their average levels in the positives were 23 ng/g, 1257 ng/g and 9 ng/g, respectively. One rye and one corn were also contaminated with a minor amount of NIV. This is the first evidence for the natural occurrence of NIV in cereals grown in Canada, though its level was far less than DON.     

Decontamination ofFusarium mycotoxins,nivalenol, deoxynivalenol,and zearalenone,in barley by the polishing process

Korean dehusked and unhusked barley naturally contaminated withFusarium mycotoxins were polished using a Satake Grain Testing Mill. The pearled barley and bran fractions with different degrees of polishing were analyzed for nivalenol (NIV) and deoxynivalenol (DON) by gas chromatography with an electron capture detector, and for zearalenone (ZEN) by high-performance liquid chromatography with a fluorescence detector. NIV was detected in all the pearled barley fractions, but DON and ZEN were not detected in ≥27 % pearled barley fractions from dehusked barley and ≥36% pearled barley fractions from unhusked barley. However, for all degrees of polishing, NIV, DON, and ZEN were detected in bran fractions. The levels of NIV, DON, and ZEN in the bran fractions increased several fold over the original barley. Polishing was effective in removing DON and ZEN from the naturally contaminated barley, but not NIV.     

Immunochemical assessment of mycotoxins in 1989 grain foods: evidence for deoxynivalenol (vomitoxin) contamination.

To assess the potential for mycotoxin contamination of the human food supply following the 1988 U.S. drought, 92 grain food samples were purchased from retail outlets in the summer of 1989 and surveyed for aflatoxin B1, zearalenone, and deoxynivalenol (DON [vomitoxin]) by monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Only one sample (buckwheat flour) was found to contain aflatoxin B1 (12 ng/g), whereas zearalenone was found in 26% of the samples at a mean concentration of 19 ng/g. In contrast, the DON ELISA was positive in 50% of the samples at a detection level of 1.0 micrograms/g. Between 63 and 88% of corn cereals, wheat flour/muffin mixes, rice cereals, and corn meal/muffin mixes yielded positive results for DON, whereas 25 to 50% of oat cereals, wheat- and oat-based cookies/crackers, corn chips, popcorn, and mixed-grain cereals were positive for DON. The mean DON content of the positive samples was 4.0 micrograms/g, and the minimum and maximum levels were 1.2 and 19 micrograms/g, respectively. When positive ELISA samples were also analyzed by high-performance liquid chromatography, a strong correlation between the two methods was found. The presence of DON in the two highest samples, corn meal and mixed-grain cereal, which contained 19 and 16 micrograms/g, respectively, was quantitatively confirmed by gas chromatography-mass spectrometry. The results indicated that DON was present in 1989 retail food products at concentrations that exceeded those found in previous market surveys and that have been experimentally associated with impaired animal health.     

Immunochemical assessment of mycotoxins in 1989 grain foods: evidence for deoxynivalenol (vomitoxin) contamination

To assess the potential for mycotoxin contamination of the human food supply following the 1988 U.S. drought, 92 grain food samples were purchased from retail outlets in the summer of 1989 and surveyed for aflatoxin B1, zearalenone, and deoxynivalenol (DON [vomitoxin]) by monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Only one sample (buckwheat flour) was found to contain aflatoxin B1 (12 ng/g), whereas zearalenone was found in 26% of the samples at a mean concentration of 19 ng/g. In contrast, the DON ELISA was positive in 50% of the samples at a detection level of 1.0 micrograms/g. Between 63 and 88% of corn cereals, wheat flour/muffin mixes, rice cereals, and corn meal/muffin mixes yielded positive results for DON, whereas 25 to 50% of oat cereals, wheat- and oat-based cookies/crackers, corn chips, popcorn, and mixed-grain cereals were positive for DON. The mean DON content of the positive samples was 4.0 micrograms/g, and the minimum and maximum levels were 1.2 and 19 micrograms/g, respectively. When positive ELISA samples were also analyzed by high-performance liquid chromatography, a strong correlation between the two methods was found. The presence of DON in the two highest samples, corn meal and mixed-grain cereal, which contained 19 and 16 micrograms/g, respectively, was quantitatively confirmed by gas chromatography-mass spectrometry. The results indicated that DON was present in 1989 retail food products at concentrations that exceeded those found in previous market surveys and that have been experimentally associated with impaired animal health.     

Mycotoxins inactivation by extrusion cooking of corn flour

AIMS: To evaluate the effects of the extrusion cooking process on the inactivation of mycotoxins in corn flour. METHODS AND RESULTS: Samples of corn flour experimentally contaminated with aflatoxin B1 (AFB1) (50 ppb) and deoxynivalenol (DON) (5 ppm) were extruded. The effects of three extrusion variables (flour moisture, extrusion temperature and sodium metabisulphite addition) were analysed according to a two-level factorial design. The process was effective for the reduction of DON content (higher than 95%) under all the conditions assessed, but was only partially successful (10-25%) for the decontamination of AFB1. CONCLUSION: Extrusion cooking is effective for the inactivation of DON but is of limited value for AFB1, even if metabisulphite is added. More severe extrusion conditions are needed for the detoxification of AFB1. SIGNIFICANCE AND IMPACT OF THE STUDY: As contamination with DON occurs mainly in the field prior to harvesting and that of AFB1 is normally produced during grain storage, maize is often contaminated with DON but not with AFB1. Under these conditions, the described extrusion process can be used for the detoxification of DON. The addition of sodium metabisulphite did not significantly affect the inactivation of AFB1. Extrusion cooking is therefore an appropriate treatment for vomitoxin-contaminated maize in countries where, because of the prevailing conditions, these are the only toxins present.     

Occurrence and Distribution of Microdochium and Fusarium Species Isolated from Durum Wheat in Northern Tunisia and Detection of Mycotoxins in Naturally Infested Grain

An outbreak of Fusarium Head Blight of durum wheat occurred in 2004 being localized in sub-humid and higher semi-arid region of Northern Tunisia. A mycological survey carried out throughout these regions, revealed that 78% of the prospected fields were infested. Results of the morphological and molecular identification, showed that the most common species isolated from diseased wheat spikes was Microdochium nivale var. nivale (63.5%), followed by Fusarium culmorum (26%), F. pseudograminearum (9%) and F. avenaceum (1.5%). To evaluate mycotoxin content of naturally infected grain, the amounts of trichothecene mycotoxin deoxynivalenol (DON) in harvested grain from 45 fields were quantified by RIDASCREEN DON Enzyme Immunoassay Kit (ELISA) . This study showed that the infection levels in freshly harvested grain were very low and the maximum deoxynivalenol (DON) level of the positive samples was 53 ppb. This is the first report on the natural occurrence of DON in naturally infected wheat grain sampled from Northern Tunisia.     

Influence of instar and commodity on insecticidal effect of two diatomaceous earth formulations against larvae of Ephestia kuehniella (Lepidoptera: Pyralidae)

Laboratory experiments were carried out to evaluate the insecticidal effect of two diatomaceous earth (DE) formulations, SilicoSec and PyriSec, against larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Three instars were tested: first, third and fifth. The test was conducted in six commodities: barley Hordeum vulgare (L.) (Gramminae), rye Secale cereale L. (Gramminae), wheat Triticum sp. (Gramminae), wheat + 10% cracked wheat, wheat + 30% cracked wheat, and wheat flour. Quantities of these commodities were treated with the DEs at three dose rates: 250, 500, and 1000 ppm. Mortality of the exposed larvae on the DE-treated commodities was measured after 7 d of exposure. For both Des, mortality increased with dose, but this increase was lower when dose was increased from 500 to 1,000 ppm. The type of the commodity significantly affected DE effectiveness. Both DEs were equally effective on barley, rye, and wheat, whereas the presence of cracked wheat reduced larval mortality. In addition, significantly fewer larvae were dead on treated flour compared with the other five commodities. The increase of larval age significantly affected DE effectiveness. First instars were very susceptible to both DEs, and mortality with 1,000 ppm exceeded 86%. In contrast, fifth instar were the least susceptible to DEs, because mortality with 1000 ppm was < 22%.     

Effect of Ozone Treatment on Deoxynivalenol and Wheat Quality

Deoxynivalenol (DON) is a secondary metabolite produced by Fusarium fungi, which is found in a wide range of agricultural products, especially in wheat, barley, oat and corn. In this study, the distribution of DON in the wheat kernel and the effect of exposure time to ozone on DON detoxification were investigated. A high concentration of toxin was found in the outer part of the kernel, and DON was injected from the outside to the inside. The degradation rates of DON were 26.40%, 39.16%, and 53.48% after the samples were exposed to 75 mg/L ozone for 30, 60, and 90 min, respectively. The effect of ozonation on wheat flour quality and nutrition was also evaluated. No significant differences (P > 0.05) were found in protein content, fatty acid value, amino acid content, starch content, carbonyl and carboxyl content, and swelling power of ozone-treated samples. Moreover, the ozone-treated samples exhibited higher tenacity and whiteness, as well as lower extensibility and yellowness. This finding indicated that ozone treatment can simultaneously reduce DON levels and improve flour quality.     

Influence of localities and winter wheat cultivars on deoxynivalenol accumulation and disease damage by <Emphasis Type="Italic">Fusarium culmorum</Emphasis>

Toxin B — trichothecene deoxynivalenol (DON) is the most frequent Fusarium mycotoxin in Fusarium head blight (FHB) disease produced by Fusarium fungi. Thirty-one samples of naturally cultivated winter wheat were collected from different localities in Slovakia and evaluated for DON content, and after an artificial inoculation twelve of winter wheat cultivars were evaluated for FHB, fusarium damaged kernels (FDK) and DON content (resistance Type I and II) during two years. Plants were inoculated at anthesis with a conidial suspension of Fusarium culmorum (W. G. Smith) Sacc. The highest mean contents of DON 1.641 ppm were found in produced potato region (PPR) and 1.654 ppm in produced sugar beet region (PSBR). A positive correlation was found between DON content and rainfall, and a negative correlation was found between content of DON and temperature. Lower positive correlations were found between the contents of DON in 2003 and 2004 in the resistance Type I and Type II in twelve artificially infected cultivars. The significant positive correlations in content of DON were found between resistance Type I and Type II in the years 2003 and 2004. The lowest content of DON was found in the cultivars Alka, Malyska and the highest one in the cultivars Vanda and Boka. The positive correlation between the content of DON and FDK (in %) in head (average 2003 and 2004 years) from artificially infected and analysed cultivars was statistically significant in both resistances Type I and Type II.     

DON- und ZEA-Gehalte in Weizen, Roggen und Gerste: Besondere Ernteermittlung

In the annual national survey (‘Besondere Ernteermittlung’) the quality of German cereals was analysed. The samples for this approach were collected from statistically selected fields. One of the analysed parameters was the content of mycotoxins. Thus, it was possible to get an area-wide survey of the content of mycotoxins under natural growing conditions. In 2003 a total number of 974 samples were analysed consisting of wheat, rye and barley samples. A special mode of choosing the wheat samples ensured also a statistically validated result for the federal states of Germany. In the year 2003 the content of the mycotoxins DON and ZEA in wheat and rye samples was lower than in 2002 referred to the median. On the other hand the frequency of detection of DON was not reduced. In barley, which was analysed for the first time in this kind of study, the level of DON was in between the levels of wheat and rye.     

Bread wheat milling behavior: effects of genetic and environmental factors,and modeling using grain mechanical resistance traits

Key message

Genetic (Pinb-D1 alleles) and environment (through vitreousness) have important effects on bread wheat milling behavior. SKCS optimal values corresponding to soft vitreous or hard mealy grains were defined to obtain the highest total flour yield.

Abstract

Near-isogenic lines of bread wheat that differ in hardness, due to distinct puroindoline-b alleles (the wild type, Pinb-D1a, or the mutated forms, Pinb-D1b or Pinb-D1d), were grown in different environments and under two nitrogen fertilization levels, to study genetic and environmental effects on milling behavior. Milling tests used a prototype mill, equipped with two break steps, one sizing step, and two reduction steps, and this enabled 21 individual or aggregated milling fractions to be collected. Four current grain characters, thousand grain weight, test weight, grain diameter, and protein content, were measured, and three characters known to influence grain mechanical resistance, NIRS hardness, SKCS hardness index, and grain vitreousness (a character affecting the grain mechanical behavior but generally not studied). As expected, the wild type or mutated forms of Pinb-D1 alleles led to contrasted milling behavior: soft genotypes produced high quantities of break flour and low quantities of reduction flour, whereas reverse quantities were observed for hard genotypes. This different milling behavior had only a moderate influence on total flour production. NIRS hardness and vitreousness were, respectively, the most important and the second most important grain characters to explain milling behavior. However, contrary to NIRS hardness, vitreousness was only involved in endosperm reduction and not in the separation between the starchy endosperm and the outer layers. The highest flour yields were obtained for SKCS values comprised between 30 and 50, which corresponded either to soft vitreous or hard mealy grains. Prediction equations were defined and showed a good accuracy estimating break and reduction flours portions, but should be used more cautiously for total flour.

     

Need to determine the relative developmental risks of Fusarium mycotoxin dexoynivalenol (DON) and Benomyl (BEN) in wheat

The wheat supply is known to have levels of deoxynivalenol (DON) from fungal infections. The fungal infections can be suppressed with benomyl (BEN). Under certain exposure laboratory conditions DON and BEN are developmental toxins. Since use of BEN may result in concurrent dietary exposure to both compounds, evaluation of the relative developmental risks is needed. The dietary NOAELs for pup decreased body weight for DON and BEN are 0.375 mg/kg/day in mice and 5 mg/kg/day in rat, respectively. Human exposure to DON can be estimated from surveys of wheat grain and finished products which gave a mean DON concentration of 0.86 ppm. The tolerance level for BEN in grain is 0.2 ppm. Presence of DON and BEN in wheat at these concentrations would not impact wheat consumption. A modified margin of exposure (modMOE) was developed using “a”; kg (food) /kg (body weight) as the constant for wheat consumption. The modMOE for DON is 28/a and that for BEN is 1667/a. Comparative relative risks can be expressed as the ratio of BEN risks to DON risks (60). Treatment with BEN at the most efficacious time decreased DON levels to 34% of controls, and decreased the comparative risk ratio from 60 to 18. The potential for fungicides to decrease mycotoxin health risks is important in the safety assessment for foodstuffs. This approach improves on current practices for food safety assessment by including the expected reductions in risks from naturally occurring mycotoxins in the regulatory analysis.     

Deoxynivalenol contents in foodstuffs of organical and conventional production

Samples of wheat flour, bread, noodles, rice, corn and corn based foods as well as oats and oats based foods of conventional and organical production were analysed for trichothecene toxins. In wheat flour, bread and noodels the median deoxynivalenol (DON) contents were lower in ecological than in conventional products with significant differences for what flour and bread. To estimate toxin uptake of the consumer a corrected mean of DON concentration was calculated, which was lower in wheat flour and bread for ecological than for conventional products. In noodles the corrected mean of organical products was higher than that of conventional ones.     

The distribution of sulfur among various components of the wheat grain

Summary 1. Radioactive sulfur (S³⁵) was introduced into 3 sets of wheat plants grown hydroponically in the greenhouse. When mature, the grain was milled using micromilling procedures.2. Because of the small quantity of samples obtained, a method was developed for concentrating small amounts of sulfate.3. The highest concentration of S³⁵ in the mechanically separated fractions was in the germ, with bran, flour (endosperm), shorts, and red dog containing lesser amounts in that order.4. Radioactivity was approximately the same in the total water-soluble and gluten fractions of flour, although the percentage of nitrogen of total water-solubles was less than gluten.5. Only small differences in count rate were found between the gluten and the water-soluble proteins of the flour, indicating that much of the sulfur radioactivity in the total water-solubles was due to material other than protein.6. S³⁵ in the crude starch was almost completely in the tailings fraction.7. Gliadin was compared with glutenin and found to be somewhat higher in count rate, although nitrogen percentages of both were approximately the same.Contribution No. 538, Department of Botany and Plant Pathology; Kansas Agricultural Experiment Station, Kansas State University, Manhattan. Botany Department serial No. 694.Portion of a dissertation presented as partial fulfillment of the requirement for the Doctor of Philosophy degree in the Department of Botany and Plant Pathology, Kansas State University.     

Monitoring of fusarium toxins in cereals and feed-stuffs from thuringia (1998 - 2001)

From 1998 to 2001 a total of about 1172 conventionally and organically produced samples of wheat, rye, barley and triticale were examined for the presence of deoxynivalenol (DON) and zearalenone (ZON). Furthermore, feedstuffs for pigs were included in the monitoring of Fusarium toxins. DON and ZON analyses were performed using ELISA or HPLC. The incidences and levels of toxins varied from year to year. Overall contamination levels were highest in wheat and triticale, followed by rye and barley. The highest DON contaminations were found in 1998. The probes of the years 1999-2001 showed lower incidences of Fusarium toxins. The second examined mycotoxin ZON was detected at lower levels in cereals. Similar results were observed in the monitoring of feedstuffs.