Elena J. Martínez

The effects of bakery processing on natural deoxynivalenol contamination

The aim of this study was the evaluation of the influence of the breadmaking process on initial deoxynivalenol (DON) contamination. Samples (92) were taken from four batches of eight different types of products in a low-technology bakery. The final products, as well as the corresponding flours, doughs and fermented doughs were analyzed. Extracts were obtained with acetonitrile:water (84:16), the clean up was made with a multifunctional column and DON was quantified by thin layer chromatography by visual comparison with standards. Confirmation was made by electron capture gas chromatography. The contamination levels in flour samples ranged from 500 micrograms/kg to 2000 micrograms/kg on dry weight basis. The results showed a positive correlation between the initial contamination level and the reduction of DON after fermentation. A significant reduction was observed as a consequence of the breadmaking process.

Natural co-occurrence of fumonisins, deoxynivalenol, zearalenone and aflatoxins in field trial corn in Argentina.

Corn samples collected from the main production area in Argentina in 1995 were surveyed for the natural occurrence of Fusarium mycotoxins and aflatoxins. Fumonisins B1, B2 and B3 and zearalenone were found in all samples. A positive relationship was found between fumonisins B1, B2 and B3, B1 and B3, and B2 and B3. Deoxynivalenol and aflatoxins were not detected. Mycological survey has also revealed the predominance of Fusarium moniliforme. This is the first report on the simultaneous occurrence of fumonisins and zearalenone in corn from the main production area in Argentina.

Relationship between Fusarium graminearum and Alternaria alternata contamination and deoxynivalenol occurrence on Argentinian durum wheat

A mycological survey was carried out on durum wheat (Triticum durum) samples from the main production area of Argentina. The isolation frequency and relative density of species of dematiaceous fungi, and genus Fusarium were calculated. Alternaria alternata and Fusarium graminearum were the predominant fungal species. An analysis of deoxynivalenol (DON) natural contamination was also performed on a limited number of samples (60). DON contamination levels in positive samples ranged from 26 to 6400 μg/kg. The non-parametric techniques applied showed that there is a positive relationship between DON contamination and F. graminearum relative densities and a negative relationship between DON contamination and A. alternata relative densities.

Natural occurrence of deoxynivalenol in wheat, wheat flour and bakery products in Argentina.

The objective of this study was to evaluate the natural occurrence of deoxynivalenol (DON) in wheat, wheat flour and different kinds of breads and pastries widely consumed by the population in Argentina. Of 60 wheat samples analysed, 93.3% were contaminated. The average DON contamination level over all samples was 1798 micrograms/kg, and the minimum and maximum values were 100 micrograms/kg and 9250 micrograms/kg, respectively. The wheat flour samples (61 samples) were contaminated with DON at levels ranging from 250 micrograms/kg to 9000 micrograms/kg with an average of 1309 micrograms/kg. The frequency of DON contamination over 42 samples of different bakery products was 92.8%, with levels ranging from 200 micrograms/kg to 2800 micrograms/kg with an average of 464 micrograms/kg. These results suggest a high risk for consumers of wheat products and the need to monitor final products before consumption.

Occurrence of trichothecenes in Argentinean beer: a preliminary exposure assessment.

The presence of trichothecenes (deoxynivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, nivalenol, neosolaniol and diacetoxyscirpenol) was studied in 50 samples of Argentinean beer (nine different brands). Gas chromatography with electron capture detector was used for identification and quantification of these mycotoxins. The only mycotoxin detected was deoxynivalenol (DON). It was present in 44% of the samples, 18% were contaminated with more than 20ng/ml. Toxin levels ranged from 4 to 221ng/ml in positive samples. This is the first report on DON contamination of Argentinean beer. The estimate of probable daily intake (PDI) of DON from beer consumption in Argentina does not indicate a health hazard, but it has to be taken into account in calculations of total DON exposure in the population.

Natural occurrence of trichothecenes and zearalenone in Argentine wheat

Abstract A survey of the natural occurrence of trichothecenes and zearalenone in samples from Buenos Aires and Santa Fe provinces, Argentina, was carried out in six different crops during harvest. Among 1056 samples analysed, 524 (49.62%) were contaminated with trichothecenes and zearalenone. Deoxynivalenol was detected in all of the contaminated samples, 3-Acetyl DON in 22 samples and zearalenone in 78. In 1986, T-2 toxin (20 samples), HT-2 toxin (18), neosolaniol (16) and diacetoxyscirpenol (26) were also found. The results suggest that when meteorological conditions favour contamination it is necessary to carry out strict controls on harvest time.

Sorption isotherms of corn—Study of mathematical models

In this paper statistical methodology is used to determine similar groups of Argentine maize varieties and to model the behaviour of the moisture content as a function of the water activity. Different equations proposed in the literature are studied and a common mathematical model is obtained for all varieties whatever the adequacy criteria considered. The use of the goodness of fit criteria is also discussed.

Fungal and fumonisins contamination in Argentine maize (Zea mays L.) silo bags.

Fumonisins in maize (Zea mays L.) grain silo bags in the conditions of three Argentine provinces were analyzed to determine how this kind of storage affects contamination and if differential storage durations or times of the year of silo bag closing and opening are factors that could modify it. Moisture content, water activity (a(w)), molds and yeasts present, and fumonisins were analyzed in 163 maize silo bags, at the moment of closing and later at opening. Storage durations ranged from 120 to 226 days. The analysis was centered on fumonisins since most samples were only contaminated with these toxins. Fumonisins, moisture content, and a(w) increased significantly, whereas mold propagules/g and yeasts CFU/g did not present significant differences between silo opening and closing. The date on which silo bags were closed and later opened, however, did affect the level of fumonisin contamination.

Robust testing in the logistic regression model

We are interested in testing hypotheses that concern the parameter of a logistic regression model. A robust Wald-type test based on a weighted Bianco and Yohai [ Bianco, A.M., Yohai, V.J., 1996. Robust estimation in the logistic regression model. In: H. Rieder (Ed) Robust Statistics, Data Analysis, and Computer Intensive Methods In: Lecture Notes in Statistics, vol. 109, Springer Verlag, New York, pp. 17-34] estimator, as implemented by Croux and Haesbroeck [Croux, C., Haesbroeck, G., 2003. Implementing the Bianco and Yohai estimator for logistic regression. Computational Statististics and Data Analysis 44, 273-295], is proposed. The asymptotic distribution of the test statistic is derived. We carry out an empirical study to get a further insight into the stability of the p-value. Finally, a Monte Carlo study is performed to investigate the stability of both the level and the power of the test, for different choices of the weight function.

Robust Estimation in Vector Autoregressive Moving‐Average Models

Bustos and Yohai proposed a class of robust estimates for autoregressive moving-average (ARMA) models based on residual autocovariances (RA estimates). In this paper an affine equivariant generalization of the RA estimates for vector ARMA processes is given. These estimates are asymptotically normal and, when the innovations have an elliptical distribution, their asymptotic covariance matrix differs only by a scalar factor from the covariance matrix corresponding to the maximum likelihood estimate. A Monte Carlo study confirms that the RA estimates are efficient under normal errors and robust when the sample contains outliers. A robust multivariate goodness-of-fit test based on the RA estimates is also obtained.