Silvia Liliana Resnik

Mycotoxins in Latin America and the Caribbean

Abstract Mycotoxin contamination in Latin America and the Caribbean of a wide range of raw materials, foods and feeds were reviewed. Associated problems with their control were also detailed. The present regulation and prevention measures being carried out in the various countries are summarized.

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.

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 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.

Deoxynivalenol and contaminant mycoflora in freshly harvested Argentinian wheat in 1993

A mycological survey was carried out on wheat heads from the main production area of Argentina. The isolation frequency and relative density of species from genus Fusarium and dematiaceous fungi were calculated. F graminearum was the predominant Fusarium species; similar to that observed in the USA and Canada. An analysis of deoxynivalenol (DON) natural contamination also was performed on a limited number (44) of samples. DON contamination levels in positive samples ranged from 0.2 to 30 ppm. A stepwise regression procedure showed that, among the species analysed, F. graminearum relative density was related to the DON contamination level and that other prevalent fungi did not influence or modify that relationship.

Study of mathematical models applied to sorption isotherms of Argentinean black bean varieties

Abstract Moisture sorption isotherms of five commercial black bean varieties harvested in the province of Salta, Argentina, were measured. Statistical methodology was applied to compare their sorption characteristics and it was observed that the five varieties could be considered as belonging to a same group. Different equations proposed in the literature were studied and it was found that the best adjustments were provided by the Oswin and the White and Eiring equations. The estimated isotherm equations are given. Adjusting the equations to sorption data found in literature, the White and Eiring equation provided a reasonable adjustment for all of them.

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.

Trichothecenes and zearalenone production by fusarium species isolated from Argentinean black beans.

Isolates of Fusarium species obtained from freshly harvested bean grains for human consumption collected from different Argentinean regions, were investigated for their ability to biosynthesise trichothecenes and zearalenone either on rice grains or beans. Low incidence of toxigenic fungi was observed. These mycotoxigenic species produced several toxins when grown on rice but none or little amount when cultured on beans. The results of this report suggest that contamination of Argentinean beans with Fusarium mycotoxins will not be common and therefore people would be at low mycotoxicosis risk through consumption of beans.

Mycotoxigenic potential of fungi isolated from freshly harvested Argentinean blueberries

Alternaria alternata, A. tenuissima, Fusarium graminearum, F. semitectum, F. verticillioides, Aspergillus flavus, and Aspergillus section Nigri strains obtained from blueberries during the 2009 and 2010 harvest season from Entre Ríos, Argentina were analyzed to determine their mycotoxigenic potential. Taxonomy status at the specific level was determined both on morphological and molecular grounds. Alternariol (AOH), alternariol monomethyl ether (AME), aflatoxins (AFs), zearalenone (ZEA), fumonisins (FBs), and ochratoxin A (OTA) were analyzed by HPLC and the trichotecenes deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin (HT-2), T-2 toxin (T-2), fusarenone X (FUS-X), 3-acetyl-deoxynivalenol (3-AcDON), and 15-acetyl-deoxynivalenol (15-AcDON) by GC. Twenty-five out of forty two strains were able to produce some of the mycotoxins analyzed. Fifteen strains of Aspergillus section Nigri were capable of producing Fumonisin B1 (FB1); two of them also produced Fumonisin B2 (FB2) and one Fumonisin B3 (FB3). One of the F. graminearum isolated produced ZEA, HT-2, and T-2 and the other one was capable of producing ZEA and DON. Two A. alternata isolates produced AOH and AME. Four A. tenuissima were capable of producing AOH and three of them produced AME as well. One Aspergillu flavus strain produced aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), and aflatoxin G1 (AFG1). To our knowledge, this is the first report showing mycotoxigenic capacity of fungal species isolated from blueberries that include other fungi than Alternaria spp.

Reduction of Mycotoxin Contamination by Segregation with Sieves Prior to Maize Milling

The strategies for reducing mycotoxin concentrations in maize are currently under development. Some approaches are directed toward resistance to infection or infection reduction in the grain, whereas others are aimed at detoxification of contaminated maize. To diminish contamination by natural mycotoxins, there are some strategies which imply grain handling.