Concentrations and exposure estimates of deoxynivalenol in wheat products from Argentina.

The aim of this work was to determine deoxynivalenol (DON) contamination in wheat-based food products in Argentina and to estimate DON exposure. The numbers of samples were determined according to a developed sampling plan. A total of 156 samples of different wheat products were randomly collected from food markets in Luján, Argentina, and analyzed for DON by gas chromatography. DON contamination ranged 7-271 ng g(-1) for French bread, 5-149 ng g(-1) for Vienna bread, 11-85 ng g(-1) for crackers, 8-85 ng g(-1) for pizza, and was 79 ng g(-1) for noodles. The maximum contribution to DON intake was 7% of the PMTDI for French bread; the minimum was less than 1% for noodles. Assuming all groups had eaten all sampled foods and summing all groups' intake contribution, the highest estimate DON exposure would only be <14% (for the 18-24-year old men group) of the DON daily dietary intake.

Survey of Argentinean human plasma for ochratoxin A.

The presence of ochratoxin A (OTA) in human blood has been reported for many countries, especially in Europe. However, so far no report exists concerning such a presence in Argentina. The aim of this study was to assess OTA concentration in human plasma in two different areas of Buenos Aires province. OTA was determined by high-performance liquid chromatography (HPLC) in 199 plasma samples from blood donors in Mar del Plata and 236 from General Rodriguez. Solid-phase extraction with Bakerbond C-18 cartridge and a final purification with Ochraprep immunoaffinity columns was employed. The limit of quantification of ochratoxin A was 0.019ngml(-1) and the confirmation of OTA was by formation of ochratoxin A methyl ester. The results showed that 63.8% of human plasma samples from Mar del Plata and 62.3% from General Rodriguez were positive for OTA, with Winsorized means of 0.15 and 0.43ngml(-1), respectively. It is important to continue the research to detect the foods responsible of the presence of OTA in plasma.

Trichothecenes and mycoflora in wheat harvested in nine locations in Buenos Aires province, Argentina.

A total of 120 freshly harvested wheat samples from the 2004 season in nine locations from Northern Buenos Aires Province, Argentina, were analysed for trichothecene natural occurrence and associated mycoflora, and for determining the influence of commonly used fungicide field treatment and the cultivar type on trichothecene contamination. The trichothecenes T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), diacetoxyscirpenol (DAS), nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) were analysed by gas chromatography and electron capture detection. Detection limits ranged from 4 to 20 microg/kg. The isolation frequencies of species were calculated. Alternaria alternata, Fusarium graminearum, Fusarium poae and Fusarium semitectum were the predominant fungal species identified as endogenous mycoflora. The type of cultivar and the fungicide field treatment did not affect significantly the trichothecene contamination. The trichothecenes type A detected were HT-2 and T-2 triol toxins and the type B were DON, NIV and 3-ADON. Based on 120 samples the incidences were 21.7% for 3-ADON, 22.5% for HT-2, 27.5% for T-2 triol and 85% for DON. NIV was confirmed in one sample. Mean levels of trichothecene positive samples were between 7 and 2788 microg/kg.

In vitro effect of phenolic antioxidants on germination, growth and aflatoxin B accumulation by peanut Aspergillus section Flavi.

AIMS: The effectiveness of the food-grade antioxidants butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB), propyl paraben (PP) and butylated hydroxyanisole (BHA) at 1, 10 and 20 mmol l(-1) concentrations on germination, growth, and aflatoxin B(1) (AFB(1)) production by Aspergillus section Flavi strains was determined. METHODS AND RESULTS: Assays on the lag phase of germination, germination percentage, germ tube elongation rate, lag phase, growth rate and AFB(1) production by three strains of Aspergillus flavus and three of Aspergillus parasiticus were carried out in vitro on peanut extract meal agar conditioned at different water activities (a(w): 0.982, 0.971, 0.955, 0.937). The antioxidants PP and BHA efficiently inhibited the germination of the two species tested at the doses 10 and 20 mmol(-1). The antioxidants PP and BHA at 1 mmol l(-1) and THB at 20 mmol l(-1) reduced the germ tube elongation rate most effectively, regardless of a(w) levels. An increase in the lag time and a reduction in the growth rate of 100% of the strains was observed, this was due to the action of BHT at the doses 10 and 20 mmol(-1) at 0.982, 0.971 and 0.955 a(w), although these treatments stimulated the AFB(1) accumulation in most of the fungi tested. The more effective antioxidants were PP and BHA, which increased the lag phase, reduced the growth rate and AFB(1) production in all of the strains at the four a(w) assayed. At concentrations 10 and 20 mmol l(-1), these antioxidants totally inhibited fungal development. CONCLUSIONS: The study shows that the antioxidants BHA and PP are effective fungal inhibitors to peanut Aspergillus section Flavi in wide range of water activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that phenolic antioxidants, BHA and PP, can be effective fungitoxicants on aflatoxigenic strains in peanut at industrial level.

Mycoflora and potential for mycotoxin production of freshly harvested black bean from the Argentinean main production area.

A mycological survey was carried out, for the first time, on black bean samples from the northwestern Argentinean province of Salta in the 1999 harvest season. Ten varieties of black beans were evaluated at three locations. Species of the genus Alternaria were the most prevalent component of the black bean mycoflora. Species of Fusarium, Sclerotinia, Rhizoctonia and Acremonium were also recorded. The predominant species of the genera isolated were Alternaria alternata, Sclerotinia sclerotiorum, Rhizoctonia solani, Fusarium semitectum and Acremonium strictum. An analysis of variance was applied to determine possible differences between black bean varieties. Variety FT88/519 was the most susceptible to Sclerotinia sclerotinia infection, while the variety DOR 604 was the least susceptible. As toxigenic species were recovered, Alternaria toxins, zearalenone and trichothecenes may pose a contamination risk for black bean.

Fungi associated with food and feed commodities from Ecuador.

Freshly harvested soybean, rice and corn from farms and corn-based pelleted feeds were collected from ranches from the coastal and mountain regions in Ecuador during 1998, and assessed for fungal contamination. The most prevalent fungi on pelleted feed were Aspergillus flavus and Fusarium graminearum. The prevalent fungi recovered from soybean were F. verticillioides, F. semitectum, Aspergillus flavus and A. ochraceus. In rice, F. oxysporum was the most prevalent toxigenic fungal species recorded, followed by F. verticillioides and A. flavus. In corn, F. verticillioides was the most prevalent fungus isolated in both the coastal and mountain regions, with high isolation frequencies of A. flavus and A. parasiticus at the coast. Based on the toxigenic species recovered, ochratoxin A may pose a contamination risk for soybean. A higher probability of aflatoxin contamination of corn was found in the coastal samples compared to those of the mountain region, while a risk of fumonisin contamination of corn exists in both regions.

Distribution of fumonisins in dry-milled corn fractions in Argentina.

Corn samples and different dry-milled fractions collected from an industrial mill in Argentina were analysed. Average contaminations were FB(1) 1540 microg kg(-1), FB(2) 716 microg kg(-1) and FB(3) 152 microg kg(-1) in whole corn; FB(1) 135 microg kg(-1), FB(2) 39.1 microg kg(-1) and FB(3) 10.2 microg kg(-1) in corn grits; FB(1) 358 microg kg(-1), FB(2) 122 microg kg(-1) and FB(3) 45.9 microg kg(-1) in 'C' flour; FB(1) 148 microg kg(-1), FB(2) 52.5 microg kg(-1) and FB(3) 28.3 microg kg(-1) in corn meal; and FB(1) 4210 microg kg(-1), FB(2) 2010 microg kg(-1) and FB(3) 447 microg kg(-1) in germ and bran together. The fumonisin contamination level was approximately three times higher in germ and bran than in whole corn, 13 times higher than in 'C' flour and 29 times higher than in corn meal and corn grits. Taking into account the distribution of fumonisins in commercial dry-milled corn fractions and corn meal consumption in Argentina, a theoretical whole corn level of 6640 microg kg(-1) maximum of total fumonisins could be processed to obtain products considered safe for human health.

Natural occurrence of mycotoxins and mycoflora of argentinien popcorn.

Argentina is the first popcorn exporting country worldwide. In 1997-1998 harvest season, 40,000 ha were sown with a production of 125,000 tons; 120,000 tons of this production were exported to more than 40 countries. The objectives of this study were to isolate and to identify the fungi present in this cereal and to assess the occurrence of mycotoxins in freshly harvested popcorn in Buenos Aires province, Argentina, in 1999. All popcorn samples showed fungal contamination. A total of 4,211 isolates were recovered from popcorn kernel samples. The prevalent species isolated wasFusarium verticillioides followed byPenicillium funiculosum, F. graminearum andAlternaria alternata. No aflatoxins, zearalenone, deoxynivalenol or ochratoxin A were detected in the 42 popcorn simples. All samples but one were contaminated with fumonisins (FB) in a range in ug/kg of (not detected-529) for FB1; (not detected-216) for FB2 and (not detected-103) for FB3. Fumonisin contamination levels in Argentinean popcorn were lower than observed in flint corn. No significant differences in fungal and fumonisins contamination levels were observed in the different tested hybrids.

Mycoflora of freshly harvested flint corn from Northwestern Provinces in Argentina.

A mycological survey was carried out for the first time, on red flint corn samples from the northwestern Andinian region of Argentina in the 1999 and 2000 harvest seasons. Species of the genus Fusarium were the most prevalent component of the flint corn mycoflora present in all provinces. F. verticillioides was the predominant Fusarium isolated in the 1999 harvest season in the the region, and was found at higher incidence level than those observed on commercial semident corn hybrids harvested in the main corn production area in Argentina (Pampean region). During the 2000 harvest season, Fusarium graminearum was most commonly isolated species in Salta province.

Effect of fermentation on naturally occurring deoxynivalenol (DON) in Argentinean bread processing technology.

The stability of naturally occurring DON was evaluated during the fermentation stage of the bread-making process on a pilot scale. Two different products, French bread and Vienna bread, were prepared with naturally contaminated wheat flour (150 mg kg(-1)) under controlled experimental conditions. Dough was fermented at 30, 40 and 50 degrees C according to standard procedures employed in Argentinean low-technology bakeries. When the dough was fermented at 50 degrees C, the maximum reduction was 56% for the Vienna bread, with French bread being reduced by 41%. DON reduction during bread-making occurs not only in the baker due to thermal decomposition, but also during the fermentation step. The Argentinean traditional bread-making process might reduce DON levels during the fermentation stages if the dough is leavened at temperatures > 30 degrees C.

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.

Production of alternariol and alternariol mono-methyl ether by isolates of Alternaria spp. from Argentinian maize.

Alternaria cultures (87 isolates of Alternaria alternata, four of A. tenuissima, two of A. radicina, and three of Alternaria state of Pleospora infectoria respectively, from maize) were screened to determine their ability to produce alternariol (AOH) and alternariol monomethyl ether (AME) on maize and rice. Only 28 A. alternata stains had toxigenic capacity. When maize was used as substrate 21 of 28 isolates produced AOH and AME, and 23 of 28 strains produced AOH and 22 of 28 produced AME when rice was used. The level of AOH produced by the isolates ranged from 0.3 to 2.1 mg/kg on maize and from 0.4 to 9.9 mg/kg on rice. The AME production by the stains ranged between 0.3 and 3.3 mg/kg both on maize and on rice. These results could indicate a low probability of AOH and AME occurring naturally on maize 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 micrograms/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.

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 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.

Production of trichothecenes and zearalenone by isolates of Fusarium spp. from Argentinian maize.

Fusarium cultures (27 isolates of Fusarium graminearum, 5 of F. sporotrichioides, 5 of F. semitectum, 2 of F. solani, and one isolate of F. equiseti, F. heterosporum and F. oxysporum respectively, from maize ears) were screened to determine their ability to produce different trichothecenes and zearalenone. Twenty of 27 F. graminearum isolates produced deoxynivalenol (384-5745 micrograms/kg), 7/27 produced 3-acetyl-deoxynivalenol (322-1840 micrograms/kg), 3/27 produced neosolaniol (199-898 micrograms/kg), 5/27 produced diacetoxyscirpenol (205-3095 micrograms/kg), 4/27 produced HT-2 toxin (278-1377 micrograms/kg) and 13/27 produced zearalenone (200-35045 micrograms/kg). No isolate of F. graminearum produced either nivalenol, 15-acetyl-deoxynivalenol, T-2 tosin, T-2 triol or T-2 tetraol. Only chemotype IA (deoxynivalenol and 3-acetyl-deoxynivalenol) was observed. F. sporotrichioides isolates produced deoxynivalenol (5/5), T-2 triol and T-2 tetraol (1/5) and zearalenone (1/5). One F. semitectum isolate produced diacetoxyscirpenol and F. equiseti and F. oxysporum isolates produced only deoxynivalenol. Thus, three of the toxins studied, deoxynivalenol, zearalenone and 3-acetyl-deoxynivalenol are most likely to appear as contaminants in freshly harvested maize.

Fungi associated with sorghum grain from Argentina.

Sorghum (Sorghum bicolor (L.) Moench) is an important cereal produced in and exported from Argentina. The risk of contamination by mycotoxins is related to the mycoflora associated with the sorghum grain. This paper reports on the identification of internal mycoflora of sorghum grain harvested in Argentina in 1991, 1992 and 1993, years with different total rainfall levels. A mycological survey was carried out on sorghum samples, from a location at the humid Argentinian pampa, using a Fusarium/dematiaceous fungi selective medium. The relative density of the prevalent fungal genera were statistically compared. Genus Fusarium was the most prevalent component of the internal seedborne mycoflora in the three harvest seasons. Genera Alternaria, Phoma, Penicillium and Aspergillus were also isolated. The predominant Fusarium was F. moniliforme and the most frequently isolated species of Alternaria, Phoma, Penicillium and Aspergillus were Alt. alternata. Pho. sorghima, Pen. funiculosum and Asp. flavus, respectively. This is the first report of the isolation of Fusarium napiforme in sorghum grain in Argentina.

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.

Moniliformin production byFusarium species isolated from Argentinian corn.

Forty-one isolates ofFusarium obtained from the main Argentinian corn production area were tested for their ability to produce moniliformin. One of 22 isolates ofF. moniliforme, 2/10 of F.proliferatum and 3/9 ofF. subglutinans, produced moniliformin in a range between 0,3 to 2,7 mg/g. These data represent the first report of the production of moniliformin byFusarium species from section Liseola in Argentina.

Cyclopiazonic acid and aflatoxins production byAspergillus flavus isolated from Argentinian corn.

Thirty-four isolates ofAspergillus flavus obtained from the main Argentinian corn production area were tested for their ability to produce both cyclopiazonic acid (CPA) on corn and on liquid media and aflatoxins on corn.Aflatoxins and CPA were quantified by comparison with standards. The last one was confirmed by mass spectrometry.All but one of the isolates produced CPA on liquid medium in a range between 3120 to 62500 µg/kg, 27/34 isolates produced CPA on corn at levels ranging from 833 to 10000 µg/kg and 5/34 isolates produced aflatoxin B1 in a range between 29 to 115 µg/kg. According to these findings, the percentage ofAspergillus flavus isolates with CPA production ability and their levels of CPA production were higher than the observed elsewhere.It was observed significant differences (p<0,01) between CPA production on corn (median: 1761 µg/Kg) and in liquid medium (median: 27950 µg/Kg). These data represent the first report of the co-production of CPA and aflatoxin B1 by isolates ofAspergillus flavus obtained from corn in Argentina.