Thalita Calado

Irradiation for Mold and Mycotoxin Control: A Review

The mycotoxin issue requires constant vigilance from economic, regulatory, and scientific agents to minimize its toxicological effects on human and animals. The implementation of good practices to avoid fungal growth and mycotoxin production on agricultural commodities is essential to achieve most restrictive safety standards; however, the contribution of novel technologies that may act on postharvesting and poststorage situations may be equally important. Several methodologies, more or less technologically advanced, may be used for this purpose. In this work, we review the role, contribution, and impact of irradiation technology to control the presence of fungi and mycotoxins in food and in feed. The effect of this technology on the viability of mold spores and on the elimination of mycotoxins is reviewed. A critical evaluation of the advantages and disadvantages of irradiation in this context is presented.

A Review of Mycotoxins in Food and Feed Products in Portugal and Estimation of Probable Daily Intakes

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that occur naturally in agricultural commodities worldwide. Aflatoxins, ochratoxin A, patulin, fumonisins, zearalenone, trichothecenes, and ergot alkaloids are presently the most important for food and feed safety. These compounds are produced by several species that belong to the Aspergillus, Penicillium, Fusarium, and Claviceps genera and can be carcinogenic, mutagenic, teratogenic, cytotoxic, neurotoxic, nephrotoxic, estrogenic, and immunosuppressant. Human and animal exposure to mycotoxins is generally assessed by taking into account data on the occurrence of mycotoxins in food and feed as well as data on the consumption patterns of the concerned population. This evaluation is crucial to support measures to reduce consumer exposure to mycotoxins. This work reviews the occurrence and levels of mycotoxins in Portuguese food and feed to provide a global overview of this issue in Portugal. With the information collected, the exposure of the Portuguese population to those mycotoxins is assessed, and the estimated dietary intakes are presented.

Incidence of Fumonisin B2 Production by Aspergillus niger in Portuguese Wine Regions

Fumonisin B(2) (FB(2)) was recently found to be produced by Aspergillus niger . When grape-derived products were subsequently analyzed, FB(2) contamination was found in raisins, must, and wine. This study evaluated 681 strains of black aspergilli species isolated from Portuguese wine grapes for FB(2) production when grown on Czapek yeast agar. FB(2) was not detected in Aspergillus carbonarius (n = 75) or Aspergillus ibericus (n = 9) strains, but it was detected in 176 (29%) of the strains belonging to A. niger aggregate (n = 597). The amount of FB(2) produced by these strains ranged from 0.003 to 6.0 mg/kg with a mean of 0.66 mg/kg. The Alentejo region had the lowest percentage (10%) of fumonisinogenic strains, whereas the Douro region had the highest percentage of fumonisinogenic strains (38%). Only 10 strains were found to produce FB(2) and ochratoxin A simultaneously.

Mycotoxin production by Aspergillus niger aggregate strains isolated from harvested maize in three Portuguese regions

BACKGROUND Maize is considered one of the crops more susceptible to mycotoxins in the world. Two of the mycotoxins commonly associated with maize are fumonisins and ochratoxin A. Aspergillus niger is a known producer of ochratoxin A and is easily found in maize. Recently, however, A. niger has been reported to produce as well fumonisins, mainly fumonisin B(2). AIMS The aim of this study was to isolate A. niger strains from maize samples collected in three Portuguese maize growing regions and to detect the production of both fumonisin B(2) and ochratoxin A. METHODS Ninety five maize samples were collected, plated, and all observable Aspergillus section Nigri strains were isolated. Strains were morphologically characterized and mycotoxin production was determined by HPLC-FD. RESULTS Isolations resulted in a total of 270 strains of black Aspergillus from 73 samples (77% of the samples). About 14% of those strains were found to produce ochratoxin A and 39% of the strains were found to produce fumonisin B(2). CONCLUSIONS An association between the production of these two mycotoxins could not be found and no conclusions could be taken whether the presence of A. niger aggregate strains will increase the risk of maize contamination with fumonisins and more specifically with fumonisin B(2).

A fluorescence-LC method with NDA pre-column derivatization for fumonisin B2 determination in black aspergilli cultures

The recent discovery that Aspergillus niger can produce fumonisins raises a new mycotoxigenic risk that requires additional studies to assess the impact on agricultural commodities. Here, we report the development and validation of a sensitive LC-fluorescence method for the identification of fumonisin B2 in black aspergilli cultures. The performances of naphthalene-2,3-dicarboxaldehyde (NDA), o-phthaldialdehyde (OPA), and 9-fluorenylmethyl chloroformate (FMOC) for the precolumn derivatization of samples were evaluated and compared. The best methodology included the following elements: NDA was used during pre-column derivatization; the derivatives were separated by a 30 min isocratic elution with acetonitrile/H2O/acetic acid (60:40:1, v/v/v), pumped at a flow rate of 1 mL · min−1 on a polar C18 reversed-phase YMC-Pack ODS-AQ column (250 × 4.6 mm, 5 µm); and fluorescence detection using excitation and emission wavelengths of 420 and 500 nm, respectively. The calibration curve was found to give a good linear response (r2 > 0.9999) from 1 to 200 µg · L−1. For FB2, which is the main fumonisin detected in black aspergilli thus far, this method measured an LOD and an LOQ of 2 and 6 µg · kg−1, respectively. Using this method, the amount of FB2 in black aspergilli cultures can be simply and rapidly determined.

Gamma irradiation effects on ochratoxin A: Degradation, cytotoxicity and application in food

Ochratoxin A (OTA) is one of the main mycotoxins that can be found in food. The use of gamma radiation is a technique for preserving food that may exert some effects on mycotoxins. OTA was irradiated in its dry form, in aqueous and in methanolic solutions, and in wheat flour, grape juice and wine. Additionally, the toxicity of OTA irradiated in water was tested. In aqueous solutions, more than 90% of the OTA was degraded by γ-radiation doses ≥2.5kGy, and a 2-fold reduction in OTA cytotoxicity was observed. In food matrices, the elimination of OTA by γ-radiation was found more difficult, as radiation doses of 30kGy eliminate at most 24% of the OTA. Higher moisture content of food matrices did not substantially increase OTA elimination. It is concluded that OTA is very sensitive to irradiation in water solutions but resistant in its dry form and in food matrices.