Aflatoxins (AFs) are secondary metabolites produced by Aspergillus section Flavi during their development, particularly in maize. It is widely accepted that AFB1 is a major contaminant in regions where hot climate conditions favor the development of aflatoxigenic species. Global warming could lead to the appearance of AFs in maize produced in Europe. This was the case in 2015, in France, when the exceptionally hot and dry climatic conditions were favorable for AF production. Our survey revealed AF contamination of 6% (n = 114) of maize field samples and of 15% (n = 81) of maize silo samples analyzed. To understand the origin of the contamination, we characterized the mycoflora in contaminated samples and in samples produced in the same geographic and climatic conditions but with no AFs. A special focus was placed on Aspergillus section Flavi. A total of 67 strains of Aspergillus section Flavi were isolated from the samples. As expected, the strains were observed in all AF+ samples and, remarkably, also in almost 40% of AF− samples, demonstrating the presence of these potent toxin producers in fields in France. A. flavus was the most frequent species of the section Flavi (69% of the strains). But surprisingly, A. parasiticus was also a frequent contaminant (28% of the strains), mostly isolated from AF+ samples. This finding is in agreement with the presence of AFG in most of those samples.

Ergot is a disease of cereals and grasses caused by the ascomycete fungusClaviceps purpurea (Fr.) Tul. This fungus infects young, usually unfertilised ovaries, replacing the seeds with dark mycelial masses known as sclerotia. The amount of sclerotia in marketable grain is strictly regulated in many countries. We found that ergot and its alkaloids were common in French farm fields during the 2012, 2013 and 2014 harvests. Before cleaning, ergot was present in harvest samples from 23 to 30% of wheat fields, 15 to 30% of durum wheat fields, 27 to 39% of barley fields, 45 to 66% of triticale fields, 12 to 29% of oat fields and 67 to 81% of rye fields. Triticale and rye were thus the cereals most prone to infection. The proportion of total ergot alkaloid in sclerotia varied, but the relationship between ergot sclerotium content and total ergot alkaloid concentration in the grain was strongly positive and independent of harvest year and cereal species. Ergot sclerotia content explained 75% of the variance for alkaloid content. We found that the main alkaloid and corresponding epimer, per gram of sclerotia, were ergotamine (29.2% of total ergot alkaloids), followed by ergosine (26.3%), ergocristine (18.5%), ergometrine (9.8%), ergocryptine (8.2%) and ergocornine (7.9%). The -ine isomers accounted for 70.5%, with the -inine isomers accounting for the remaining 29.5%. The mean total alkaloid content ofC. purpurea sclerotia was 3,103 µg/g. This survey identified and ranked agronomic practices for limiting the risk of ergot contamination in crops. Host plant, previous crop, grassweed presence and tillage system all had a significant influence on alkaloid content. We identified and ranked agronomic practices for limiting and managing the risks of ergot and ergot alkaloids in the field. However, the main factor driving ergot infection is weather conditions.

Aflatoxins are carcinogenic mycotoxins that may contaminate many crops and more especially maize. To protect consumers from these contaminants, many countries set up low regulatory thresholds of few µg/kg. The control of food requires time-consuming analysis for which sampling is a key step. It would therefore of key sanitary and economic relevance to develop rapid, sensitive and accurate methods that could even be applied on line at harvest, to identify batches to be excluded as soon as possible. In this study, we analyzed more than 500 maize samples taken at harvest during 3 years for their aflatoxin contamination using HPLC-MS. Among them, only 7% were contaminated but sometimes at levels largely exceeding European regulations. We demonstrate that Near InfraRed Spectroscopy (NIRS) could be of great help to classify cereal samples according to their level of aflatoxin contamination (below or higher than E.U. regulation). To build the model, all AF contaminated samples as well as an equivalent number of AF free samples were used. NIRS performance was not sufficient to quantify the toxins with adequate precision. However, its ability to discriminate naturally contaminated maize samples according to their level of contamination with aflatoxins in relation to European regulations using a quadratic PCA-DA model was excellent. Accuracy of the model was 97.4% for aflatoxin B1 and 100% for total aflatoxins.

The objective of this study is to assess near-infrared (NIR) hyperspectral imaging for the detection of ergot bodies at the particle level in cereal flour. For this study, ground ergot body samples and wheat flour samples as well as mixtures of both from 100 to 500,000 mg kg^–1 were analysed. Partial least squares discriminant analysis (PLS-DA) models were developed and applied to spectral images in order to detect the ergot body particles. Ergot was detected in 100% of samples spiked at more than 10,000 mg kg^–1 and no false-positives were obtained with non-contaminated samples. A correlation of 0.99 was calculated between the reference values and the values predicted by the PLS-DA model. For the cereal flours containing less than 10,000 mg kg^–1 of ergot, it was possible for some samples spiked as low as 100 mg kg^–1 to detect enough pixels of ergot to conclude that the sample was contaminated. However, some samples were under- or overestimated, which can be explained by the lack of homogeneity in relation to the sampling issue and the thickness of the sample. This study has demonstrated the potential of NIR hyperspectral imaging combined with chemometrics as an alternative solution for discriminating ergot body particles from cereal flour.

The European Commission has considered the appropriateness of setting a maximum level for T-2 and HT-2 toxins in cereals and cereal products in future. Occurrence studies show that oats, and to a lesser extent barley, seem to accumulate higher levels of these toxins than other cereals. Consequently, ARVALIS – Institut du végétal has conducted a field survey in collaboration with different French partners (cooperatives and merchants, agro industries and research institutes). The agronomic factors identified to reduce the risk of T-2 and HT-2 toxins on barley are different from those identified for deoxynivalenol (DON). They are, in decreasing order of importance: sowing date, rotation (number of small grain cereals in the last 2 years), tillage (with a smaller impact than for DON), and possibly varietal susceptibility and fungicide protection. Finally, this field survey shows that DON, and T-2 and HT-2 toxins seem to be opposed, which probably means a different risk management for these different mycotoxins.