Reduction of Alternaria Toxins via the Extrusion Processing of Whole-Grain Red Sorghum Flour

This study delved into the impact of two extrusion processing parameters-screw speed (SS at 400, 600, 800 RPM) and material moisture content in the extruder barrel (M at 12, 15, 18%) at constant feed rate (50 kg/h)-on reducing the content of alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), and tentoxin (TEN) in whole-grain red sorghum flour. Ultra-performance liquid chromatography combined with a triple-quadrupole mass spectrometer (UPLC-MS/MS) was employed for the determination of Alternaria toxin levels. The extruder die temperature fluctuated between 136 and 177 °C, with die pressures ranging from 0.16 to 6.23 MPa. The specific mechanical energy spanned from 83.5 to 152.3 kWh/t, the torque varied between 88 and 162.8 Nm, and the average material retention time in the barrel ranged from 5.6 to 13 s. The optimal parameters for reducing the concentration of all Alternaria toxins with a satisfactory quality of the sorghum snacks were: SS = 400 RPM, M = 12%, with a reduction of 61.4, 76.4, 12.1, and 50.8% for AOH, AME, TeA, and TEN, respectively.

Occurrence and Determination of Alternaria Mycotoxins Alternariol, Alternariol Monomethyl Ether, and Tentoxin in Wheat Grains by QuEChERS Method

The Alternaria mycotoxins such as alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN) are mycotoxins, which can contaminate cereal-based raw materials. Today, wheat is one of the most important crops in temperate zones, and it is in increasing demand in the Western Balkans countries that are urbanizing and industrializing. This research aimed to investigate the occurrence and determine the concentration of Alternaria mycotoxins AOH, AME, and TEN in wheat samples from the Republic of Serbia and the Republic of Albania, harvested in the year 2020 in the period between 15 June and 15 July. A total of 80 wheat grain samples, 40 from each country, were analyzed by an QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. From the obtained results, it can be seen that the mean concentration of AOH was 3.3 µg/kg and AME was 2.2 µg/kg in wheat samples from Serbia, while TEN from both Serbia and Albania was under the limit of quantification (<LOQ). The maximum of AOH and AME mycotoxins was recorded only in wheat grain samples collected in the Republic of Serbia (5.3 and 2.3 µg/kg). In conclusion, Alternaria mycotoxins have concentrations above the LOQ, which could be potentially considered a health hazard to both humans and animals.

Distinction of Alternaria Sect. Pseudoalternaria Strains among Other Alternaria Fungi from Cereals

Species of the genus Alternaria are ubiquitous and frequently isolated from various plants, including crops. There are two phylogenetically and morphologically close Alternaria sections: the relatively well-known Infectoriae and the rarely mentioned Pseudoalternaria. Currently, the latter includes at least seven species that are less studied and sometimes misidentified. To perform precise identification, two primers (APsF and APsR) were designed and a sect. Pseudoalternaria-specific PCR method was developed. Thirty-five Russian A. infectoria-like strains were then examined. Five strains were found to be the members of the sect. Pseudoalternaria. Additionally, specificity of the previously developed primer set (Ain3F and Ain4R) was checked. It was found to be highly specific for sect. Infectoriae and did not amplify sect. Pseudoalternaria DNA. Identification of strains of the sect. Pseudoalternaria was supported and refined by phylogenetic reconstruction based on analysis of two loci, the glyceraldehyde-3-phosphate dehydrogenase gene (gpd), and the plasma membrane ATPase gene (ATP). These fungi belonged to Alternaria kordkuyana and A. rosae, which were the first detection of those taxa for the Eastern Europe. Alternaria kordkuyana was isolated from cereal seeds and eleuthero leaves. Alternaria rosae was obtained from oat seed. All strains of sect. Pseudoalternaria were not able to produce alternariol mycotoxin, as well as the majority of A. sect. Infectoriae strains.

Providing Biological Plausibility for Exposure–Health Relationships for the Mycotoxins Deoxynivalenol (DON) and Fumonisin B1 (FB1) in Humans Using the AOP Framework

Humans are chronically exposed to the mycotoxins deoxynivalenol (DON) and fumonisin B1 (FB1), as indicated by their widespread presence in foods and occasional exposure in the workplace. This exposure is confirmed by human biomonitoring (HBM) studies on (metabolites of) these mycotoxins in human matrices. We evaluated the exposure–health relationship of the mycotoxins in humans by reviewing the available literature. Since human studies did not allow the identification of unequivocal chronic health effects upon exposure to DON and FB1, the adverse outcome pathway (AOP) framework was used to structure additional mechanistic evidence from in vitro and animal studies on the identified adverse effects. In addition to a preliminary AOP for DON resulting in the adverse outcome (AO) ‘reduced body weight gain’, we developed a more elaborated AOP for FB1, from the molecular initiating event (MIE) ‘inhibition of ceramide synthases’ leading to the AO ‘neural tube defects’. The mechanistic evidence from AOPs can be used to support the limited evidence from human studies, to focus FB1- and DON-related research in humans to identify related early biomarkers of effect. In order to establish additional human exposure–health relationships in the future, recommendations are given to maximize the information that can be obtained from HBM.

Natural Occurrence of Alternaria Fungi and Associated Mycotoxins in Small-Grain Cereals from The Urals and West Siberia Regions of Russia

Alternaria fungi dominate the grain microbiota in many regions of the world; therefore, the detection of species that are able to produce mycotoxins has received much attention. A total of 178 grain samples of wheat, barley and oat obtained from the Urals and West Siberia regions of Russia in 2017–2019 were included in the study. Grain contamination with Alternaria fungi belonging to sections Alternaria and Infectoriae was analysed using qPCR with specific primers. The occurrence of four mycotoxins produced by Alternaria, AOH, AME, TEN, and TeA, was defined by HPLC-MS/MS. Alternaria DNA was found in all analysed grain samples. The prevalence of DNA of Alternaria sect. Alternaria fungi (range 53 × 10⁻⁴–21,731 × 10⁻⁴ pg/ng) over the DNA of Alternaria sect. Infectoriae (range 11 × 10⁻⁴‒4237 × 10⁻⁴ pg/ng) in the grain samples was revealed. Sixty-two percent of grain samples were contaminated by at least two Alternaria mycotoxins. The combination of TEN and TeA was found most often. Eight percent of grain samples were contaminated by all four mycotoxins, and only 3% of samples were free from the analysed secondary toxic metabolites. The amounts varied in a range of 2–53 µg/kg for AOH, 3–56 µg/kg for AME, 3–131 µg/kg for TEN and 9–15,000 µg/kg for TeA. To our knowledge, a new global maximum level of natural contamination of wheat grain with TeA was detected. A positive correlation between the amount of DNA from Alternaria sect. Alternaria and TeA was observed. The significant effects of cereal species and geographic origin of samples on the amounts of DNA and mycotoxins of Alternaria spp. in grain were revealed. Barley was the most heavily contaminated with fungi belonging to both sections. The content of AOH in oat grain was, on average, higher than that found in wheat and barley. The content of TEN in the grain of barley was lower than that in wheat and similar to that in oat. The content of TeA did not depend on the cereal crop. The effect of weather conditions (summer temperature and rainfall) on the final fungal and mycotoxin contamination of grain was discussed. The frequent co-occurrence of different Alternaria fungi and their mycotoxins in grain indicates the need for further studies investigating this issue.

Occurrence of Alternaria and Other Toxins in Cereal Grains Intended for Animal Feeding Collected in Slovenia: A Three-Year Study

In recent years, the less-studied Alternaria mycotoxins have attracted increasing interest due to the lack of survey data and their ability to cause toxic effects in animals and humans. To fill the gap, the aim of this three-year survey was to investigate the presence and co-occurrence of Alternaria and other mycotoxins in a total of 433 cereal grain samples from Slovenian farms and agricultural cooperatives from 2014 to 2016. Using the multi-mycotoxin method, 14 mycotoxins were determined. In 53% of 433 analysed samples, contamination with at least one mycotoxin was found. Deoxynivalenol (DON) and tenuazonic acid (TeA) were present in 32% and 26% of cereal grain samples, respectively, whereas alternariol (AOH), tentoxin (TEN), alternariol monomethyl ether (AME), 3- and 15-acetyldeoxynivalenol (3- and 15-AcDON), and zearalenone (ZEN) were present in fewer than 15% of the samples. Ochratoxin A (OTA) was found in one rye sample, while diacetoxyscirpenol (DAS), HT-2 and T-2 toxin, and fumonisins B1 and B2 (FB1 and FB2) were not detected. The highest maximum and median concentrations of Alternaria toxins were determined in spelt in 2016 (TeA, 2277 µg/kg and 203 µg/kg, respectively), and those of Fusarium toxins in wheat in 2015 (DON, 4082 µg/kg and 387 µg/kg, respectively). The co-occurrence of two or more mycotoxins was found in 43% of the positive samples. The correlations between Alternaria toxins were very weak but statistically significant (r: 0.15-0.17, p: 0.0042-0.0165). A well-known correlation between Fusarium toxins DON and ZEN was weak and highly significant (r = 0.28, p < 0.0001).

Incidence of Fusarium Mycotoxins in Wheat and Maize from Albania

In this study, ten Fusarium toxins were analysed in wheat and maize commodities from Albania. In total, 71 samples of wheat and 45 samples of maize were collected from different producing regions. The analytical procedure consisted of a simple one-step sample extraction followed by the determination of toxins using liquid chromatography coupled with tandem mass spectrometry. Fusarium toxins were found in 23% of the analysed wheat samples and in 78% of maize samples. In maize samples, most often fumonisins B1 (FB1) and B2 (FB2) were found. They were present in 76% of samples. They were detected in all positive samples except in one with concentrations ranging from 59.9 to 16,970 μg/kg. The sum of FB1 and FB2 exceeded the EU maximum permitted level (4000 μg/kg) in 31% of maize samples. In wheat samples, the only detected Fusarium mycotoxin was deoxynivalenol (DON), present in 23% of samples. In one sample with the concentration of 1916 μg/kg, the EU maximum permitted level (1250 μg/kg) was exceeded. This is the first report on the presence of Fusarium toxins in wheat and maize grains cultivated in Albania.

Molecular Identification and Mycotoxin Production by Alternaria Species Occurring on Durum Wheat, Showing Black Point Symptoms

Black point is a fungal disease of wheat, mainly associated with mycotoxigenic Alternaria species. Affected wheat kernels are characterized by dark brown discolouration of the embryo region and reduction of grain quality. Potential risk is the possible accumulation of Alternaria mycotoxins, alternariol (AOH), alternariol-monomethyl ether (AME), tenuazonic acid (TA), and altenuene (ALT), provided by haemato-toxic, genotoxic, and mutagenic activities. One hundred and twenty durum wheat samples belonging to 30 different genotypes grown in Bologna and Modena areas, in Italy, showing black point symptoms, were analyzed for Alternaria species and their mycotoxin contamination. Alternariol was selected as an indicator of the capability of the Alternaria species to produce mycotoxin in vivo in field conditions. The data showed that Alternaria species occurred in 118 out of 120 wheat kernels samples, with the incidence of infected kernels ranging between 1% and 26%. Moreover, AOH was detected by using a HPLC with a diode array detector (LC-DAD) in 98 out of 120 samples with values ranging between 24 and 262 µg Kg⁻¹. Ninety-two Alternaria representative strains, previously identified morphologically, were identified at species/section level using gene sequencing, and therefore were analyzed for their mycotoxin profiles. Eighty-four strains, phylogenetically grouped in the Alternaria section, produced AOH, AME, and TA with values up to 8064, 14,341, and 3683 µg g⁻¹, respectively, analyzed by using a LC-DAD. On the other hand, eight Alternaria strains, included in Infectoriae Section, showed a very low or no capability to produce mycotoxins.

Alternariol disturbs oocyte maturation and preimplantation development

Alternariol (AOH) is produced by fungi of the genus Alternaria and can be found in fruits, vegetables, and grains. Besides the oestrogenic activity demonstrated in vitro, this mycotoxin causes DNA damage and cell cycle arrest. Based on this, the effect of AOH was investigated on porcine female gametes during in vitro maturation and subsequent initial embryo development. A first experiment assessed a dose-response effect of AOH (5, 10, or 20 μmol/l) on cumulus expansion and in vitro oocyte nuclear maturation, in the presence or absence of follicular fluid (FF). A second experiment evaluated the effect of AOH (5, 10, or 20 μmol/l) exposure during porcine oocyte maturation, initial embryo development, or both periods, on preimplantation embryo development. Although FF protected oocytes from the deleterious effect of AOH, it did not avoid a decrease in cumulus cells expansion (5 μmol/l AOH regardless of the presence of FF). Moreover, exposure to AOH resulted in the degeneration of oocytes (10 μmol/l AOH in the absence of FF) and the occurrence of nuclear aberrations in mature oocytes (10 μmol/l AOH in the absence of FF and 20 μmol/l AOH in the presence of FF). Exposure to 5 μmol/l AOH during oocyte in vitro maturation was sufficient to impair initial embryo development.

Effect of Wheat Milling Process on the Distribution of Alternaria Toxins

Alternaria toxins are mycotoxins produced by various Alternaria species which, besides the Fusarium species, represent the principal contaminants of wheat worldwide. As currently, only limited information on the behaviour of Alternaria toxins during processing of cereals is available, the objective of this study was to investigate the effect of the dry milling process of wheat on Alternaria toxins distribution. Alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TeA) content were analysed by high performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in all milling fractions of untreated (control), fungicide-treated, Alternaria tenuissima inoculated and commercial wheat sample. After dry milling process, in last break and milling flows and by-products, increased concentration of examined Alternaria toxins was detected. TeA was quantified in almost all milling fractions in all tested wheat samples, while AOH and AME were detectable mostly in last break and milling flows and by-products. In respect to the contamination with Alternaria toxins, white flour can be considered as relatively safe product. Since Alternaria toxins are concentrated mainly in the peripheral parts of the kernel, a special attention should be given to their content in low-grade flours and milling by-products.