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Scope Alternaria fungi are widely distributed plant pathogens infecting grains and vegetables and causing major harvest losses in the field and during postharvest storage. Besides, consumers are endangered by the formation of toxic secondary metabolites. Some of these secondary metabolites are chemically characterized as mycotoxins, but the majority of the Alternaria mycobolome still remains unknown. Methods and results Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) and LC-MS/MS are combined for the non-targeted and targeted analysis of the metabolome of three A. alternata isolates and one A. solani isolate. Due to the ultra-high resolution of FTICR-MS, unique molecular formulae are assigned to measured m/z signals. The molecular formulae are matched to entries of the databases Antibase and Kyoto Encyclopedia of Genes and Genomes. The non-targeted analysis of the fungal extracts reveals variations in the secondary metabolite profile of A. alternata and A. solani. Differences in the biosynthesis of dibenzo-α-pyrones, perylene quinones, tentoxin, and tenuazonic acid of the A. alternata and A. solani isolates are determined applying targeted LC-MS/MS. Conclusion FTICR-MS analyses reveal clear differences in the metabolic profile of the A. solani and the A. alternata isolates.

A stable isotope dilution LC-MS/MS multi-mycotoxin method was developed for 12 different Fusarium toxins including modified mycotoxins in beer (deoxynivalenol-3-glucoside, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyl-deoxynivalenol, HT2-toxin, T2-toxin, enniatin B, B1, A1, A, beauvericin and zearalenone). As sample preparation and purification of beer a combined solid phase extraction for trichothecenes, enniatins, beauvericin and zearalenone was firstly developed. The validation of the new method gave satisfying results: intra-day and inter-day precision and recoveries were 1-5%, 2-8% and 72-117%, respectively. In total, 61 different organic and conventional beer samples from Germany and all over the world were analyzed by using the newly developed multi-mycotoxin method. In summary, deoxynivalenol, deoxynivalenol-3-glucoside, 3-acetyldeoxynivaleneol and enniatin B were quantified in rather low contents in the investigated beer samples. None of the other monitored Fusarium toxins like 15-acetyldeoxynivalenol, HT2- and T2-toxin, zearalenone, enniatin B1, A1, A or beauvericin were detectable.

With its ultrahigh resolution power and excellent mass accuracy, Fourier transform ion cyclotron resonance mass spectrometry is the perfct tool to analyze the “foodome” as the set of all polar small molecular compounds present in an investigated food sample. We present here selected applications of this technique in unraveling the metabolome in complex foods (thermally affected, fermentation products, distillates) such exemplified with Maillard reaction products or with wines and spirits. Technical considerations for high resolution mass analyzers are provided from a practical point of view. Moreover, aspects of food safety and nutritional quality are covered by presenting applications to the mycobolome of Alternaria fungi and vitamins of the folate group, respectively.

Alternaria fungi are widely distributed saprophytes and plant pathogens. As pathogens, Alternaria fungi infect crops and vegetables and cause losses in the fields and during postharvest storage. While farmers suffer from declining yields, consumers are endangered by the formation of secondary metabolites, because some of these exhibit a pronounced toxicological potential. The evaluation of the toxicological capabilities is still ongoing and will contribute to a valid risk assessment. Additionally, data on the incidence and the quantity of Alternaria mycotoxins found in food products is necessary for dietary exposure evaluations. A sensitive LC-MS/MS method for the determination of the Alternaria mycotoxins alternariol (AOH), alternariol monomethylether (AME), tentoxin (TEN), altertoxin I (ATX I), alterperylenol (ALTP), and tenuazonic acid (TA) was developed. AOH, AME, and TA were quantified using stable-isotopically labeled standards. TEN, ATX I, and ALTP were determined using matrix matched calibration. The developed method was validated by using starch and fresh tomato matrix and resulted in limits of detection ranging from 0.05 to 1.25 μg/kg for starch (as a model for cereals) and from 0.01 to 1.36 μg/kg for fresh tomatoes. Limits of quantification were determined between 0.16 and 4.13 μg/kg for starch and between 0.02 and 5.56 μg/kg for tomatoes. Recoveries varied between 83 and 108% for starch and between 95 and 111% for tomatoes. Intra-day precisions were below 4% and inter-day precisions varied from 3 to 8% in both matrices. Various cereal based infant foods, jars containing vegetables and fruits as well as tomato products for infants were analyzed for Alternaria mycotoxin contamination (n = 25). TA was the most frequently determined mycotoxin and was detected in much higher contents than the other toxins. AME and TEN were quantified in many samples, but in low concentrations, whereas AOH, ATX I, and ALTP were determined rarely, among which AOH had higher concentration. Some infant food products were highly contaminated with Alternaria mycotoxins and the consumption of these individual products might pose a risk to the health of infants. However, when the mean or median is considered, no toxicological risk was obvious.