Occurrence of <i>Alternaria</i> secondary metabolites in milling oats and its de-hulled fractions from harvest years 2017 to 2021

In this study, secondary metabolites produced by <i>Alternaria</i> were investigated for their presence in milling oats. For this purpose, pre-cleaned milling oat samples (<i>n</i> = 193), intended for human consumption, out of harvest years 2017 to 2021 originating from different northern European countries were analysed by LC-MS/MS. Alternariol and alternariol methyl ether were positively identified in 38% of the samples with mean values of 2.1 µg/kg and 1.2 µg/kg, respectively. The highest concentrations of 50.5 µg/kg alternariol and 24.2 µg/kg of alternariol methyl ether were detected in a Latvian sample. Tenuazonic acid was found in 45% of all samples, with a mean concentration of 28.9 µg/kg and a maximum concentration of 1430 µg/kg, also in a Latvian sample. Tentoxin was detected in 49% of all samples with a mean value of 1.7 µg/kg. The <i>Alternaria</i> metabolite most frequently detected in 96% of all samples was infectopyrone with a mean concentration of 593 µg/kg and a maximum value reaching up to 3990 µg/kg in a German sample. In addition, eight oat samples were selected to investigate to what extent the <i>Alternaria</i> metabolites are distributed between the oat hulls and the oat kernels. After de-hulling, approximately 23% of <i>Alternaria</i> metabolites were found in the remaining oat kernels. According to the results, alternariol, infectopyrone and altersetin were present in the kernels with the lowest proportion of 10%–20% on average, respectively. The values for tentoxin showed that about 60% of tentoxin was contained in the hulls, while almost 40% remained in the oat kernel. This suggests that potential health risks posed by <i>Alternaria</i> secondary metabolites and metabolites of other fungal genera in milling oats can be reduced by de-hulling.本研究针对制粉用燕麦中链格孢属（*Alternaria*）产生的次生代谢产物的存在情况展开调查。本研究选取2017至2021年收获期、源自北欧不同国家的193份供人类食用的预清洗制粉燕麦样品（*n* = 193），采用液相色谱-串联质谱（LC-MS/MS）进行分析。 在38%的样品中成功确证检出交链孢酚（alternariol）与交链孢酚单甲醚（alternariol methyl ether），二者平均含量分别为2.1 µg/kg和1.2 µg/kg。其中一份拉脱维亚样品中检出的浓度最高：交链孢酚达50.5 µg/kg，交链孢酚单甲醚达24.2 µg/kg。 细交链孢菌酮酸（tenuazonic acid）在45%的样品中被检出，平均浓度为28.9 µg/kg，最高浓度达1430 µg/kg，该高值样本同样来自拉脱维亚。 细格菌素（tentoxin）在49%的样品中被检出，平均含量为1.7 µg/kg。 在所有样品中检出率最高的链格孢属代谢产物为侵染吡喃酮（infectopyrone），检出率达96%，平均浓度为593 µg/kg，其中一份德国样品中其最高浓度可达3990 µg/kg。 此外，本研究选取8份燕麦样品，以探究链格孢属次生代谢产物在燕麦壳与燕麦籽粒中的分布特征。经脱壳处理后，约23%的链格孢属次生代谢产物留存于燕麦籽粒中。 结果显示，交链孢酚、侵染吡喃酮与交链孢素（altersetin）在籽粒中的占比最低，平均仅为10%~20%。细格菌素的分布数据表明，约60%的细格菌素留存于燕麦壳中，剩余近40%则存在于燕麦籽粒内。 综上，脱壳处理可降低制粉用燕麦中链格孢属次生代谢产物及其他真菌属代谢产物所带来的潜在健康风险。