Alternaria mycotoxins in tomato products: an emerging or long-standing problem?

Abstract

Although Alternaria toxins are considered emerging, their occurrence has been reported in different food, commodities and raw materials, for several years. Fruits and vegetables, as well as their derivatives are frequently contaminated with these toxins and tomato products have been identified among the most relevant contributors to human exposure to these mycotoxins. A study performed in Argentina in 2006 already showed a high incidence of Alternaria toxins in tomato products, with 49 % samples contaminated with either alternariol (AOH), alternariol monomethyl ether (AME) or tenuazonic acid (TeA). TeA and AME were the most frequent toxins (29 and 26 %, respectively), while AOH was found in low frequency (6 %) but significantly higher levels (up to 8756 µg/kg). The aim of the present study was to evaluate the evolution of the Argentinean market for tomato products in the last 15 years regarding the natural occurrence of Alternaria toxins.A total of 79 samples of tomato products from the Argentinean market were collected from 2019 to 2021. From these, 73 were of Argentinean origin and 6 Italian. Samples consisted of 38 tomato purees, 15 whole peeled tomatoes, 13 crushed tomatoes, 7 concentrated tomato pastes, 4 tomato sauces and 2 tomato pulps. The simultaneous quantification of altenuene (ALT), AOH, AME, altertoxin-I (ATX-I), tentoxin (TEN) and TeA was performed using a validated multi-mycotoxin LC-MS/MS method. From the 73 Argentinean samples, 29 (40%) were contaminated with at least one toxin, while no contamination was detected in the Italian samples. In terms of frequency, TeA and TEN were the predominant toxins (14%) followed by AOH (13%). AME was only detected in 3 samples (4%), in the same proportion than ALT, and ATX-I occurred in 2 samples (3%). Tomato purees showed the highest frequency of contamination (47%), followed by whole peeled tomatoes (38%), and crushed tomatoes and concentrated tomato paste at equal proportion (33%). None of the Alternaria toxins were detected in pulps or sauces. Tomato puree was the only product in which the six mycotoxins naturally occurred. As well, the highest concentration of TeA corresponded to a tomato puree sample (495.7 μg/kg).Comparisons between both surveys showed significant reduction in the levels of contamination. Regarding the three main mycotoxins, TeA remains being the predominant one, but the frequency of AME at present is significantly lower. Changes in agricultural and processing practices and climate change are currently being explored as potential explanation for these changes.