Routine LC-MS/MS method for quantifying <i>Alternaria</i> toxins in tomatoes at harvest stage and during processing

A high-performance liquid chromatography tandem mass spectrometry method has been developed and validated to quantify alternariol, alternariol monomethyl ether, tenuazonic acid, altenuene, altertoxin I, and tentoxin, and implemented to better understand the risks associated with <i>Alternaria</i> contamination of tomatoes and fate of the toxins during processing. This method has been developed for routine use, by reducing the cost, duration, and complexity of manipulations. Limits of quantification were below EU recommendations 2022/553, reaching 1.2-3.7 µg kg^-1 for alternariol and alternariol monomethyl ether and 9.4-18.4 µg kg^-1 for tenuazonic acid depending on the matrix. Apparent recovery ranged between 85 and 103%, and intraday repeatability was <15%. Different <i>Alternaria</i> strains isolated from tomatoes were assessed for their toxin production profiles, and the impact of processing operations on <i>Alternaria</i> toxins naturally occurring in tomatoes was evaluated on a pilot scale. Tenuazonic acid was the predominant toxin produced by <i>Alternaria</i> strains and contaminating tomatoes. Processing operations did not reduce toxin accumulation, which demonstrates its thermostability. Additionally, tomato skin and seeds residues, which are reused for different applications, was 2.6 times more contaminated than tomato pulp.