Temperature and water activity influence on simultaneous production of AAL toxins by Alternaria arborescens on tomato medium

Abstract

Alternaria spp. have been reported to be the most frequent phytopathogenic fungi invading tomatoes. Certain species are capable of producing several mycotoxins in infected plants and in agricultural commodities. AAL toxins are produced by Alternaria arborescens, which is the causal agent of tomato stem canker, and one of the species involved in the tomato black mold. AAL toxins include five congeners, TA, TB, TC, TD and TE, structurally similar. The objective of this study was to determine the effect of water activity (aw, 0.995, and 0.950) and temperature (6, 15, 20, 25 and 30 °C) on simultaneous AAL toxins production by Alternaria arborescens. The maximum accumulation of AAL toxins occurred at 0.995 aw after 40 days of incubation at 30 °C. None of the toxins was detected at temperatures below 30 °C at any aw during the whole incubation period. The results obtained here could be extrapolated to evaluate the risk of toxin accumulation in tomato fruit and tomato products.