Effects of Preharvest Application of Oxalic Acid, γ-Aminobutyric Acid, and Melatonin on the Microbiological and Physicochemical Quality of Dried Figs at Commercial Harvest and During Storage

The objective of this study was to evaluate the preharvest application of γ-aminobutyric acid (GABA), melatonin (MT), and oxalic acid (OA), at different concentrations and application frequencies, on the physicochemical and microbiological quality of dried figs (cv. Calabacita) at commercial harvest and after 3 and 6 months of refrigerated storage. A further aim was to determine their impact on fungal populations and mycotoxin production. The results showed that untreated dried figs had a higher frequency of Aspergillus welwitschiae, A. tubingensis, and Aspergillus section Flavi, whereas elicitor-treated figs exhibited a lower incidence of toxigenic fungi. A. welwitschiae was the main ochratoxin A (OTA)-associated species detected, although the proportion of OTA-positive figs was lower in elicitor-treated samples than in the control. Aflatoxins (AFs) were detected only sporadically in 2 mM OA treatments, consistent with the limited activity of A. flavus at low storage temperatures. Conversely, Penicillium spp. were widespread but were associated with citrinin (CIT) production only under 2 mM OA treatments. Among the Alternaria toxins, alternariol (AOH) was detected solely in dried figs treated with 1 mM OA. Notably, all investigated mycotoxins were below the limit of detection (