Across climates and limits: a Brazil-Mediterranean benchmark of aflatoxins in peanuts and peanut butters

Aflatoxins in peanuts and peanut products remain a key food-safety concern, with occurrence shaped by climate and post-harvest conditions. This study aimed to compare fungal contamination and aflatoxin occurrence in peanuts and peanut butters acquired in Brazil and in Mediterranean markets. Thirty-two samples (21 peanuts; 11 peanut butters) were analyzed for water activity (a_w), moisture, aflatoxins (HPLC), microbiological counts, Salmonella and Listeria monocytogenes detection, culture-dependent fungal identification, and fungal metataxonomics. Total aflatoxins in Brazilian peanuts ranged from 2.10 to 9.28 μg/kg, none exceeding Brazil's 20 μg/kg limit. In Mediterranean peanuts, one sample exceeded the European Union (EU) 4.0 μg/kg total-aflatoxin limit. In Mediterranean peanut butters, two samples exceeded the EU limit. No Brazilian peanut butter exceeded the national limit. Isolates from Mediterranean peanuts were identified as Cladosporium (50%), followed by Aspergillus (25%), Penicillium (12.5%), Talaromyces (6.25%), and Trechispora (6.25%), whereas Brazilian isolates were exclusively Aspergillus spp.. Metataxonomics of the most contaminated Brazilian peanuts revealed communities dominated by Aspergillus and Fusarium, with occasional co-occurrence of eight other fungal genera. Despite generally compliant aflatoxin levels, exceedances against EU limits were observed in some Mediterranean products. Fungal community structure, particularly dominance of Aspergillus section Flavi, appears more indicative of aflatoxin risk than total fungal load, underscoring the value of integrated monitoring (aw/moisture), targeted mycological surveillance, and molecular profiling across production chains.