Characterisation of toxigenic Aspergillus species and assessment of mycotoxin contamination in postharvest dried cocoa beans in Malaysia

Abstract Cocoa ( Theobroma cacao ) is highly susceptible to fungal and mycotoxin contamination during postharvest handling. This study examined Aspergillus species and mycotoxin levels in dried cocoa beans from 12 farms across six Malaysian states: Pokok Jenerih and Sungai Bakap (Penang); Bagan Datuk and Chemor (Perak); Tanjung Karang and Parit Tujuh (Selangor); Tanjung Ipoh and Rembau (Negeri Sembilan); Batu Pahat and Tangkak (Johor); and Durian Tunggal and Jasin (Melaka). Forty-three Aspergillus isolates were identified using morphological traits, DNA sequencing of the internal transcribed spacer (ITS) and β -tubulin ( tub2 ) gene region, and phylogenetic analysis. The species included Aspergillus flavus (10 isolates), Aspergillus niger (9 isolates), Aspergillus tamarii (9 isolates), Aspergillus tubingensis (8 isolates), and Aspergillus aculeatus (7 isolates). Mycotoxigenic potential, assessed via coconut cream agar (CCA), showed all isolates fluoresced, with A. niger exhibiting moderate intensity. Among the 12 samples analysed, one sample from Pokok Jenerih, Penang (representing 8.3% of total samples), exceeded both the fungal load limit (2.9 × 10 5 cfu/g) and moisture threshold (8.91%). High-performance liquid chromatography (HPLC) analysis revealed aflatoxins (AFs) in 33% and ochratoxin A (OTA) in 58% of samples. Aflatoxins (AFB 1 , AFB 2 , AFG 1 , and AFG 2 ) in the Pokok Jenerih sample surpassed European Union (EU) safety limits, while OTA levels remained within regulatory thresholds. Co-occurrence of AFs and OTA was observed in samples from Pokok Jenerih and Jasin. The study reveals various Aspergillus species and AFs and OTA contaminations in Malaysian cocoa beans, particularly in certain regions, underscoring the urgent need for improved postharvest handling practices to ensure food safety and compliance with international standards.