Fungal Diversity, Toxigenic Potential, and Multi-Mycotoxin Occurrence in Fresh and Dried Chili Peppers from Retail Markets in Guangzhou, China

This study provides a combined profile of fungal isolates from fresh and dried chili peppers in markets in Guangzhou. Multilocus sequence analysis revealed a wide variety of species, seven of which were reported for the first time from chili pepper (F. annulatum, F. compactum, F. pernambucanum, F. ramsdenii, and F. tardichlamydosporum, P. citrinum and P. steckii). In this research work, quantitative determination using targeted LC–MS/MS of dried chili peppers showed a significantly higher frequency of contamination and higher toxin concentrations than fresh samples. The predominant mycotoxins in dried peppers were DON and FB1, which were present in all the samples at mean levels of 0.56 µg/g and 0.067 µg/g, respectively. AFB1 and OTA were present in all dried samples but were detected only occasionally in fresh peppers. ZEN and CIT were detected at lower concentrations, but more prevalent among dried products (63.6% and 81.8% of all samples, respectively). The aflatoxin B1 (AFB1) level of 180 µg/kg in dried chili samples was 36 times above the EU maximum limit (5 µg/kg), and the OTA level reached 54 µg/kg, exceeding the EU limit by a factor of 2.7 (20 µg/kg). Statistical analysis also showed that all six mycotoxins were statistically higher in dried pepper than in fresh pepper. In vitro evaluation demonstrated that certain Fusarium isolates synthesized FB1. At the same time, Penicillium species, including P. citrinum and P. steckii, consistently produced citrinin, confirming the strong influence of growth substrate on toxin biosynthesis. The frequent occurrence and elevated levels of regulated mycotoxins highlight significant public health concerns and underscore the need for improved postharvest handling and drying practices. These findings provide critical baseline data linking fungal diversity with toxin production dynamics, developing essential guidance for targeted mitigation strategies.