Assessment of mycotoxin contamination in traditional leafy vegetables sold in the Free State, South Africa.

Abstract

Traditional leafy vegetables (TLVs) are an essential supplement to grain-based diets. They are a valuable source of nutrition in rural areas where exotic species are unavailable and contribute substantially to protein, mineral and vitamin intake. However, they are seasonal and highly perishable, making them susceptible to contamination. This study conducted a market survey for TLVs in the Free State Province, South Africa, to determine the most consumed TLVs, preservation methods, packaging and storage conditions. Fungal contaminants and associated mycotoxins were identified. A descriptive cross-sectional survey design was used to collect data from formal and informal markets in the Free State's rural and urban areas. Interviews were conducted with 60 vendors that sold TLVs used either as food or medicines using semi-structured questionnaires. Data collected from the interviews were analysed using descriptive statistics. The interviews mentioned ten traditional leafy vegetables, but six species, Urtica dioica L., Rorripa nudiuscula Thell., Lepidium capense Thunb., Amaranthus hybridus L., Chenopodium album L. and Cucurbita maxima, were readily available and collected for mycological contamination tests. Nine fungal species; Epicoccum sorghinum, Alternaria alternate, Phoma sp., Cladosporium sp., Rhizopus oryzae, Nothophoma quercina, Fusarium sp., Didymella glomerata and Didymella macrostoma, were present on the vegetable samples evaluated. To further assess the safety of TLVs, mycotoxin analysis and quantification were carried out using a rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS). The samples were tested for Aflatoxin B1, Deoxynivalenol, Nivalenol, Ochratoxin A, Zearalenol, Fumonisin B1, Fumonisin B2, and Fumonisin B3. Of the tested vegetable samples, only Amaranthus hybridus L. and Chenopodium album L. had traces of the mycotoxins; Fumonisin B1 and Fumonisin B2. The results obtained in this study showed that TLVs are safe for consumption. Nevertheless, as much as the mycotoxins detected were below set limits, cumulative exposure may pose a health risk to consumers. Consequently, TLVs traders and consumers must be made aware of the risks associated with mycotoxins and educated on the importance of proper hygiene, preservation and storage practices.