Fungal metabolite and mycotoxins profile of cashew nut from selected locations in two African countries

ABSTRACT

Infestation of food crops by fungi has led to serious economic losses in the international market. There is a paucity of information on the multi-mycotoxin profile of cashew nuts from different geographical locations in Nigeria and South Africa. This work aims at comparing the fungal metabolite profile of cashew nut from two African countries using HPLC-FLD and LC-MS/MS. The differences in distribution of the fungal metabolites across the two countries were also examined. A total of 75 (39; Nigeria, 36; South Africa) roasted cashew nuts were purchased from 14 different locations in Nigeria and 10 major supermarkets in South Africa. The samples were subjected to HPLC analysis for aflatoxin and zearalenone and LC-MS/MS analysis for multiple metabolite profiling. Total aflatoxins (0.03-0.77 µg/kg and 0.01-0.28 µg/kg) and zearalenone (123.2 and 788.6 µg/kg) were quantified in nut samples from South Africa and Nigeria, respectively. In contrast, LC-MS/MS analysis showed that none of the major fungi metabolites except for one (citrinin) was present in detectable amount in Nigerian cashew nuts (31.3 μg/kg). Other microbial metabolites present in the nuts were; Aspergillus metabolites (< LOD to 398 × 10⁴ μg/kg and < LOD to 1760 μg/kg); flavoglaucin (5.4-177.4 μg/kg and 45.5-18,368 μg/kg), 7-hydroxykaurenolide (5.5-45.8 μg/kg and 3.5-33.7 μg/kg), chloramphenicol (0.3-4.5 μg/kg) for South African and Nigerian cashew nuts, respectively. The incidence rate of the fusarium toxins beauvericin and bikaverin were higher in Nigerian cashew nut (100% and 17%) than the South African nuts (8% and 8%), 7-Hydroxykaurenolide and chloramphenicol were found in all the cashew nut samples. A total of 15 unspecific metabolites (17-100%) were recorded in the nuts from both countries. Information on the metabolite profile of cashew nuts will provide useful information for policy makers, border agencies and other health-related Institutes.

Graphical abstract

Fungi metabolites profile of Cashew nut from selected locations in Two African Countries.

*Roasted cashew nut image-www.gettyimages.com

KEYWORDS:

• Cashew nuts
• HPLC-FLD
• LC-MS/MS
• fungal metabolites
• Nigeria
• South Africa

Acknowledgments

The authors are grateful to National Research Foundation (NRF), South Africa and Food Safety Niche Area, North West University, Mafikeng Campus for financing this project.

Conflict of interest

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by the National Research Foundation South Africa [Grant No.: 105882].