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Cape Peninsula University of Technology (2021)

Mycotoxins in sorghum bicolor and pennisetum glaucum collected from the Oshana Region of Northern Namibia

Kaela, Calvin Rhabelani Bither

Titre : Mycotoxins in sorghum bicolor and pennisetum glaucum collected from the Oshana Region of Northern Namibia

Auteur : Kaela, Calvin Rhabelani Bither

Université de soutenance : Cape Peninsula University of Technology

Grade : Master in Agriculture 2021

Résumé partiel
This project formed part of a research collaboration between the Cape Peninsula University of Technology and the University of Namibia (Windhoek, Namibia). The study involved mycological and multiple mycotoxin surveillance of smallholder farms, and processed sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) products sold at open markets in the Oshana region of northern Namibia. Despite strict regulations worldwide, mycotoxin levels in grains are not regulated in Namibia. Smallholder farming communities in northern Namibia are heavily reliant on sorghum and pearl millet as staple food. The Oshakati smallholder farmers service both the Oshakati and Ondangwa open markets. Sorghum and pearl millet samples were collected from smallholder farmers’ households in Oshakati and from randomly selected vending stalls from the Oshakati and Ondangwa open markets. The occurrence of mycotoxigenic fungi on sorghum and pearl millet was determined using conventional mycological methods as well as validated molecular techniques utilizing species-specific primers and quantitative Real-time PCR (qPCR). The concentrations of multiple mycotoxins [aflatoxin B1 (AFB1), fumonisin B1 (FB1), fumonisin B2 (FB2), fumonisin B3 (FB3), ochratoxin A, deoxynivalenol, zearalenone (ZEA), nivalenol and moniliformin] were determined with a validated liquid chromatography with tandem mass spectrometry analytical method. Morphological analyses indicated higher fungal contamination levels in the raw (whole grain) and processed sorghum as compared to pearl millet (P<0.05). No Aspergillus spp. were detected in the raw sorghum samples. The contamination frequencies of Fusarium spp. in raw sorghum and pearl millet were both 80%. Fusarium and Aspergillus spp. co-occurred in 30% of raw pearl millet samples. In processed samples, contamination with Fusarium and Aspergillus spp. was detected in 74% and 100% samples, respectively.

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Page publiée le 18 mai 2022