Variation of Fungal Metabolites in Sorghum Malts Used to Prepare Namibian Traditional Fermented Beverages Omalodu and Otombo

Abstract

Sorghum malts, which are important ingredients in traditional fermented beverages, are commonly infected by mycotoxigenic fungi and mycotoxins may transfer into the beverages, risking consumers’ health. Liquid chromatography–tandem mass spectrometry was used to determine variation of fungal metabolites in 81 sorghum malts processed for brewing of Namibian beverages, otombo (n = 45) and omalodu (n = 36). Co-occurrence of European Union (EU)-regulated mycotoxins, such as patulin, aflatoxins (B1, B2, and G2), and fumonisins (B1, B2, and B3) was detected in both malts with a prevalence range of 2–84%. Aflatoxin B1 was quantified in omalodu (44%) and otombo malts (14%), with 20% of omalodu malts and 40% of otombo malts having levels above the EU allowable limit. Fumonisin B1 was quantified in both omalodu (84%) and otombo (42%) malts. Emerging mycotoxins, aflatoxin precursors, and ergot alkaloids were quantified in both malts. Notably, 102 metabolites were quantified in both malts, with 96% in omalodu malts and 93% in otombo malts. An average of 48 metabolites were quantified in otombo malts while an average of 67 metabolites were quantified in omalodu malts. The study accentuates the need to monitor mycotoxins in sorghum malts intended for brewing and to determine their fate in the beverages.

Estimated Burden of Fungal Infections in Namibia

“…Several fungal isolates have been isolated from various forms of food contaminants in Namibia. Several mycotoxins were found in sorghum malts processed for brewing Namibian traditional beverages, some of which were above the EU allowable limit [99]. In an attempt determine the presence of fungal pathogens in Marama beans, an endemic perennial wild tuberous Fabacea that is valued by the indigenous people of the semi-arid land of the Kalahari for its nutritional and medicinal properties, Uzabakiriho et al (2013) identified two fungal isolates, namely Alternaria tenuissima and Phoma spp., which are both part of the Ascomycota family.…”

Fungal Species and Multi-Mycotoxin Associated with Post-Harvest Sorghum (Sorghum bicolor (L.) Moench) Grain in Eastern Ethiopia

“…Among the other Aspergillus metabolites, 3-Nitropropionic acid had the maximum prevalence (61%), while its maximum concentration (817 μg/kg) was surpassed by viomellein (1412 μg/kg), asperfuran (2630 μg/kg), and kojic acid (4584 μg/kg) subsequently. Penicillium metabolites are also commonly reported as contaminants of sorghum grain [ 17 , 51 ]. Presently, flavoglaucin had 100% prevalence, with maximum concentration of 1870 μg/kg.…”

Aptamer-Based Detection of Fumonisin B1: A Systematic Comparison with Conventional and Other Novel Methods

“…On the other hand, one of the main advantages of mass spectrometry detectors is the possibility of performing multiplex analysis, not only for different mycotoxins [48,49,50,53,54,57,58,59,60,61,64,65,66,67,71,72,73,74,77,79,80,187], but also when combined with varied metabolites. Growth regulators, antibiotics, pesticides [51,70,75], and other fungal metabolites [63,68], were simultaneously identified in analysis capable of assessing up to 74 and 90 compounds [62,78]. Mass spectrometry has also been used for assessing mycotoxin transfer from feed to organs and tissue in poultry [80] The importance of novel analytical methods relies on the low sensitivities achieved within a relatively short detection time.…”