Quantification of multi-mycotoxin in cereals (maize, maize porridge, sorghum and wheat) from Limpopo province of South Africa

Mycotoxins are secondary metabolites that are produced by filamentous mycotoxigenic fungi belonging to theAlternaria, Aspergillus, FusariumandPenicilliumgenera amongst others. Multi-class mycotoxins were extracted from 55 cereal samples and analysed using liquid chromatography-tandem mass spectrometry. The adopted extraction method for maize, maize porridge, sorghum and wheat was comprehensively validated. This method was further tested to determine the natural occurrence of mycotoxins in foodstuffs. Twelve (12) out of 22 mycotoxins were detected in maize, maize porridge, sorghum and wheat, including alpha-zearalenol (alpha-ZEL) (89%), fumonisin B-3(FB3) (84%), fumonisin B-1(FB1) (80%), tenuazonic acid (TeA) (78%), ochratoxin B (42%), deoxynivalenol (DON) (12%), ochratoxin A (11%), 3-acetyldeoxynivalenol (7%), sterigmatocystin (STG) (6%), 15-acetyldeoxynivalenol (2%), cyclopiazonic acid (CPA) (2%) and aflatoxin B-2(2%). The data revealed high incidence rate of alpha-ZEL (range: 6.5-70.5 mu g kg(-1)) in all matrices. Maize samples had high mycotoxin co-occurrence compared to other matrices. All recovered mycotoxins in food commodities were within the maximum regulatory limits, with the exception of fumonisins (FB(1)and FB3) exceeded the South African and European Commission regulation, and the highest concentration was 2153 mu g kg(-1)in maize. It is essential to monitor the level of emerging mycotoxins in food commodities from rural areas as trace amount of CPA (< limit of quantification), STG (range: 0.30-0.74 mu g kg(-1)) were detected and high concentration of TeA (292.7 mu g kg(-1)) was detected in sorghum. The occurrence of these mycotoxins further encourages frequent analyses, their co-occurrence in the samples poses a significant threat to public health and more emphasis should thus be placed on reducing the contamination levels of these toxins in staples.