toxins Article Occurrence of Regulated Mycotoxins and Other Microbial Metabolites in Dried Cassava Products from Nigeria Adebayo B. Abass 1 , Wasiu Awoyale 1,2, *, Michael Sulyok 3 and Emmanuel O. Alamu 1 1 International Institute of Tropical Agriculture, PMB 5320 Oyo Road, Ibadan 200285, Oyo State, Nigeria; a.abass@cgiar.org (A.B.A.); o.alamu@cgiar.org (E.O.A.) 2 Department of Food Science and Technology, Kwara State University Malete, PMB 1530, Ilorin 240001, Kwara State, Nigeria 3 Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenzstr. 20, A-3430 Tulln, Austria; michael.sulyok@boku.ac.at * Correspondence: wawoyale0101@gmail.com or w.awoyale@cgiar.org; Tel.: +23-480-6214-6482 Received: 4 June 2017; Accepted: 26 June 2017; Published: 29 June 2017 Abstract: Dried cassava products are perceived as one of the potential sources of mycotoxin ingestion in human foods. Processing either contributes to the reduction of toxins or further exposes products to contamination by microorganisms that release metabolic toxins into the products. Thus, the prevalence of microbial metabolites in 373 processed cassava products was investigated in Nigeria. With the use of liquid chromatography tandem-mass spectrometry (LC-MS/MS) for the constituent analysis, a few major mycotoxins (aflatoxin B 1 and G 1 , fumonisin B 1 and B 2 , and zearalenone) regulated in food crops by the Commission of the European Union were found at concentrations which are toxicologically acceptable in many other crops. Some bioactive compounds were detected at low concentrations in the cassava products. Therefore, the exposure of cassava consumers in Nigeria to regulated mycotoxins was estimated to be minimal. The results provide useful information regarding the probable safety of cassava products in Nigeria. Keywords: cassava products; Nigeria; emerging mycotoxins; regulated mycotoxins; microbial metabolite; LC/MS; human exposure; food safety; food standards 1. Introduction The cassava root (Manihot esculenta Crantz) significantly contributes to food security, incomes, and employment opportunities in the rural areas of Sub-Saharan Africa [1], especially in Nigeria, the world’s largest cassava producer [2]. Significant post-harvest deterioration of fresh cassava roots occurs because of the natural high moisture content, which accelerates microbial deterioration and undesirable biochemical changes in the products [3]. Processing is used to extend the shelf life, facilitate transport and, most importantly, detoxify the roots by removing the inherent cyanogens [4–6]. Hence, cassava root is processed in Nigeria into gari, tapioca, lafun, fufu, starch, and high-quality cassava flour (HQCF), among others, with all the products having different physical properties due to variations in processing methods [7–9]. However, these processing methods, as well as the environments and natural microflora, influence the types and concentrations of microbial metabolites in the final food products [10,11]. The various processing methods for cassava in Nigeria often result in a range of food and feed products. Cassava starch and high-quality cassava flour (HQCF) are dried, unfermented products that must be dried immediately to avoid fermentation [12,13]. Starch is produced by peeling the roots, washing, grating, pulverizing, wet-sieving, sedimentation, decanting, dewatering, drying, and milling. Toxins 2017, 9, 207; doi:10.3390/toxins9070207 www.mdpi.com/journal/toxins