Determination of Levels of Ochratoxin a in Wheat, Finger Millet and Sorghum Grains and their Products Retailed in Nairobi County, Kenya
Kibebe, Karoki Peter
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Cereals are major food commodity used in Kenya and their quality determines their suitability to human and animal health. The presence of mycotoxins in cereals and their products is a serious emerging threat to quality of cereals based foodstuff. The main classes of mycotoxins found in cereals are aflatoxins, ochratoxins, fumonisins, deoxynivarenol and trichothecenes. Though aflatoxins are the most toxic mycotoxins, ochratoxin A (OTA) is a possible carcinogen of class 2B. In this study, OTA levels were determined in seventy one (71) different samples comprising of finger millet (Eleusine coracana), sorghum (Sorghum bicolor), wheat (Triticum aestivum) and their processed products retailed from various outlets in Nairobi County, Kenya. Qualitative assessment was done using thin layer chromatography (TLC) technique and quantified using HPLC-FD and UV-VIS spectrophotometry techniques. The study revealed that most cereals and their products are contaminated with OTA in the range of 0.1174±0.0385 – 3.0189±0.9452 ng/g. Highest contamination for cereals was recorded in samples from Gikomba market, while those from Nyamakima had the least contamination. In average, OTA levels in wheat grains retailed in Nairobi was 2.1478±0.3061 ng/g, which was higher than in sorghum (1.0311±0.0635 ng/g) and millet grains (0.6198±0.0315 ng/g). Finger millet flour and sorghum flour contained 0.6302±0.0203 and 07439±0.0254 ng/g, respectively. White wheat flour recorded lower levels, 0.1174±0.0385 ng/g, than whole wheat flour whose mean value was 0.6176±0.0445 ng/g. Whole wheat bread recorded an average mean of 0.9842±0.0904 ng/g, which was higher than that of white wheat bread (0.3475±0.0158 ng/g). The total mean OTA content in raw millet malt, roasted mixed brewers malt and local brew (busaa) was 0.7658±0.0192, 2.7544±0.0371 and 3.0189±0.9452 ng/g, respectively. These levels are lower than those found in studies from other countries. The levels of OTA in cereal grains and their processed products were found to be significantly different. The study outcomes provides documented evidence on OTA levels in Kenyan wheat, finger millet and sorghum grains, and their processed products, which can be used by the government agencies and relevant bodies to assess the health risk resulting from consumption of contaminated foodstuff.