DETERMINATION OF LEVELS OF AFLATOXIN IN MAIZE SAMPLES: A CASE STUDY OF UASIN GISHU COUNTY

Abstract

The determination of levels of aflatoxins was done in Uasin Gishu County Kenya. Aflatoxins are compound produced by the two fungi; aspergillus flavus and aspergillus parasiticus. The main aflatoxins B1, B2, G1 and G2 have been detected in cereals. In Kenya outbreaks of maize poisoning was reported in Makueny County in 2004 and 2005. Twenty samples from every division were collected and pre and post-harvest farming practices were identified using questionnaire. At the market level, 15 samples per month were collected from various outlets for the 3 consecutive months; June, July and August. All samples were analyzed for the presents of aflatoxin using the TLC method, procedure used adopted from KEBS. Quantification of an aflatoxin was done using ELISA method. The four main types of aflatoxins B1, B2, G1 and G2 were detected an indication that the fungal A. parasiticus and A. flavus are present within the region. The results showed that in the whole county 49 out of 165 samples tested positive of aflatoxin, 36 from the farms and 13 from the market outlets. Ainabkoi division had aflatoxin mean level of 3.26 ppb as compared to other five divisions. Six samples tested positive of aflatoxin with the highest concentration of 21.90 ppb with minimum 4.40 ppb. 2 samples were above MTL. In Kesses division, among the twenty samples collected, 7 tested positive. The sample with the maximum aflatoxin concentration recorded was 11.20 ppb while the lowest was 1.60 ppb only 1 sample was above the MTL with divisional mean being 1.48 ppb. Moiben division had the highest number of positive samples (10 samples) which contributed to higher mean of 4.26 ppb. In Kapseret division, 8 samples tested positive and all samples which tested positive were below 10 ppb, the limit set by KEBS. The mean value recorded was 1.70 ppb with the highest concentration being 8.90 ppb and the lowest was 1.70 ppb. In soy division, only 3 samples tested positive with the mean of 0.68 ppb and all the 3 samples were within the recommended standard value. In Turbo division 4 samples tested positive but 2 samples had 10.60 ppb and 15.20 ppb which were above the limit recommended by KEBS. Divisional mean value was 1.91 ppb. From the samples collected from the market 13 out of 45 samples tested positive accounting for 27.2 %. Aflatoxin level over the three months found to be in order July with the respective values of 22.22 ppb, 17.60 ppb and 9.33 ppb. June had the sample with lowest concentration of 0.90 ppb while July had the sample with the highest concentration of 68.10 ppb. Ten factors causing aflatoxin contamination in maize was studied in the whole county and the data were analyzed using descriptive statistics the significant level within 0.5 to 1.5. Sorting, storage method, clean storage device, granary use and use of pesticide were within this range. ANOVA confirmed that there was significant difference in the test results and also in aflatoxin concentration; the F-ratio was 1.649 which was above 1 when confidence level of 95 % was used. For the post-hog test analysis considering the mean difference at the 0.05 and 0.1 levels confirmed that there was a relationship within the county in pre and post-harvest practices and also aflatoxin concentration. Levene‟s and t-test results agreed with some of the tested variables in aflatoxin contamination because p-values obtained were above the critical value of 0.05