Occurrence Of Aflatoxin Contamination On Maize In The Lower Eastern Kenya And Evaluation Of Superabsorbent Polymers In Its Management

Abstract

Food and feed safety has been a major concern in most countries in the recent times as more knowledge is being generated on the occurrence of natural toxins in foodstuffs and edible plant species. Among the natural toxins, aflatoxins have been given more attention due to their hazardous effects to animals and human beings. A study was conducted on aflatoxin contamination in maize samples collected from lower eastern counties in Kenya. The maize samples were collected through a survey that was conducted in Kitui, Machakos and Makueni counties where aflatoxin contaminations has been a perennial problem. The samples were cultured in czapek dox agar to get the fungal contaminants and the rest analyzed for aflatoxin contamination in the laboratory using liquid chromatography and mass spectrometry (LCMS). A further study of drying maize using super absorbent polymers (SAPS) was carried out in the laboratory. The desiccants were used in varied ratios of SAP: Maize, whereby the SAP was embedded in a membrane to avoid it mixing up with the maize. The ratios used included 1:1, 1:5, 1:10, 1:20 and control where no SAP was used. The experiment was carried out in three replicates and in different temperatures of 20°C, 30°C and 40°C and frequency change of hydrogels of 24 hours and 48 hours. After 216 hours, the maize samples were ground and aflatoxin concentration analyzed through LC-MS. The results from the questionnaire indicated that post harvest handling of maize predisposes grains to aflatoxin contamination. Among the Aspergillus spp isolated, Aspergillus niger constituted 50 % and Aspergillus flavus at 45% of the total isolates across the counties. In the LC-MS analysis 76% and 65% of samples had total aflatoxin levels below 20 ppb and 10 ppb leaving 24% and 35% of samples having total aflatoxin levels above 20 ppb and 10 ppb respectively. The 20ppb and 10ppb aflatoxin concentration are maximum limits recommended by World Health Organization (WHO) Kenya Bureau of Standards (KEBS) respectively. Results from maize drying experiment indicated that the ratio 1:1 had no aflatoxin concentration and ratio 1:5 had low concentration of aflatoxin of less than 10 ppb in all treatments. The control had high concentration of aflatoxin above 10 ppb in all treatments and 1:10 and 1:20 had aflatoxin levels dependent on temperature and frequency change of hydrogels. There was a significant drop of aflatoxin concentration in ratio 1:10 and 1:20 in both frequency change of hydrogel compared to where hydrogel was not changed. It was noted that temperature, moisture content, amount of (Super absorbent polymers) SAP used and time taken to dry maize influenced the drying rate and overall aflatoxin contamination. The study revealed that use of 1:1 ratio can dry maize and avoid aflatoxin contamination, other ratios can also be used but with regular change of hydrogels in 24 or 48 hours to achieve lower contamination of aflatoxin of less than 10 ppb.