Influence of Different Altitudes Maize Harvest Seasons and Storage and Pre-Storage Practices on Aflatoxin Ocurrence among Households in Makueni County, Kenya

Abstract

Aflatoxicosis resulting from consumption of highly contaminated maize poses a challenge to public health as outbreaks have occurred in a number of countries including Kenya. It is caused by aflatoxins which are secondary metabolites from mould of the Aspergillus species that include among others Aspergillus parasiticus and Aspergillus flavus. Fungal spoilage and aflatoxin contamination have been known to be of major concern in cereals and other foodstuffs including maize. The main objective of the study was to determine the influence of maize storage and pre-storage practices on aflatoxin occurrence among maize stored in households in Makueni County which had previously experienced aflatoxicosis outbreaks. Aflatoxin levels of maize harvested in different altitudes and different seasons were also compared. The design of the study, which was conducted in Kibwezi and Kilome sub-counties of Makueni County, was comparative analytical study. Two different sites were selected for this study in which 240 households from each site were enrolled in the study. Data was collected using questionnares, observation checklists, and focus group discussions. Maize samples were collected from sub-sampled households for analysis of aflatoxin. Results showed that maize harvested in first season had higher moisture content (12.9%) and aflatoxin positivity (25.0%) in lower altitude area than higher altitude area which had 12.8% and 4.2%, respectively. Maize harvested in second season had higher moiture content (13.6%) and aflatoxin positivity (33.3%)) in lower altitude area than maize harvested in higher altitude area which had 13.5% and 12.5%, respectively. Maize harvested in second season had higher moiture content and aflatoxin positivity than maize harvested in first season. The most common sub-types of aflatoxin affecting maize were AFB1 and AFB2. Over 70% of households’ stored their maize in raised wooden platforms with some storing in traditional cribs. Storage of maize in bags directly on the floor had higher aflatoxin positivity in low altitude area at 33.3% and 37.5% for first and second season, respectively. Certain maize pre-storage practices such as length of stay of maize in field before harvest and duration of drying were found to be associated with aspects of aflatoxin contamination of maize (P<0.05). Similarly, maize storage practices including storage time, proper storage, frequency of store cleaning were associated with mould and insect pests infestation, discolouration and aflatoxin occurrence in maize (P<0.05). Moisture content was negatively correlated with aflatoxin occurrence. The results of this study will help in development of better policies and strategies of reducing aflatoxin contamination of maize and resultant aflatoxicosis. As maize consumers are likely to be exposed to risk of aflatoxicosis, there is need for government authorities to regularly monitor levels of aflatoxin contamination of household maize for timely intervention should afatoxin exceed permissible levels of 10 ug/kg set by regulatory authorities. Further research is recommended to determine the effects of household specific storage and pre-storage practices on aflatoxin contamination of maize in other different regions and seasons.