Aflatoxin Contamination and Consumer Valuation of Maize in Western Kenya

Crop Production/Industries,

The importance of market signals in crop varietal development: Lessons from Komboka rice variety

Growing high-yielding varieties is crucial for successful crop production and maximizing farmers’ net returns. One such example is IR05N221, locally referred to as Komboka rice variety, which was released in Kenya in 2013. On the one hand, Komboka can bridge the gap in rice imports since yields of existing rice varieties do not meet the increasing rice consumption levels of the Kenyan population. On the other hand, it has taken about seven years for Komboka to be appreciated by farmers, necessitating the need to understand farmer preferences when it comes to adopting a new improved variety. We used a mixed-method study approach by combining quantitative and qualitative data collected regionally and locally in both rainfed and irrigated ecologies. When compared to most of the other rice varieties under evaluation, Komboka was high-yielding, early-maturing, and had moderate tolerance to diseases in both rainfed and irrigated ecologies. However, farmers at the regional level ranked Komboka either at the same or lower rank in terms of sensory attributes. At the local level, farmers predominantly grew older and more aromatic Basmati 370 rice variety for sale, as it fetched them more money, with preferences for both men and women rice farmers being the same. Despite Komboka being a high-yielding variety, Mwea rice farmers’ perceptions and preferences for this improved variety were low. While Komboka was equally aromatic, the lack of a ready market dissuaded these farmers from widely preferring the new Komboka variety. We provide prerequisite information that can support the commercialization and promotion of the Komboka variety. We also show that widespread favourable perception of new varieties hinges on matching preferences between breeders’ efforts for improved rice productivity with farmers’ needs for market competitiveness in these new varieties

Multi-spectral kernel sorting to reduce aflatoxins and fumonisins in Kenyan maize

Maize, a staple food in many African countries including Kenya, is often contaminated by toxic and carcinogenic fungal secondary metabolites such as aflatoxins and fumonisins. This study evaluated the potential use of a low-cost, multi-spectral sorter in identification and removal of aflatoxin- and fumonisin-contaminated single kernels from a bulk of mature maize kernels. The machine was calibrated by building a mathematical model relating reflectance at nine distinct wavelengths (470–1550\ua0nm) to mycotoxin levels of single kernels collected from small-scale maize traders in open-air markets and from inoculated maize field trials in Eastern Kenya. Due to the expected skewed distribution of mycotoxin contamination, visual assessment of putative risk factors such as discoloration, moldiness, breakage, and fluorescence under ultra-violet light (365\ua0nm), was used to enrich for mycotoxin-positive kernels used for calibration. Discriminant analysis calibration using both infrared and visible spectra achieved 77% sensitivity and 83% specificity to identify kernels with aflatoxin >10\ua0ng\ua0g and fumonisin >1000\ua0ng\ua0g, respectively (measured by ELISA or UHPLC). In subsequent sorting of 46 market maize samples previously tested for mycotoxins, 0–25% of sample mass was rejected from samples that previously tested toxin-positive and 0–1% was rejected for previously toxin-negative samples. In most cases where mycotoxins were detected in sorted maize streams, accepted maize had lower mycotoxin levels than the rejected maize (21/25 accepted maize streams had lower aflatoxin than rejected streams, 25/27 accepted maize streams had lower fumonisin than rejected streams). Reduction was statistically significant (p\ua

Insights Into The Genetic And Environmental Bases Of Mycotoxin Contamination In Kenyan Maize

Mycotoxins are toxic fungal secondary metabolites that contaminate an estimated 25% of foods globally. Aflatoxin and fumonisin are major mycotoxins that contaminate maize in tropical countries. Kenya's frequent aflatoxicosis outbreaks and the associated human fatality rates have received global attention. The objective of this dissertation was to investigate the extent and the drivers for mycotoxin contamination in Kenyan maize. Between May 2009 and March 2010, surveys were conducted in three provinces (Rift Valley, Western and Nyanza) of western Kenya, the country's grain basket and a region where mycotoxin outbreak had not been recognized. Aflatoxin contamination above the regulatory limit of 10 ppb was observed in 15% of the flour samples that had been collected from the patrons of local mills. Drought and monocropping were identified as drivers for increased aflatoxin contamination. A longitudinal survey in farmers' storage sheds and at local mills in Western Province revealed vulnerability of the most popular varieties to mycotoxins. Surveys were conducted in 10 districts of Eastern Province during an aflatoxin outbreak in 2010. Aflatoxin contamination above 10 ppb was observed in 39% of the flour samples from patrons (n=1500) of local mills, while 37% were above the 1 ppm regulatory limit for fumonisin. Reduced aflatoxin accumulation was associated with intercropping, larger farms and high grain yield. Visual grain sorting reduced fumonisin but not aflatoxin levels. Analysis of aflatoxin in naturally-infected diverse maize germplasm grown in eastern Kenya showed higher contamination under low nitrogen (N) than under optimal N. Early-maturing maize had reduced aflatoxin accumulation under low N, possibly because of faster utilization of the limiting and diminishing soil N. A mature kernel screening assay of diverse maize inbred lines showed that colonization and aflatoxin accumulation were influenced by the ear environment (where maize were grown). High sulfur content in grain was associated with reduced kernel colonization and aflatoxin accumulation. Management strategies should include: 1. surveillance across all maize-producing regions, 2. breeding for early maturing maize, and 3. spectral grain sorting. Experiments should be conducted to identify the intercrop species and the mechanism for aflatoxin control, and to elucidate the maize ionome - mycotoxin relationship. ii

Enhancing Food Safety through Adoption of Long-Term Technical Advisory, Financial, and Storage Support Services in Maize Growing Areas of East Africa

Grain production and storage are major components in food security. In the ancient times, food security was achieved through gathering of fruits, grains, herbs, tubers, and roots from the forests by individual households. Advancements in human civilization led to domestication of crops and a need to save food for not only a household, but the nation. This extended need for food security led to establishment of national reservoirs for major produces and this practice varies greatly in different states. Each of the applied food production, handling, and storage approaches has its benefits and challenges. In sub-Saharan Africa, several countries have a public funded budget to subsidize production costs, to buy grains from farmers, and to store the produce for a specific period and/or until the next harvests. During the times of famine, the stored grains are later sold at subsidized prices or are given for free to the starving citizens. If there is no famine, the grain is sold to retailers and/or processors (e.g., millers) who later sell it to the consumers. This approach works well if the produce (mainly grain) is stored under conditions that do not favor growth of molds, as some of these microbes could contaminate the grain with toxic and carcinogenic metabolites called mycotoxins. Conditions that alleviate contamination of grains are required during production, handling, and storage. Most of the grain is produced by smallholder farmers under sub-optimal conditions, making it vulnerable to colonization and contamination by toxigenic fungi. Further, the grain is stored in silos at large masses, where it is hard to monitor the conditions at different points of these facilities, and hence, it becomes vulnerable to additional contamination. Production and storage of grain under conditions that favor mycotoxins poses major food health and safety risks to humans and livestock who consume it. This concept paper focuses on how establishment of a local grain production and banking system (LGPBS) could enhance food security and safety in East Africa. The concept of LGPBS provides an extension of advisory and finance support within warehouse receipt system to enhance grain production under optimal conditions. The major practices at the LGPBS and how each could contribute to food security and safety are discussed. While the concept paper gives more strength on maize production and safety, similar practices could be applied to enhance safety of other grains in the same LGPBS

Aflatoxin Contamination of Maize in Kenya: Observability and Mitigation Behavior

Using a unique dataset of maize samples and consumer interviews form Eastern Kenya, we find that the presence of the fungal contaminant aflatoxin is negatively associated with the use of maize flour for food. While food remains the most common use of maize regardless of the presence of the toxin, contaminated maize is relatively more likely to be used for the production of alcoholic beverages, livestock feed, or sale. Retail maize prices are strongly correlated with an easily observable quality attribute, discoloration, but the correlation between price and aflatoxin contamination is not statistically distinguishable from zero. This suggests that consumers observe attributes that are correlated with aflatoxin upon careful inspection, or perhaps consumption of a portion of maize from a particular batch, and that their use of flour is based on this information. The apparently limited observability of attributes associated with aflatoxin contamination implies that problems associated with asymmetric information may affect this market. A comparison of maize quality by source provides evidence of such problems: purchased maize is more likely to be contaminated with aflatoxin than maize households have grown themselves, despite the fact that maize from larger producers is less likely to be contaminated

Asymmetric Information and Food Safety: Maize in Kenya

When quality is not observable by prospective buyers, theory predicts that the quality of marketed goods will suffer, and the volume of trade will be depressed. Using data from more than 2,000 maize samples collected in four Kenyan provinces, we show that the presence of aflatoxin, an invisible and dangerous fungal contaminant, is not reflected in maize prices but does affect how maize is used. This apparent market failure reduces the quality of maize available on the market. In addition, we show that self-produced maize is a normal good