Aflatoxin in cereals and groundnut from small holder farming households in Malawi.

Aflatoxin contamination in commonly consumed cereals and nuts may place children at higher risk of stunting and adults at risk of developing liver cancer. This study investigated knowledge on aflatoxins and the level of aflatoxin B1 contamination in commonly consumed cereals and nuts in Malawi. It also included an examination of the proportion of cereals and nuts contaminated above regulatory maximum limits. Aflatoxin contamination in samples was assessed using an enzyme-linked immunosorbent assay (ELISA) method. Less than half of all households knew that consumption of aflatoxin contaminated grain is associated with stunting and lowered immunity. Sorghum samples were the most contaminated and millet the least contaminated. Aflatoxin contamination was highest in southern Malawi and least in northern Malawi. Observed results indicate that this population is at risk of poor health due to lack of knowledge and aflatoxin exposure. Strategies to address contamination should therefore include a comprehensive education campaign to increase knowledge and promote accessible strategies.

Knowledge, Attitude and Practice of Malawian Farmers on Pre- and Post-Harvest Crop Management to Mitigate Aflatoxin Contamination in Groundnut, Maize and Sorghum-Implication for Behavioral Change.

A knowledge, attitude and practice (KAP) study was conducted in three districts of Malawi to test whether the training had resulted in increased knowledge and adoption of recommended pre- and post-harvest crop management practices, and their contribution to reducing aflatoxin contamination in groundnut, maize and sorghum. The study was conducted with 900 farmers at the baseline and 624 farmers at the end-line, while 726 and 696 harvested crop samples were collected for aflatoxin testing at the baseline and end-line, respectively. Results show that the knowledge and practice of pre- and post-harvest crop management for mitigating aflatoxin were inadequate among the farmers at the baseline but somewhat improved after the training as shown at the end-line. As a result, despite unfavorable weather, the mean aflatoxin contamination level in their grain samples decreased from 83.6 to 55.8 ppb (p < 0.001). However, it was also noted that increased knowledge did not significantly change farmers' attitude toward not consuming grade-outs because of economic incentive incompatibility, leaving potential for improving the practices further. This existing gap in the adoption of aflatoxin mitigation practices calls for approaches that take into account farmers' needs and incentives to attain sustainable behavioral change.

A Critical Review of Aflatoxin Contamination of Peanuts in Malawi and Zambia: The Past, Present, and Future.

Peanut (Arachis hypogaea L.) is an important crop in Malawi and Zambia. The crop is valued for soil improvement in cereal-based cropping systems, for improving the livelihoods of farming households who consume it and also sell it for cash, and for earning foreign exchange when exported. Research and development efforts have resulted in an increase in both peanut production area and productivity. However, a key challenge that still needs to be solved in these countries is how to produce peanuts with acceptable levels of aflatoxin contamination. Data continues to show that aflatoxin continues to be a problem in both formal and informal trade. As a result, unlike 30 years ago, most of the peanut trade has now shifted to domestic and regional markets that do not restrict the sale of aflatoxin-contaminated peanuts. Impacts of aflatoxin contamination on health and also on the full cost burden of control are not well documented. Technologies are available for mitigating against aflatoxin contamination. The advantages, disadvantages, and gaps associated with these technologies are discussed. Considerable money and effort continues to be invested in Malawi and Zambia into mitigating aflatoxin contamination, but evidence of long-term success is limited. Based on past and current initiatives, the prospects of eliminating aflatoxin in the near future at the household level and in trade are not promising.

Aflatoxin B1 levels in groundnut products from local markets in Zambia.

In Zambia, groundnut products (milled groundnut powder, groundnut kernels) are mostly sold in under-regulated markets. Coupled with the lack of quality enforcement in such markets, consumers may be at risk to aflatoxin exposure. However, the level of aflatoxin contamination in these products is not known. Compared to groundnut kernels, milled groundnut powder obscures visual indicators of aflatoxin contamination in groundnuts such as moldiness, discoloration, insect damage or kernel damage. A survey was therefore conducted from 2012 to 2014, to estimate and compare aflatoxin levels in these products (n = 202), purchased from markets in important groundnut growing districts and in urban areas. Samples of whole groundnut kernels (n = 163) and milled groundnut powder (n = 39) were analysed for aflatoxin B1 (AFB1) by competitive enzyme-linked immunosorbent assay (cELISA). Results showed substantial AFB1 contamination levels in both types of groundnut products with maximum AFB1 levels of 11,100 µg/kg (groundnut kernels) and 3000 µg/kg (milled groundnut powder). However, paired t test analysis showed that AFB1 contamination levels in milled groundnut powder were not always significantly higher (P > 0.05) than those in groundnut kernels. Even for products from the same vendor, AFB1 levels were not consistently higher in milled groundnut powder than in whole groundnut kernels. This suggests that vendors do not systematically sort out whole groundnut kernels of visually poor quality for milling. However, the overall contamination levels of groundnut products with AFB1 were found to be alarmingly high in all years and locations. Therefore, solutions are needed to reduce aflatoxin levels in such under-regulated markets.

A Case for Regular Aflatoxin Monitoring in Peanut Butter in Sub-Saharan Africa: Lessons from a 3-Year Survey in Zambia.

A 3-year comprehensive analysis of aflatoxin contamination in peanut butter was conducted in Zambia, sub-Saharan Africa. The study analyzed 954 containers of 24 local and imported peanut butter brands collected from shops in Chipata, Mambwe, Petauke, Katete, and Nyimba districts and also in Lusaka from 2012 to 2014. For analysis, a sample included six containers of a single brand, from the same processing batch number and the same shop. Each container was quantitatively analyzed for aflatoxin B1 (AFB1) in six replicates by using competitive enzyme-linked immunosorbent assay; thus, aflatoxin contamination level of a given sample was derived from an average of 36 test values. Results showed that 73% of the brands tested in 2012 were contaminated with AFB1 levels >20 µg/kg and ranged up to 130 µg/kg. In 2013, 80% of the brands were contaminated with AFB1 levels >20 µg/kg and ranged up to 10,740 µg/kg. Compared with brand data from 2012 and 2013, fewer brands in 2014, i.e., 53%, had aflatoxin B1 levels >20 µg/kg and ranged up to 1,000 µg/kg. Of the eight brands tested repeatedly across the 3-year period, none consistently averaged ≤20 µg/kg. Our survey clearly demonstrates the regular occurrence of high levels of AF B1 in peanut butter in Zambia. Considering that some of the brands tested originated from neighboring countries such as Malawi, Zimbabwe, and South Africa, the current findings provide a sub-Saharan regional perspective regarding the safety of peanut butter.

Knowledge, attitude, and practices concerning presence of molds in foods among members of the general public in Malawi.

This study assessed knowledge, attitude, and practices (KAP) of the public in Malawi on issues related to molds in foodstuffs. A survey involving structured questionnaire was conducted with 805 respondents from seven districts of Malawi. Descriptive statistics, t tests, and analyses of variance were calculated. A majority of respondents recognized that molds were dangerous to human health (88%); however, about 50% of respondents were not informed that mold toxins are thermally stable and that they are not destroyable by normal cooking processes. About 33% of the respondents asserted that they buy moldy maize, while approximately 20% of respondents reported that they consume moldy fruits having discarded moldy fraction. There were significant differences in knowledge scores among different demographic groups. Females had significantly (p < 0.05) lower knowledge scores on issues related to molds in foods. Additionally, the respondent's location had a significant effect. However, respondent's education had subtle effect on knowledge score and the overall population's knowledge score was generally low (3.55 ± 1.32 score out of 9). Results of the study underline the need to raise public's knowledge about health risks associated with spoilage molds in food and prevention and management options.

Uncommon occurrence ratios of aflatoxin B1, B 2, G 1, and G 2 in maize and groundnuts from Malawi.

We report an unusual aflatoxin profile in maize and groundnuts from Malawi, with aflatoxin G1 found routinely at equal or even higher levels than aflatoxin B1. Aflatoxin B1 (AFB1) ratio in a contaminated sample is generally greater than 50% of total aflatoxin (sum of aflatoxin B1, B2, G1, and G2). In Malawi, the aflatoxin occurrence ratios were determined by examining LC-MS/MS and HPLC fluorescence detection (FLD) data of 156 naturally contaminated raw maize and 80 groundnut samples collected in 2011 and 2012. Results showed that natural aflatoxin occurrence ratio differed. In 47% of the samples, the concentration of AFG1 was higher than that of AFB1. The mean concentration percentages of AFB1/AFB2/AFG1/AFG2 in reference to total aflatoxins were found to be 47:5:43:5%, respectively. The AFG1 and AFB1 50/50 trend was observed in maize and groundnuts and was consistent for samples collected in both years. If the AFB1 measurement was used to check compliance of total aflatoxin regulatory limit set at 10, 20, 100, and 200 µg/kg with an assumption that AFB1≥50% of the total aflatoxin content, 8, 13, 24, and 26% false negative rates would have occurred respectively. It is therefore important for legislation to consider total aflatoxins rather than AFB1 alone.

Comparison of Crop Rotation for Verticillium Wilt Management and Effect on Pythium Species in Conventional and Organic Strawberry Production.

The effects of broccoli and lettuce rotations on population densities of Verticillium dahliae and Pythium spp. in soil and on strawberry (Fragaria × ananassa) growth, yield, and Verticillium wilt were evaluated in conventional and organic production systems in California for 2 years. Under both management systems, strawberry was planted after two successive crops of broccoli or lettuce. The control treatment in the conventional field was strawberry planted in soils fumigated with methyl bromide + chloropicrin. Preplant densities of V. dahliae and Pythium sp. did not differ in these fields. At the end of the second broccoli crop, V. dahliae densities in conventional plots had declined by 44% in both years. In contrast, after the second broccoli crop, densities in organic fields decreased 47% in 2000 and 25% in 2001. In general, there were no differences in V. dahliae inoculum densities in organic and conventional plots following lettuce rotations. After the second vegetable production cycle, population densities of V. dahliae in broccoli rotated organic (24 CFU/g of soil in 2000 and 27 CFU/g of soil in 2001) or conventional (23 CFU/g of soil in 2000 and 19 CFU/g of soil in 2001) fields were significantly lower than those in lettuce rotated organic (40 CFU/g of soil in 2000 and 42 CFU/g of soil in 2001) or conventional (39 CFU/g of soil in 2000 and 35 CFU/g of soil in 2001) fields. However, crop rotation treatments had no consistent effect on the inoculum densities of Pythium spp. Canopy diameters of strawberry plants grown in rotation with broccoli were not different from those in fumigated control plots, whereas those from lettuce plots were 10% smaller. Strawberry plant nutrient analysis showed that fertilizer inputs into organic or conventional production were not responsible for the observed differences in plant size. Increases in strawberry yields were not consistent between years. Verticillium wilt incidence on strawberry was 12 to 24% lower in fields rotated with broccoli compared with fields rotated with lettuce. Wilt severity on strawberry was 22 to 36% lower in fields rotated with broccoli compared with those rotated with lettuce. The strategy of using broccoli rotation coupled with postharvest incorporation of broccoli residue continues to show promise as a tool in the management of Verticillium wilt in both conventional and organic strawberry production systems.

Effect of Incorporation of Brassica spp. Residues on Population Densities of Soilborne Microorganisms and on Damping-off and Fusarium Wilt of Watermelon.

Incorporating Brassica spp. residue to reduce populations of soilborne fungi and manage damping-off and Fusarium wilt of watermelon (Citrullus lanatus var. lanatus) was studied in two field experiments. Treatments included incorporating flowering Brassica napus cv. Dwarf Essex canola or B. juncea cv. Cutlass mustard and laying black polyethylene mulch at incorporation or 1 month after incorporation, methyl bromide, and a nontreated control. In both years, glucosinolates were identified and quantified in the shoots and roots of the flowering plants. In both years, the total concentration of glucosinolates incorporated per square meter was significantly higher for B. juncea than for B. napus. Isothiocyanates were inconsistently detected in the amended soils and none were detected more than 12 days postincorporation. After incorporation in 2004 and 2005, amended plots had higher populations of Fusarium oxysporum and Pythium spp. than the methyl bromide treatment, and in some treatments, populations were higher than in the control. Fluorescent Pseudomonas spp. were not suppressed in amended soils, and their populations were significantly higher in some amended treatments than those in methyl bromide-treated soils or nontreated control soils. Incidence of damping-off and severity of Fusarium wilt on seedless watermelon cv. Tri-X 313, which is susceptible to Fusarium wilt, were not consistently lower in brassica-amended soils or methyl bromide-treated plots than in nontreated control plots. Therefore, under spring conditions and methods used in this study, neither biofumigation nor methyl bromide fumigation in coastal South Carolina was an effective disease management tool for two soilborne pathogens of watermelon.