Browsing by Author "Mshanga, John"

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Effectiveness of complementary sorting methods in reducing aflatoxin contamination in groundnuts
(BRILL WAGENINGEN ACADEMIC, 2023-12-07) Mshanga, John; Makule, Edna; Ngure, Francis
Aflatoxin contamination of staple foods remains a public health concern in many tropical and sub-tropical countries. In sub-Saharan Africa, groundnuts are a significant source of aflatoxin (AF) in vulnerable populations such as infants and young children. However, there are limited scalable and affordable technological interventions to reduce the risk of aflatoxin ingestion in low and middle-income contexts. This study compared the effectiveness of complementary sorting methods in reducing AF contamination, time taken, and percentage loss of groundnuts. The study also evaluated bulk density and kernel weight as proxies for AF. Groundnuts were sampled from 19 bags at a medium-scale enterprise in Tanzania (Halisi) that processes cereal-based blended flours for complementary feeding. The samples were subjected to six sorting methods: (1) size (S) sorting, which yielded large and small fractions (n = 38); (2) density (D) sorting, which yielded heavy and light fractions (n = 38), (3) visual (V) sorting, (4) the combination of size and visual (SV), (5) the combination of density and visual (DV), and (6) the combination of size, density, and visual (SDV) which yielded grades 1, 2, 3, and 4 (n = 76). Samples of unsorted groundnuts and grades from all six sorting regimes (n = 418) were analysed for total aflatoxin by enzyme-linked immunosorbent assay. Analysis of variance (ANOVA) at a 5% significance level was used to compare AF reduction efficiency. Aflatoxin levels were reduced by 99% for the highest grade (G1) by the SDV sorting method. The SDV sorting method was the most effective in reducing AF contamination by removing 14% outsort (Grade 4) from 1 kg groundnut within 22 min. Bulk density and 100 kernels weight were inversely associated with AF, indicating their value as AF proxies. Scaling up such low-cost sorting methods can significantly reduce AF along the value chain and improve food safety
Modeling maize aflatoxins and fumonisins in a Tanzanian smallholder system: Accounting for diverse risk factors improves mycotoxin models
(PLOS One, 2025-01-13) Stafstrom, William; Ngure, Francis; Mshanga, John; Wells, Henry; Nelson, Rebecca; Mischler, John
Human exposure to mycotoxins is common and often severe in underregulated maize-based food systems. This study explored how monitoring of these systems could help to identify when and where outbreaks occur and inform potential mitigation efforts. Within a maize smallholder system in Kongwa District, Tanzania, we performed two food surveys of mycotoxin contamination at local grain mills, documenting high levels of aflatoxins and fumonisins in maize destined for human consumption. A farmer questionnaire documented diverse pre-harvest and post-harvest practices among smallholder farmers. We modeled maize aflatoxins and fumonisins as a function of diverse indicators of mycotoxin risk based on survey data, high-resolution geospatial environmental data (normalized difference vegetation index and soil quality), and proximal near-infrared spectroscopy. Interestingly, mixed linear models revealed that all data types explained some portion of variance in aflatoxin and fumonisin concentrations. Including all covariates, 2015 models explained 27.6% and 20.6% of variation in aflatoxin and fumonisin, and 2019 models explained 39.4% and 40.0% of variation in aflatoxin and fumonisin. This study demonstrates the value of using low-cost risk factors to model mycotoxins and provides a framework for designing and implementing mycotoxin monitoring within smallholder settings.
Physical Methods for Reduction of Aflatoxins Exposure in Groundnuts in Some Low-Income Countries: A Review
(Enviro Research Publishers, 2023-09-04) Mshanga, John; Makule, Edna; Ngure, Francis
Aflatoxin (AF) is a powerful carcinogen primarily produced by some strains of the fungus Aspergillus flavus and Aspergillus parasiticus, which frequently infest nuts and cereal crops. Groundnuts are among the most widely studied substrates of Aspergillus spp., growth and AF contamination. Aflatoxin contamination is a significant public health concern since chronic exposure is linked to causing carcinogenicity, teratogenicity, hepatotoxicity, estrogenicity, neurotoxicity, childhood growth impairment, and immunotoxicity in humans and animals. Acute exposure to AF contamination is associated with fatal aflatoxicosis due to nausea, vomiting, abdominal pain, and convulsions. Good agricultural practices, control of plant diseases, and favourable storage conditions can limit AF contamination yet do not guarantee complete elimination. Looking for an effective technique to reduce AF to an acceptable regulatory limit has been a great subject among researchers. Physical methods like manual visual sorting, screening, density, roasting, dehulling, winnowing, and decortication can reduce AF contamination while maintaining the quality of the kernel and render the kernels harmless to humans and animals compared to AF degradation by chemicals. Therefore, the present review article found that physical removal/visual sorting efficiently lowered the mean AF content commonly used in low-income countries. We briefly enumerated the effectiveness of various common physical methods in reducing post-harvest AF contamination in groundnuts, particularly their percentage AF reduction and outsort/loss, sufficient AF reduction evidence, feasibility, and scalability. We also highlighted the merits and demerits of these methods and essential information that could be helpful for further investigation