Browsing by Author "Mahuku, George"

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    First evidence on the occurrence of multi-mycotoxins and dietary risk exposure to AFB1 along the cassava value chain in Uganda
    (Springer, 2024-11-30) Oyesigye, Elias; Cervini, Carla; Oluwakayode, Abimbola; Mahuku, George; Medina, Angel
    This study investigated the occurrence and distribution of multiple mycotoxins (aflatoxin B1, B2, G1, G2, fumonisins B1, B2, ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZEN), and citrinin (CIT)) in cassava products and as assessed the potential risk of aflatoxin B1 (AFB1) exposure among cassava consumers. A total of 192 samples of cassava products (96 flour and 96 chips, each with 48 samples from farmer and 48 from wholesaler) were analysed using LC/MS–MS. All positive samples irrespective of their origin (flour or chips) exhibited AFB1 levels exceeding the EU regulatory threshold of 5 µg/kg. The sum of fumonisins (FB1 + FB2), ZEN, and DON were significantly (P < 0.05) higher in cassava flour (14.3 µg/kg; 3.71 µg/kg; 25.1 µg/kg) compared to chips (6.54 µg/kg; 1.25 µg/kg; 0.25 µg/kg), respectively. Aflatoxins G2 was not detected in any of 192 samples. Cassava flour samples from farmers exhibited significantly (P < 0.05) higher mean concentrations of AFB1 (27.1 µg/kg), total aflatoxins (78.2 µg/kg), and ochratoxin A (79.6 µg/kg) in contrast to wholesalers, whose mean levels were notably lower at 8.91, 5.79 µg/kg, and 2.44 µg/kg, respectively, pointing the likely critical source of mycotoxin contamination. Cassava consumers in Northern Uganda are at a higher risk, with an estimated 2.06 cancer cases per 100,000 individuals per year compared to those in Eastern Uganda at 0.25. This study underscores the urgent need for interventions to manage aflatoxins in cassava flour, particularly at farm level in Northern Uganda. It accentuates a shift market to household-level sampling and the need for analytical methods targeting multiple mycotoxins.
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    Maize meal (posho) served at selected boarding schools in western Uganda is highly contaminated with aflatoxins
    (BRILL, 2024-01-16) Oyesigye, Elias; Nkurunungi, John Bosco; Mlahagwa, Wendo; Raymond, Amanya; Mahuku, George; Medina, Angel
    The study aimed to evaluate food handling practices and assess the maize-bean supply chain in selected boarding schools of western Uganda. Additionally, it sought to determine the extent of aflatoxin exposure in the maize-bean meal consumed by students within the age range of 5 to 24. A cross-sectional study was conducted in two districts of Bushenyi and Sheema to gather 95 samples (31 beans, 32 maize flour, and 32 cooked maize flour-posho). In addition, 262 individual interviews were conducted. The findings revealed that only 9.38% of the schools store food as per World Health Organisation standards. The majority of schools (57.9%) purchase maize flour and beans from any stockist with no contractual obligations (random supplier), and all the 32 schools base on visual parameters, especially white colour, and smell to rule out aflatoxin contamination. Maize flour stored on the ground registered significantly (P = 0.0018) higher levels (54.3 ± 10.1 μg/kg) of total aflatoxins than that stored on a raised platform (14.7 ± 2.6 μg/kg). Likewise, the supplier significantly influenced total aflatoxins levels (P = 0.0064), with higher levels (44.6 ± 8.0 μg/kg) detected in maize flour supplied by a random supplier than a pre-qualified one (14.7 ± 2.6 μg/kg). Given the low levels (1.3 to 2.8 μg/kg), which are far less than the Maximum Tolerated Limit (MTL) of 10 μg/kg, aflatoxins do not pose a significant problem in beans. Aflatoxins exposure in younger children (5-12 years) was higher (61.5 ng/kg bw/day) than in older ones (13-24 years; 41.5 ng/kg bw/day). Similarly, the risk of developing hepatocellular carcinoma was greater in younger children (1.84 cases per 100,000 people) compared to older ones (1.24 cases per 100,000 people). The findings underscore an urgent need to formulate guidelines for procurement, storage, and food handling in schools, alongside intensifying inspection programmes for food handling. Additionally, there is need to expand the research scope by incorporating a greater number of schools from varied geographical areas within Uganda, while rigorously monitoring the entirety of the food supply chain.
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    Potential impact of current agricultural practices on mycotoxin occurrence and mycotoxin knowledge along the cassava value chain in Uganda
    (Elsevier, 2024-09-01) Oyesigye, Elias; Cervini, Carla; Mahuku, George; Medina, Angel
    Cassava is the second most important staple food crop for Uganda and is prone to contamination with mycotoxins. This study aimed at understanding the current agricultural practices, their potential influence on mycotoxin occurrence, as well as assessing mycotoxin knowledge among key cassava value chain actors, including farmers, wholesalers, and processors. Data were collected through individual interviews (210), key informant interviews (34), and 4 focus group discussions. The findings revealed that 51% of farmers peeled cassava directly on bare ground, resulting in direct contact with soil that potentially harbors mycotoxin-producing fungi, such as Aspergillus section Flavi. During postharvest handling, 51.6% of farmers dried cassava chips directly on bare ground. Nearly, all (95.2%) of wholesalers packed cassava chips in local gunny bags and placed them on ground instead of pallets. In the processing of cassava chips into flour, only one of the 14 processing machines was certified by the Uganda National Bureau of Standards. Additionally, there was only one processing machine available for every 180 (1:180) consumers bringing their cassava for processing. 50.8% of cassava consumers interviewed admitted to consuming cassava flour regardless of quality, while 73% blended cassava flour with flour from mycotoxin-susceptible crops mainly maize, millet, and sorghum. Most (96.2%) of the people along the cassava value chain did not understand what the term mycotoxins meant. However, 56% of interviewed respondents were familiar with the term aflatoxins. Of the cassava value chain actors aware of mycotoxins, 82.9% knew of methods for reducing aflatoxin contamination, but only 40.9% were putting such methods into practice. More farmers (47.9%) managed aflatoxins compared to wholesalers (33.3%) and processors (21.4%). Knowledge on aflatoxins was significantly associated with value chain actor (P = 0.026), head of household (P = 0.004), region (P = 0.033), age (P = 0.001), and experience (P = 0.001). This study highlights the critical areas of mycotoxin contamination within the cassava value chain in Uganda and underscores the need to improve the knowledge among value chain actors especially farmers.