Articles
Fungal growth and aflatoxin contamination on sweetpotato stored under controlled atmosphere conditions
Article number
1456_37
Pages
285 – 292
Language
English
Abstract
Effective control of fungal growth in sweetpotato during postharvest storage is important to minimise disease incidence and potential production of mycotoxins, which pose risk to human health.
This study evaluated fungal disease dynamics and associated aflatoxin contamination in sweetpotato (cultivar ‘06-52’) stored for 12 weeks at 20°C under three different conditions, namely, i) continuous controlled atmosphere (CA) (5 kPa CO2 and 8 kPa O2), ii) air storage (0.003 kPa CO2 and 21 kPa O2), and iii) CA supplemented with 0.001 kPa ethylene.
Disease incidence during storage was evaluated cumulatively at 6-week intervals across sweetpotato root sections (proximal, middle, and distal). Fungal count was assessed using serial dilution plating on Potato Dextrose Agar (PDA) and Dichloran-Glycerol Agar (DG18). Isolated fungal spores were sub-cultured and analyzed for mycotoxins.
Results showed that after 12 weeks, disease incidence was higher at the proximal section, with decay levels doubling those at the distal section, reaching 12.3% under ethylene-supplemented CA and 12.8% under air storage.
The middle section had the lowest incidence, at 1.8 and 2.4%, respectively.
Ethylene-supplemented CA significantly increased fungal count, elevating it six-fold to 40.3±1.6 cfu mg‑1 at the proximal section compared to air storage on DG-18, and two-fold on PDA. Among the mycotoxins detected, Aflatoxin G1 was the most predominant, reaching 105.4 ng g‑1 (distal section, ethylene-supplemented CA) and 94 ng g‑1 (distal section, air storage). Continuous CA was highly effective in limiting aflatoxin contamination.
These findings provide valuable insights for designing effective storage strategies to mitigate fungal growth and associated aflatoxin contamination, thereby reducing postharvest losses and improving food safety.
Further investigation is needed to understand the biochemical mechanisms underlying spatial variations in fungal development during sweetpotato storage.
This study evaluated fungal disease dynamics and associated aflatoxin contamination in sweetpotato (cultivar ‘06-52’) stored for 12 weeks at 20°C under three different conditions, namely, i) continuous controlled atmosphere (CA) (5 kPa CO2 and 8 kPa O2), ii) air storage (0.003 kPa CO2 and 21 kPa O2), and iii) CA supplemented with 0.001 kPa ethylene.
Disease incidence during storage was evaluated cumulatively at 6-week intervals across sweetpotato root sections (proximal, middle, and distal). Fungal count was assessed using serial dilution plating on Potato Dextrose Agar (PDA) and Dichloran-Glycerol Agar (DG18). Isolated fungal spores were sub-cultured and analyzed for mycotoxins.
Results showed that after 12 weeks, disease incidence was higher at the proximal section, with decay levels doubling those at the distal section, reaching 12.3% under ethylene-supplemented CA and 12.8% under air storage.
The middle section had the lowest incidence, at 1.8 and 2.4%, respectively.
Ethylene-supplemented CA significantly increased fungal count, elevating it six-fold to 40.3±1.6 cfu mg‑1 at the proximal section compared to air storage on DG-18, and two-fold on PDA. Among the mycotoxins detected, Aflatoxin G1 was the most predominant, reaching 105.4 ng g‑1 (distal section, ethylene-supplemented CA) and 94 ng g‑1 (distal section, air storage). Continuous CA was highly effective in limiting aflatoxin contamination.
These findings provide valuable insights for designing effective storage strategies to mitigate fungal growth and associated aflatoxin contamination, thereby reducing postharvest losses and improving food safety.
Further investigation is needed to understand the biochemical mechanisms underlying spatial variations in fungal development during sweetpotato storage.
Authors
L.S. Magwaza, S. Sowe, A. Medina, R. Tosetti, S. Landahl, M.C. Alamar, L.A. Terry
Keywords
Aspergillus, ethylene, food loss, food safety, Fusarium, Ipomoea batatas, Penicillium, postharvest pathogens
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