Effect of Aspergillus flavus fungi infection and aflatoxin contamination on single corn kernel mechanical strength

Authors: YAO, HAIBO - Mississippi State University; HRUSKA, ZUZANA - Mississippi State University; KINCAID, RUSSELL - Mississippi State University; TAO, FEIFEI - Mississippi State University; Rajasekaran, Kanniah - Rajah

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2023
Publication Date: 3/14/2023
Citation: Yao, H., Hruska, Z., Kincaid, R., Tao, F., Rajasekaran, K. 2023. Effect of Aspergillus flavus fungi infection and aflatoxin contamination on single corn kernel mechanical strength. Applied Engineering in Agriculture. 39(2):197-205. https://doi.org/10.13031/aea.15266.
DOI: https://doi.org/10.13031/aea.15266

Interpretive Summary: Aflatoxin contamination of corn kernels poses a major health concern because of its carcinogenic nature in addition to reducing the marketability of the commodity in world markets. Identification and removal of affected kernels will be highly beneficial in this regard. Kernels infected with Aspergillus flavus often show a loss of seed integrity, whether the infection is visible or not. The reduction in kernel strength was measured as a possible mechanism to identify infected kernels. Kernels infected with toxin-producing or non toxin-producing strains of the fungus were compared to non-infected controls. Compared to controls, the fungal treated kernels showed reduced kernel strength and it was very prominent in kernels treated with the non-toxin producing strain. It is possible that the fungal growth per se may be the determinant factor in reducing the kernel strength. However, kernels with high aflatoxin levels (>300 ppb) were invariably weaker than the other treatments. Results from this study provide new information on sorting and identifying contaminated kernels thus helping in mitigation strategies for post-harvest management of aflatoxin contamination in corn.

Technical Abstract: US corn production reached an all-time high of 15.1 billion bushels in 2016. One persistent food safety issue associated with corn is aflatoxin contamination. Because of the carcinogenic and immunosuppressive nature of aflatoxins, aflatoxin contamination is a major health threat for consumers of affected grains and is costly to the food and feed industry. The Federal Drug Administration has published stringent regulations on allowable aflatoxins levels in grains intended for humans (20 ppb) and for large animals (100 ppb). Aflatoxins are secondary metabolites produced mainly by the fungi Aspergillus flavus and A. parasiticus. Under environmental conditions suitable for fungal growth and aflatoxin production, these fungi are capable of infecting corn ears in the field and corn kernels in storage. When corn kernels are infected, the fungi use nutrients from the kernels to grow and propagate. In general, moldy and contaminated kernels are discolored and lighter in weight. These features could aid in identifying and removal of the infected kernels. The objective of this study was to investigate the relationship between the mechanical strength of corn kernels and fungal infection, as well as aflatoxin contamination as a consequence of fungal infection. In this study, corn kernels were infected with aflatoxin producing (AF13) and non-toxin-producing (AF36) A. flavus strains in from lab inoculations. A total of 900 kernels were assigned to three groups, non-inoculated control, AF13-inoculated, and AF36-inoculated. One hundred kernels from each group were incubated for 3, 5, and 8 days. At the end of incubation, each kernel was cleaned and dried. Compression rupture force (CRF) of each kernel was measured to assess its kernel strength. The results show that kernel strength was significantly different among the three fungal treatment groups, with the control kernels being the strongest and the AF36-inoculated kernels the weakest. The results also indicated that kernels with aflatoxin contamination of 300 ppb and above were significantly weaker than other kernels. It is expected that the results of this research could benefit the corn industry by mitigating and eliminating the aflatoxin contamination problem in post-harvest management.