Effect of Aspergillus Flavus Fungi Infection and Aflatoxin Contamination on Single Corn Kernel Mechanical Strength

Abstract

HighlightsKernels were artificially inoculated with toxigenic and non-toxigenic strains of Aspergillus flavus in the lab.Corn kernel mechanical strength was assessed as single kernel compression rupture force (CRF).Fungus-infected kernels had lower mechanical strength than the controls.Kernels with high aflatoxin contamination had lower mechanical strength than others.ABSTRACT. One persistent food safety issue associated with corn is aflatoxin contamination. Aflatoxins are secondary metabolites produced mainly by the fungi Aspergillus flavus (A. flavus) and A. parasiticus. Under environmental conditions suitable for fungal growth and aflatoxin production, these fungi are capable of infecting corn kernels in the field and 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 the identification and removal of infected kernels. The objective of this research 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. Corn kernels were infected with aflatoxin producing (AF13) and non-toxin-producing (AF36) A. flavus strains in 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. After incubation each kernel was cleaned and dried, then subjected to a destructive mechanical test. The compression rupture force (CRF) of each kernel was measured using a Mark-10 material test gauge to assess its kernel strength. The results show that kernel strength was significantly different between the control and 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 control kernels and those less contaminated in the AF13-inoculated group. It is expected that the results of this research could benefit the corn industry by mitigating the aflatoxin contamination problem in post-harvest management. Keywords: Aflatoxin, Aspergillus flavus, Compression rupture force, Corn, Fungus-infected, Inoculation, Mechanical strength.