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[3La-01] Antibacterial Properties of Koji mold (Aspergillus oryzae) for Alternative Protein
Keywords:Aspergillus oryzae, Alternative protein, Antibacterial activity, Pasteurization
[Purpose] Koji (Aspergillus oryzae) has been emerging as a novel source of alternative protein. As the main ingredient in the alternative meat, it is important to study the storage characteristics of koji mycelium. This study aims to clarify the preservation of koji mycelium against the bacterial contamination for its development as an alternative protein. Specifically, the effect of heat treatment on the storage characteristics of koji mycelium was examined.
[Methods] Koji mycelium were cultivated in YG broth for 3 days and collected. The cultured koji mycelium was either pasteurized in the boiling water as a heat treatment or unpasteurized. Typical food-born bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), were inoculated to both pasteurized and unpasteurized koji samples at a concentration of 5 x 103 CFU/g. Cooked chicken breast was used as a control. Inoculated samples were stored at 20 ℃ for 0 to 4 days and the live bacterial cells was counted by the colony forming unit.
[Results] The unpasteurized koji showed a mere increase or even decrease in the bacterial growth for both E. coli and S. aureusstrains. In contrast, the pasteurized koji showed a dramatic increase as the storage period increased. It suggests that the koji mycelium contained antibacterial substances and it was vulnerable to the heat. Compared to the cooked chicken breast, the pasteurized koji showed a lower bacterial growth, indicating that even koji was heat-treated, it had a potential to inhibit the bacterial growth.
[Methods] Koji mycelium were cultivated in YG broth for 3 days and collected. The cultured koji mycelium was either pasteurized in the boiling water as a heat treatment or unpasteurized. Typical food-born bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), were inoculated to both pasteurized and unpasteurized koji samples at a concentration of 5 x 103 CFU/g. Cooked chicken breast was used as a control. Inoculated samples were stored at 20 ℃ for 0 to 4 days and the live bacterial cells was counted by the colony forming unit.
[Results] The unpasteurized koji showed a mere increase or even decrease in the bacterial growth for both E. coli and S. aureusstrains. In contrast, the pasteurized koji showed a dramatic increase as the storage period increased. It suggests that the koji mycelium contained antibacterial substances and it was vulnerable to the heat. Compared to the cooked chicken breast, the pasteurized koji showed a lower bacterial growth, indicating that even koji was heat-treated, it had a potential to inhibit the bacterial growth.