Abstract:

In order to elucidate the inhibitory mechanism of the essential oil from lotus leaves on Escherichia coli, Staphylococcus aureus and Salmonella commonly found in meat foods, the effect of the presence of the oil on the cell membrane permeability, electrical conductivity and reducing sugar and protein contents of the bacterial suspensions of these microorganisms was examined. All the bacterial suspensions presented higher electrical conductivity 5 min after addition of the oil, and their reducing sugar contents after addition of the oil decreased during the first two hours, followed by initial increase up to a climax at three hours and then decrease. During the first four hours of treatment with the oil, the soluble protein contents of the three bacterial suspensions decreased, and the subsequent change trend was initially increase up to a climax at eight hours, followed by decrease. In conclusion, the presence of the oil causes the change of cell membrane permeability and as a result, the leakage of cell contents happens to these three bacteria so that both conductivity and reducing sugar content increase. Moreover, the oil can delay protein synthesis in bacterial cells.

Key words: lotus oil, meat product, pathogenic bacteria, antibacterial mechanism, electrical conductivity