Antibacterial mechanism of taxifolin and its application in milk preservation

Taxifolin is a flavonoid commonly found in fruits and vegetables with a variety of bioactivities. However, it is unknown whether taxifolin has positive effects on food preservation. In the present study, the antibacterial activity and mechanism of taxifolin on two foodborne bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), were investigated for the first time. Besides, its applications in milk preservation were evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of taxifolin on E. coli were 1.11 mg/mL and 2.22 mg/mL, while for S. aureus were 0.556 mg/mL and 1.11 mg/mL, respectively. Furthermore, taxifolin exhibited strong synergistic antibacterial activity with tetracycline. Taxifolin functions against the two strains of bacteria through damaging bacterial cell wall and membrane integrity, inhibiting bacterial biofilm formation, causing adversity and resulting in the increase of superoxide dismutase and alkaline phosphatase activities in bacteria. Moreover, morphological changes in bacteria were observed after exposure to taxifolin, including the formation of aggregates, irregular forms, wrinkled cell surfaces, and shriveling of cells. During milk storage, taxifolin significantly delayed the increase of acidity and the loss of lactose in milk through inhibiting the proliferation of bacteria. Hence, in addition to health-promoting bioactivities, taxifolin also has positive effects on food preservation because of antibacterial activity.