Inhibitory mechanism of Chinese herbal medicine extracts on Escherichia coli and its application to fermented-bag sausage

Since Chinese Herbal Medicine contain many antimicrobial chemicals, they have great potential as new anti-microbial agents. Five Chinese Herbal Medicine extracts were obtained from hawthorn leaf, ginkgo leaf, bamboo leaf, redskin peanut, and lotus leaf by thermal reflux. The optimal mixed ratio was 2: 2: 5: 9 (hawthorn leaf, ginkgo leaf, bamboo leaf, redskin peanut) using the orthogonal method. The minimum inhibitory concentration (MIC) was 1.3 mg/mL. The total flavonoid content in the mixed-plant extract was 21.5%, and the quercetin, vitexin, different vitexin, galangal and resveratrol content were 0.32, 4.38, 1.87, 0.36 and 1.35 mg/L, respectively. The inhibitory mechanism was studied by changes in growth curves, cellular structure, cell-wall permeability and cell-membrane integrity. Results showed that the addition of plant extracts reduced the presence of E. coli, while increasing AKP, conductivity and ion-channel enzymes. Plant extracts damaged E. coli cell-walls and cell-membrane structures. The addition of 6% mixed-plant extract showed a positive effect on the quality and safety of fermented-bag sausage.