Antibacterial activity of Chinese herbal medicines and their preservation effects on cherry tomato

【Objective】To study the antibacterial activities of Rhus chinensis Mill.，olive leaf，Reynoutria japonica Houtt.，Taraxacum mongolicum and their preservation effects on cherry tomato，which could provide reference for the development of green and safe preservative for cherry tomato and the research of natural food preservation.【Method】The extracts of R. chinensis，olive leaf，R. japonica and T. mongolicum were produced by ethanol，Escherichia coli，Staphylococcus aureus，Bacillus subtilis，Saccharomyces cerevisiae and Aspergillus niger were used as indicator bacteria，the antibacterial effect of extracts of R. chinensis，olive leaf，R. japonica and T. mongolicum were determined by oxford cup method，the minimum inhibitory concentration（MIC）were determined by double dilution method.The extracts of R. chinensis and olive leaf with different concentrations（50.00 and 100.00 mg/mL）were sprayed on the surface of cherry tomato，distilled water was used as blank control（CK），the preservation of cherry tomato was investigated by measuring sensory evaluation，decay rate，weight loss rate，hardness，titratable acid，soluble solid and vitamin C（Vc）.【Result】The four Chinese herbal medicines all had different degrees of antibacterial effect on E. coli，S. aureus，B. subtilis，S. cerevisiae and A. niger，R. chinensis and olive leaf had the best bacteriostatic effect，the antibacterial zone diameters were 18.47 and 20.00 mm，17.77 and 22.00 mm，15.90 and 17.00 mm，14.83 and 13.00 mm，15.93 and 14.07 mm respectively；MIC were 62.50 and 15.63 mg/mL，31.25 and 7.81 mg/mL，31.25 and 15.63 mg/mL，62.50 and 31.25 mg/mL，62.50 and 62.50 mg/ mL respectively. It could be seen from the results of preservation test results of cherry tomato that，compared with CK， 50.00 and 100.00 mg/mL of R. chinensis and olive leaf extracts could improved the preservation effect of cherry tomato to varying degrees. Storage until 10 d，compared to other processing groups，100.00 mg/mL olive leaf extract treatment group had the best preservation effect on sensory score（46.15），the decay rate（16.67%），weight loss rate（4.50%），hardness （1.20 kg/cm²），Soluble solid content （6.18%）and Vc content （31.50 mg/100 g），the difference with CK was significant （P< 0.05）or extremely significant（P<0.01，the same below）. The content of titratable acid（0.48%）was the highest in 100.00 mg/mL R. chinensis extract group，the difference between CK was extremely significant.【Conclusion】The olive leaf extract of 100.00 mg/mL has the best preservation effect on cherry tomato，and has a good application prospect as a natural preservative.