| During the process of storage and distribution, food is easy to be infected by a variety of microorganism which may result in food contamination. Most of traditional Chinese medicine has a bactericidal or bacteriostatic effect, but the antimicrobial spectrum of single herb is narrow. The compatibility of medicines can enhance the antibacterial activity and broaden the antimicrobial spectrum effectively, and has low toxicity, resistance and other advantages. According to historical records, Coptis chinensis,Scutellaria baicalensis and Forsythia suspensa have strong antimicrobial activity and less side effects, low price, with broad antimicrobial spectrum characteristics that can be used to further develop in the field of food preservation.This study analyzed the antimicrobial activity of ethanol extracts of single Coptis chinensis, Scutellaria baicalensis, Forsythia suspensa and their pairs, and filtered Coptis chinensis-Forsythia suspensa pair because of their good synergistic inhibitory effect. The vitro synergistic effect of Coptis chinensis-Forsythia suspensa pair was optimizated by mixture experimental design. The effects of Coptis chinensis and Forsythia suspensa on browning of fresh-cut lettuce, WI of fresh-cut carrot and other related indexes were studied.The conclusions are as follows:1.The inhibitory ability of Coptis chinensis, Scutellaria baicalensis, Forsythia suspensa and their pairs on seven tested Bacteria and Fungus was measured based on inhibition zone diameter and MIC which showed some inhibitory capacity; The in vitro synergistic effects of them were obtained by comparison with the theoretical value and the FIC index. Coptis chinensis-Scutellaria baicalensis and Scutellaria baicalensis-Forsythia suspensa pairs failed to show clear synergistic effect while Coptis chinensis-Forsythia suspensa pair showed a certain degree of synergistic or additive effects on the seven tested Bacteria and Fungus.2.To M.luteus, the formula of synergistic effect of Coptis chinensis-Forsythia suspensa pair was optimizated using Design Expert software, and the result showed the best ratio of Coptis chinensis and Forsythia suspensa is 4.523:5.477, and the FIC is 0.264375. The validation experiment with this ratio showed the FIC is 0.25,which is basically consistent with the prediction, so we can consider that the model has good applicability. 3.Chinese herb extracts were used to preserve fresh-cut lettuce under low temperature. Compared with the control groups, traditional Chinese medicine treatment inhibited the browning of fresh-cut lettuce, delayed the decline in Vc content, maintaining the original quality of fresh-cut lettuce, to extend the shelf life of more than 6d; traditional Chinese medicine treatment inhibited the increase of lignin content, thereby delayed the process of lignification of fresh-cut lettuce; In addition, Chinese medicine treatment also inhibited the reduction of cellulase activity, reduced the accumulation of cellulose content, inhibited the increase of pH, total number of colonies and the PPO, POD activity, but no significant effect on reducing weight loss. The ability of pair herbs dealing in the inhibition of increase in cellulose and lignin content, maintain Vc content, inhibition of increase in pH and the total number of colonies is stronger than single herbs.4.Chinese herb extracts were used to preserve fresh-cut carrot under low temperature. Compared with the control groups, traditional Chinese medicine treatment inhibited the WI of fresh-cut carrot, delayed the decline in Vc content, maintaining the original quality of fresh-cut carrot, to extend the shelf life of more than 10d; In addition, Chinese medicine treatment also inhibited the the increase of cellulose and lignin content, inhibited the increase of pH and PPO, POD activity, but no significant effect on reducing weight loss. The ability of pair herbs dealing in inhibition of increase in POD activity is stronger than single herbs.5.According to correlation analysis, during storage of fresh-cut lettuce, PPO activity and POD activity have certain influence on the browning index and the formation of lignin; during storage of fresh-cut carrot, POD activity has certain influence on the browning index and the formation of lignin, but PPO activity has no certain influence on them.In conclusion, this paper provides a data reference for the in vitro synergy antibacterial ability of Coptis chinensis-Forsythia suspensa and preservation technology of fresh-cut vegetables, and also provides a theoretical basis for the further development of traditional Chinese medicine compound preservative.
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