Inhibition Of Rabdosia Rubescens Extracts On Postharvest Fruit Rot Caused By Bacterium

In this paper, the optimum extracting conditions on its antimicrobial substances were studied by taking Jiyuan production of Rabdosia rubescens as raw material. The antibacterial experiments of Rabdosia rubescens extract on antibacterial activity of rot caused by common fruits were further investigated. The main research contents and conclusions are as follows:(1) Extraction technology of antibacterial components from Rabdosia rubescens were compared using ethanol refluxing extraction, ultrasonic assisted extraction, microwave extraction and microwave assisted extraction respectively, and in which ethanol refluxing extraction method is long and inefficiency. The time of microwave extraction and microwave assisted extraction is shorter, but their extraction rate is low, and microwave-assisted reflux extraction did not significantly increase the extraction rate. Compared with the three kinds of extraction method, the time of ultrasonic assisted extraction is shorter and Rabdosia rubescens extract weight relative to the highest. Ultimately,0.783g of Rabdosia rubescens extract was obtained from10g raw material.By single factor and orthogonal experiments, ultrasonic assisted ethanol reflux extraction technology of Rabdosia rubescens antibacterial substances were optimized, the best extraction conditions were: ultrasonic power is90W, extract ethanol concentration85%, ratio of material to liquid1:25and ultrasonic extraction time30min. The optimal extraction conditions, Rabdosia rubescens extract rate is the highest, the average yield reached89.22mg/g.(2) The antibacterial effect of extracts from Rabdosia rubescens was studied on Bacillus subtilis, Aspergillus niger, Penicillium, yeast, Bacillus anthracis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli by using filter paper method. It has ability to curb microorganisms that cause food spoilage by observation and comparison of inhibition zone diameter of Rabdosia rubescens extract to molds, yeasts and bacteria. It must be pointed out that the extract of Rabdosia rubescens exhibited strong antibacterial ability to5strains of bacteria, when the concentration of the extracts of Rabdosia rubescens reached10mg/mL, the inhibition rate against5strains of bacteria was above90%. And the extract of Rabdosia rubescens have good inhibitory effect on the germination of spores, when the concentration of the extracts of Rabdosia rubescens reached10mg/mL, the antibacterial rate was more than70%. the minimum inhibitory concentration (MIC) and minimum lethal concentration (MFC) of extract of Rabdosia rubescens were determined. The results show that the MIC of Pseudomonas aeruginosa was the smallest (3.13mg/mL), and the MIC of Aspergillus niger was the highest (25mg/mL). The MFC of Pseudomonas aeruginosa, Bacillus anthracis, Bacillus subtilis and yeast was reached12.5mg/mL, and the MFC of Penicillium and Aspergillus niger was reached25mg/mL and50mg/mL respectively. High concentrations of Rabdosia rubescens extract can not completely kill Staphylococcus aureus and Escherichia coli. It showed that the extract of Rabdosia rubescens has strong selectivity for inhibition of pathogens.(3) By acupuncture, in fruit inoculated extracts on the corresponding disease control effect observed at room temperature. The results show that, Rabdosia rubescens extract were able to infect different inhibition of Penicillium, Bacillus anthracis, Aspergillus niger and yeast for orange, apple, peach, fresh fruit in the larger than lethal concentration conditions, can effectively delay the onset of fruit and reduce the incidence of, and with the treatment concentration enhanced the inhibitory effect.