Research On Ultrasonic-assisted Extraction Technology Of Shallot Oil And Its Antibacterial Effects

This paper aims to extract shallot oil from shallot, and analysis the active constituent, observe the result of which restrain the microbe at the same time, hope to have a breakthrough on the extraction of shallot oil and improve the value of it, meanwhile it also have a great sense on the development and exploit of the native spice and native additive in the field of food.In this paper, first, to study on the enzymolysis temperature and enzymolysis time of shallot in preprocessing stage.By single factor tests,the optimum temperature was 35℃,time was 60minutes,in these conditions,the yield of shallot oil will get the best value.Then, ultrasound wave assisted extract shallot oil taking organic solvent as supporter, which contains light petroleum, ethyl acetate, dichloromethane, trichloromethane, ether, normal hexane, with the condition of material:dissolvent 1:4, ascertain the best dissolvent is dichloromethane. Take the shallot oil yield as indicator and dichloromethane as the only supporter, the optimum ratio of solid to solution was found as 1:3, which based on the single factor test of ratio of solid to solution respectively 1:2,1:3,1:4,1:5. Then test and analysis the influence of different parameter of ultrasound wave to yield of shallot oil, power of ultrasound wave as follows:100W,150W, 200W,250W,300W, time of ultrasound wave:20minutes,30minutes,40minutes,50minutes,60minutes, temperature of ultrasound wave:25℃,30℃,35℃,40℃,45℃, the optimum confine was found respectively, and optimize the element with the experiment of response surface, the optimum indexs were as follows:power of ultrasound wave was 209W, time of ultrasound wave was 37minutes, temperature of ultrasound wave was 31℃, the yield of shallot oil was 4.45g/kg which reach the maximum. The liquid was stabilize and brown. The yield of shallot oil was improved remarkably with the use of ultrasound wave. contrast with other technology, this technology was good with some merits such as a small quality of solvent, high extraction yield, low temperature, low power and so on.On the experiment of bacteriostasis, take putrefying bacteria and pathogenic bacteria for experiment such as Staphylococcus aureus, Salmonella, Aspergillus niger, Saccharomyces cerevisiae ect which ten in total. Analysis the bacteriostasis qualitatively by the method of inhibition zone to find the extraction has a inhibition effection to the microbe which containd above, for the Aspergillus niger, Saccharomyces cerevisiae, Issatchenkia terricola, colibacillus, Shigella, the effection is significant, while for the penicillium, Aspergillus flavus, the effection is non significant.Ascertain the lowest inhibition concentration through the method of cultivating the bacterium on the culture medium which contains different quantity of extraction, measure the amount of the bacterium in the culture medium to found the lowest inhibition concentration, when the extraction concentration above 0.3125%, most of the bacterium will be inhibited, when the concentration reach 0.625%, the other bacterium will be inhibited too. All of the above, the shallot oil has a comprehensive inhibition effection to bacterium.