Analysis Of Spoilage Bacteria Of Fresh Wet Noodles And Screening Of Fresh-keeping Inhibitors

Fresh wet noodles have rich nutritional value,chewy texture,good cooking resistance,simple production process and easy to carry.Due to the high moisture content of the fresh wet noodles,the production,storage and transportation are susceptible to contamination by spoilage microorganisms,resulting in a short shelf life of the fresh wet noodles.Therefore,the development of new technologies for fresh-keeping wet noodles is of great significance.In the experiment,commercially available fresh wet noodles were used as experimental materials to separate,purify and identify spoilage bacteria from the fresh wet noodles.Taking six kinds of plant essential oils as the research object,the plant essential oils with excellent antibacterial effects were initially screened.Determine the minimum inhibitory concentration(Minimalinhibitcon centration,MIC)and(Minimum bactericidal concentration,MBC)and the combined antibacterial activity of the compound essential oil.Orthogonal test optimizes the compound essential oil formula.GC-MS was used to analyze the composition of clove essential oil,cinnamon essential oil and Litsea cubeba essential oil,and conduct stability tests to develop and optimize a fresh moist noodle preservation inhibitor formula.1.Three typical fungi S1,S2,S3 and three typical bacteria A1,A2,A3 were isolated from the fresh wet noodles by coating plate method.Morphological identification and molecular biology identification:S1 is Hyphopichia burtonii,S2 is Aspergillus flavus,S3 is Rhizopus oryzae;A1,A3,A5 are Staphylococcus gallinarum;A2 is Staphylococcus warneri;A4 is Bacillus safensis.2.Three kinds of plant essential oils,clove essential oil,cinnamon essential oil and litsea cubeba essential oil,which have strong bacteriostatic effect on six tested bacteria,were screened by filter paper method.3.Determine the minimum bactericidal concentration(MIC)value and the minimum inhibitory concentration(MBC)value of plant essential oil by solid double dilution method.The MIC values of clove essential oil,cinnamon essential oil and Litsea cubeba are 0.5-1?L/m Land 0.125?L/m L,respectively.1?L/m L and 0.125-1?L/m L,the MBC values of clove essential oil,cinnamon essential oil and Litsea cubeba are 0.5-1?L/m L,0.25?L/m L and 0.125-1?L/m L,respectively.4.The checkerboard dilution method was used to determine the combined antibacterial activity of clove essential oil,cinnamon essential oil and Litsea cubeba essential oil.Clove essential oil,cinnamon essential oil and Litsea cubeba essential oil had an effect on the six tested strains(Pichia burtonii,Aspergillus flavus,Rhizopus oryzae,Staphylococcus gallisepticum,Staphylococcus aureus and Bacillus saffron)are all additive.5.Staphylococcus aureus,Staphylococcus aureus and Bacillus Salmonii were used as test bacteria.The optimum ratio of clove essential oil,cinnamon essential oil and litsea cubeba essential oil was determined by filter paper method.As a result,the bacteriostatic effect was the best when the ratio of clove essential oil,cinnamon essential oil and litsea cubeba essential oil was 1:8:1,and the diameter of bacteriostatic zone reached 28.61±1.49 mm,36.95±0.06 mm and 27.47±0.17 mm,respectively.6.Orthogonal test optimizes the compound essential oil formula of clove essential oil,cinnamon essential oil and Litsea cubeba essential oil,confirms that the primary and secondary factors of compound essential oil on the tested bacteria are B>A>C,and confirms that the best compound combination of compound essential oil is A₁B₁C₁,namely Clove essential oil 2?L/m L,cinnamon essential oil concentration0.5?L/m L,Litsea cubeba essential oil 1?L/m L.7.The components of clove essential oil,cinnamon essential oil and Litsea cubeba essential oil were determined by gas chromatography-mass spectrometry.The main chemical components in clove essential oil are eugenol(89.16%),caryophyllene(3.77%),and clove acetate.Phenol ester(3.53%)and methyl eugenol(1.03%).The main chemical components in cinnamon essential oil are cinnamaldehyde(46.10%),?-pinene(6.03%),coumarin(5.33%),?-cadinene(3.80%)and?-yilanoleene(1.94).%).The main chemical components in Litsea cubeba essential oil are?-neral(46.10%),?-neral(30.73%),limonene(14.55%),dihydromyrcene(1.23%),eucalyptol(1.12%)and citronellal(1.04%).Clove essential oil,cinnamon essential oil and Litsea cubeba essential oil have good stability to temperature,ultraviolet radiation and other factors.