| The purpose of this research is to improve the shelf-life of mung bean sprouts.The aerobial plate count(APC),pH,TVB-N,and sensory evaluation are used as judgment index.The effect of different kinds of sanitizer on removing microorganisms and evaluating the preservation effect on sprouts was studied.After being isolated and purified from mung bean sprouts,the major microorganisms was identified by the method of 16S rRNA and being observed by Scanning Electronic Microscope(SEM)to find out the reason why microorganisms on mung bean sprouts were so difficult to be killed by common sanitizers.What's more,the possibility of inhibiting bacteria on mung bean sprouts by using Shermanni Propioncin was explored and the effect of different organic solvents on isolating and extracting propionicin was studied.The result shows:1.After being washed by sterile water,the mung bean seeds germinated.The APC in the sprouts were about 7.77 lg cfu/g.The APC of mung bean sprouts treated with 1000,2000 and 3000 mg/L NaClO solution was 7.08?5.46 and 5.00 lg cfu/g separately,while the sensory evaluation was decreased.15 and 25 mg/L Ag~+solution could cause APC decrease to 7.01 and 5.50 lg cfu/g.Further optimization experiments were conducted on the disinfection conditions of NaClO solution and Ag~+solution.2000 mg/L NaClO solution soaked at 40? for 10 min and 15 mg/L Ag~+solution soaked at 40? for 20 min showed the best results.The APC declined to 5.04 lg cfu/g and 6.26 lg cfu/g,respectively.The sensory score were both 87.The shelf-life was extended by 24h compared to the control group.2.Ten kinds of dominant bacteria were picked up from mung bean sprouts and isolated and purified many times.Those bacteria were all gram-negative after microscope observation.Using molecular biology methods,16S rRNA technology,to identify strains.These strains were Klebsiellosis,Escherichia,Acinetobacter,Pseudomonas,Enterobacter and Pseudacidovorax.3.The ability of removing microorganisms of NaClO solution and Ag~+solution in bacterial suspension with washing sprouts contained microorganisms was detected.The APC could be reduced to 3.00 lg cfu/mL and 4.30 lg cfu/mL,respectively,after the treatment of 3000 mg/L NaClO solution and 25 mg/L Ag~+solution.The result was significantly different when compared to washing sprouts which contained microorganisms.The observation of microorganisms on the surface of bean sprouts by SEM revealed that the microorganisms'colonies were accumulated and distributed on the surface of the sprout cells.The filaments could form a thick film-like substance which called biofilm.4.The produce process,extraction and application of a new kind of Shermanii propionicin were studied.The result shows best antibacterial activity when the volume ratio of fermentation broth to n-butanol was 1:1.5.The single factor trial of the cleaning condition was following:the sprouts were washed with 0.08%shermanii propionin at 35?,and the APC in the sprouts was decreased to 5.44 lg cfu/g.After being observed by SEM,the microorganisms was spread discretely and the biofilm on sprouts surface was destroyed and reduced.When storage in 4?,the pH and the TVB-N were change slowly.According to sensory evaluation,the shelf life of the sprouts was increased to 2 days.In addition,shermanii propioniocin has a certain antibacterial effect on Klebsiellosis,Acinetobacter and Pseudacidovorax which from sprouts,and some kinds of pathogens. |
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