Research On The Key Technology Of Safety Control And Preservation Of Pathogens In Ready-to-eat Noodles

In the process of packaging and storage,ready-to-eat noodles was susceptible to microbial secondary contamination,which seriously affected edible safety.The objects of this research were Salmonella,Listeria monocytogenes and Staphylococcus aureus,which are the commonly detected foodborne pathogens.Bactericidal and bacteriostatic effects of PL(25 ℃)and CMG(25 ℃and 4 ℃)of the three kinds of pathogenic bacteria were studied and in order to find a new method for the preservation of ready-to-eat noodles,the bacteriostatic model of Staphylococcus aureus was established under different temperature and different concentration.The final experiment using pulsed light,bacteriostatic agent,low temperature and deoxidation packaging of this hurdle technology on preservation of ready-to-eat noodles was evaluated by analyzing changes in the bacteria numbers,whiteness,p H value and sensory evaluation of ready-to-eat noodles.The experimental results on three kinds of bacteria by pulsed light sterilization are as follows:(1)The experimental results of physiological saline showed that the effect of pulsed light increased with the increasing of the single pulse energy and the number of flashes,and decreased with the increase of the pulse distance.When the pulse distance was 9cm,the single pulse energy was 500 J,the flash times were 9,20,and16 times respectively,the sterilization effect of pulsed light sterilization equipment on the three kinds of bacteria was stable.(2)Pulsed light on(packaged and unpackaged ready-to-eat noodles)were flashed and the experimental results show that: the pulse light sterilization equipment can effectively reduced the bacteria numbers on both aseptic packaged and unpackaged ready-to-eat noodles,and when the flash was 20,30 and 25 times,the killed number three kinds of bacteria reached 2.37 log CFU/g、2.06 log CFU/g and 2.32 log CFU/g,respectively;and the packaged and unpackaged ready-to-eat noodles to reduce the number of pathogens had no significant difference(P > 0.05),which indicated that the packaging material has no obvious effect on the sterilization effect of pulsed light.(3)The results of transmission electron microscopy showed that there was alarge hole in the middle of cell,and the contour was fuzzy,and some of the walls were absent,the internal structure of the cell was disordered and the contents of the three kinds of pathogens were exposed.It can be concluded that the mechanism of pulse light is similar to that of three kinds of bacteria,which is through destructing the cell wall and the internal structure to kill bacteria.The antibacterial mechanism under the conditions of CMG(25 ℃ and 4 ℃,respectively)on three kinds of pathogenic bacteria through the changes in morphological and biochemical indexes was also discussed.The results of this research were as follows:(1)The inhibitory effects of CMG at 25 ℃and 4 ℃on three kinds of food borne pathogenic bacteria have discussed: 25 ℃CMG can inhibit the growth of bacteria and three species,0.1% CMG had the best antibacterial effect;low temperature and CMG showed a synergistic inhibitory effect to three strains.CMG can inhibit the pathogenic bacteria in ready-to-eat noodles,but in order to achieve the best preservation effect,it is necessary to combine with other means of preservation.(2)Transmission electron microscopy was used to observe the changes of the three pathogenic bacteria before and after treatment with CMG.The results showed that after CMG treatment,the Salmonella appearance becomes blurred,some cell wall membrane deletion;Listeria monocytogenes bacteria Lester dull and dull,lack of cell wall and membrane;Staphylococcus aureus cell wall and membrane damage of individual cells broken,contents overflow.It can be concluded that the inhibition of CMG on three kinds of pathogenic bacteria by destroying the cell wall.Ready-to-eat noodles was aseptic packaged,adding CMG,pulsed light treatment,packaging and preservation under 4 ℃.The experimental results showed that the technology can significantly inhibit the bacteria numbers,p H value and sensory evaluation,thereby prolonging the shelf life of ready-to-eat noodles.