脉冲强光对微生物的杀菌效果

1、脉冲强光对微生物的杀菌效果脉冲强光是一项有望取代传统的物理和化学杀菌手段的新技术，它是利用瞬 时的、高强度的脉冲光能量，有效杀灭暴露在食品和包装材料表面或水中的细菌、 霉菌、抱子、病毒、原生质、休眠抱子等各类微生物以及食品中的内源酶。脉冲 强光对各类微生物杀菌效果都非常明显，而且它是一种无汞、低热、无副产物的新 型杀菌技术。intensive pulse light sterilization effect of microbialPulse impact intensive pulse light is an expected to replace the traditional physi

2、cal and chemical sterilization method of new technology, it makes use of instantaneous pulse light energy of high strength, exposed to the food and packaging material surface or effectively kill the bacteria in the water mould spore protoplasm virus dormant spores and other kinds of microorganism an

3、d food of endogenous enzymes, intensive pulse light sterilization effects of all kinds of microorganisms are very obvious, and it is a kind of mercury-free low thermal no by-products of new sterilization technology一、脉冲强光杀菌机理.光化作用由于细菌的细胞中含有细菌的遗传信息核酸，当核酸被脉冲强光照射时会大量 吸收紫外光，从而在体内形成一部分的间二氮杂苯和间二氮杂苯的异构体。这种物

4、 质会使细菌自身的新陈代谢机能出现障碍，并且会导致细菌的遗传性出现问题，直 至死亡。脉冲强光中的200-280nm部分最易被吸收，光化作用主要是UVC.光热作用虽然光化作用主要来自于 UVC但脉冲强光的UV用口 UVBSB分也起着一定的杀 菌作用。当辐射剂量达到一定的水平，UVAffi UVEM以使细胞的表面温度迅速升高至130 C,从而破坏细菌的细胞壁，使细胞液蒸发，彻底破坏细胞结构，导致死 亡二、脉冲强光对大肠杆菌的杀菌实验.实验装置以及参数自制脉冲强光杀菌装置，该装置采用电容式脉冲发生电路，手动控制，使用 直管型脉冲强光灯做脉冲光源，用半圆柱形反光面对脉冲光源聚光。经测试，装置 所发出脉

5、冲强光波长范围为2001100nm，脉冲强光的脉冲宽度为20仙s,最大输入 能量为644J。该装置光照强度、闪照次数、闪照间隔、受照射物体离光源的距离 均可调节控制。.实验方法菌液的制备将斜面试管中的大肠杆菌活化，在无菌超净工作台中接种于无菌水中，接种量 控制在106107个/ml。处理方法每个直径为75 mm平皿盛入一定体积的待处理菌液，放在杀菌处理室中央，与 光源地距离2 cm,按照设定的工艺参数进行脉冲强光闪照处理，每次重复试验3 次。试验参数设置光照强度：0. 2, 0. 25, 0. 3, 0, 375,0. 5, 0, 625, 0. 75 J /cm2 ;闪照次数：1,2, 4,

6、 8, 16; 菌液厚度:3. 4, 6, 8, 10, 2, 13. 6, 17 cm;菌液透光率：1,2, 4, 8, 16, 32;菌液浓度（稀释彳数）:10, 100, 1 000 倍。大肠杆菌致死检验将处理完的菌液按1 ： 10稀释，选取10- 2 , 10- 3 , 10- 4,10 - 5 , 10 - 6,5个稀释度，每个稀释度做3次重复试验，记数时取平均值。菌检使用蛋白 陈培养基。经培养后与对照组（未经处理的同样菌种）进行比较。将处理过的菌用平板计数法进行活菌数的检测。杀菌率=（对照残菌数-处理残菌数）/对照残菌数X 100%选择光照强度、闪照次数、菌液厚度、菌液透光率、菌液

7、浓度作为影响因 素。.实验结果光照强度对杀菌效果的影响光照强度与杀菌率成正比，杀菌率随光照强度增加而增加，当光照强度为 0.75J/cm2时大肠杆菌完全至死。闪照次数对杀菌效果的影响在光照弓虽度为0.5J/cm2,菌液厚度3.4 mm,菌液透光率为100的情况下，采用 不同的闪照次数进行处理。闪照次数与杀菌率成正比，杀菌率随闪照次数增加而增 加。菌液厚度对杀菌效果的影响在透光率为1的情况下，菌液厚度与杀菌率成反比，菌液液层越厚，杀菌越 低。当透光率为100时，改变菌液厚度，杀菌率基本没有变化。由此得出，菌液厚度 与菌液透光率相互影响，一定菌液厚度只有在一定透光率下才影响杀菌效果 ，反之, 也成

8、从以上结果分析可看出，脉冲强光杀菌对于大肠杆菌的杀菌效果是十分显著 的，在几个脉冲就可达到完全致死，与传统紫外线杀菌相比，在相同的杀菌效果 下，杀菌处理时间更快，该技术是一种具有广阔前景的杀菌技术，对其他微生物杀 菌效果如下表：菌种处理方式杀灭效果来源大肠杆菌辐照强度0.5J/cm2闪照16次6个数量东北林业大学林学院沈阳农业大学食品学院枯草芽抱杆菌输入能量700J闪照30次5个数量级华南理工大学食品生物工程学院单核细胞增生李斯特菌单次输入3J闪照200次4个数量级苏格兰斯特拉斯克莱德大学生物科学 和生物技术学院沙门氏菌单次输入3J闪照200次4个数量级苏格兰斯特拉斯克莱德大学生物科学 和生物

9、技术学院金黄色球菌辐照强度5.6J/cm2 闪照5S8个数量 k美国宾夕法尼亚州立大学农业和生物工程学院酿酒酵母菌输入能量700J7个数量华南理工大学生物工程学院闪照30次级啤酒酵母菌单次输入7J闪照50次6-8个数量级比利时根特大学食品微生物学和食品化学实验室黑曲霉菌输入能量700J闪照40次4个数量级华南理工大学生物工程学院疱疹病毒HSV-11.0 J/cm2 的总剂量5个数量级英国赫特福特郡生物食品研究所牛疹病毒2.0 J/cm2 的总剂量4-8个数量级英国赫特福特郡生物食品研究所甲型肝炎病毒2.0 J/cm2 的总剂量5个数量 级英国赫特福特郡生物食品研究所Pulse strong l

10、ight sterilization effect of microbialPulsed light is a new technology which expected to replace the traditional physical and chemical sterilization method of, it makes use of instantaneous pulse light energy, high strength, effectively kill exposed to the food and packaging material surface or the

11、water of bacteria, mould and spores, and viruses, plasmids, dormant spores and other kinds of microbes, and endogenous enzymes in food. Pulse strong light sterilization effects of all kinds of microorganisms are very obvious, and it is a kind of mercury-free, low heat, no byproduct of new sterilizat

12、ion technology.A, pulse strong light sterilization mechanismphotochemical actionDue to bacteria bacterial genetic information is contained in the cell, when nucleic acid absorbed by pulse light when a large number of ultraviolet light, and thus formed in the body part between the two between nitroge

13、n impurity benzene and two nitrogen impurity benzene isomers. Appear this kind of material can make the bacterias own metabolism function disorder, and can lead to bacterial genetic problems, until they die. Pulses of light in the 200-280 - nm parts most likely to be absorbed, allochromatic mainly U

14、VC.The effect of fieldAlthough allochromatic mainly comes from the UVC, pulse strong light part of UVA and UVB rays also plays a certain sterilization effect. Reaches a certain level when doses of radiation, UVA and UVB rays can make cell surface temperatures soared to 1300 C, and destroy bacteriace

15、ll wall, make the cell SAP evaporation, thoroughly destroy the cellular structure, leading to death.Pulses of light pulse light treated beforeSecond, pulse strong light sterilization experiments of e. coliThe experimental apparatus and parameterSelf-made pulse strong light sterilization device, the

16、device adopts capacitive pulse generating circuit, manual control, using ZhiGuanXing pulse pulse light source, strong light do face pulse with halfcylindrical reflector lamp condenser. Tested, the device emits pulses of light wavelength range of 200 200 nm, the pulse width of pulse light for 20 mu s

17、, maximum input energy of 644 j. The devices light intensity, flash, flash pictures, irradiated between the distance of the object from the source is controlled can be adjusted.The methodbacteria liquid preparationWill cant tube from e. coli activation, in sterile ultra clean workbench vaccination i

18、n sterile water, quantity of control in 106 107 / cessing methodEach a diameter of 75 mm plate to a certain volume of pending bacteria liquid, placed in the middle of the sterilization chamber, and light source distance is 2 cm, according to the set of process parameters of pulse light flash a

19、ccording to processing, each test 3 times again.test parameter is setLight intensity: 0. 2, 0. 25, 0. 3, 0. 375, 0. 5, 0. 625, 0. 75 J/cm2;Flash according to number: 1,2, 4, 8, 16; Bacteria liquid thickness: 3,6, 8, 10. 2, 13. 6, 17 cm; Bacteria liquid light transmittance: 1, 2,8, 16, 32; Bacteria l

20、iquid concentration (diluted multiples) : 10, 100, 1 000 times.e. coli death inspectionW川 finish processing of diluted liquid press 1:10, 10-2, 10-3, 10-4, 5, 10-10-6, 5 dilution degrees, each dilution degrees do test 3 repetitions, the average number. Bacteria use peptone medium. After training wit

21、h the control (untreated strains of the same).W川 be treated bacteria by the plate count method detection of the number of living bacterium.Sterilization rate = (control residual bacterium number - processing and bacterium number)/control the residual count x 100%Select flash light intensity, accordi

22、ng to the number and thickness of the liquid, liquid light transmittance, bacteria liquid concentration as influencing factors.The experimental resultslight intensity of sterilization effectLight intensity is proportional to the sterilization rate, sterilization rate increased with the increase of l

23、ight intensity, when light intensity is 0.75 J/cm2 escherichia coli completely to death.number of times of flash as sterilization effectIn the light intensity is 0.5 J/cm2, bacterium liquid thickness is 3.4 mm, bacterium liquid light transmittance for 100 cases, adopt different flash as times for pr

24、ocessing. According to frequency is proportional to the sterilization rate, the sterilization rate increased with the increase of flash according to the number of times.liquid thickness of bactericidal effectIn the case of transmittance of 1, bacterium liquid thickness is inversely proportional to t

25、he sterilization rate, liquid liquid layer is thick, the lower the sterilization. When the light transmittance is 100, by changing the thickness of the microbial sterilization rate basic did not change. Thus, bacteria liquid thickness and the fungus liquid light transmittance influence each other, a

26、nd certain bacteria liquid thickness only under a certain light transmittance influence bactericidal effect, on the other hand, is established.Results from the above analysis we can see, pulse strong light sterilization for e. coli sterilization effect is very significant, in a few pulse can achieve

27、 full to death, compared with the traditional ultraviolet sterilization, under the same sterilizing effect, sterilization time faster, the technology is a kind of has a broad prospect of sterilization, sterilization effect of other microorganismsin the following table:Bacteria speciesMode,Kill out e

28、ffectTo the sourceE. coliIrradiation intensity of 0.5 J/cm2Flash according to 16 times6 orders of magnitudeForestry college of northeast forestry universityShenyang agricultural university college of foodBacillus subtilisThe input energy of 700 jFlash as 30 timesFive orders of magnitudeSouth China u

29、niversity of technology institute of food biotechnologyListeria monocytes hyperplasiaA single input 3 jFlash as 200 timesFour orders of magnitudeScotland at the university of strathclyde institute of biologicalsciences and biotechnologysalmonellaA single input 3 jFlash as 200 timesFour orders of magnitudeScotland at the university of strathclyde institute of biological sciences and biotechnolo