脉冲强光对微生物的杀菌效果

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、孢子、病毒、原生质、休眠孢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 physical 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 sporesand other kinds of microorganism and 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1.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。

2.光热作用虽然光化作用主要来自于UVC,但脉冲强光的UVA和UVB部分也起着一定的杀菌作用。

当辐射剂量达到一定的水平，UVA和UVB可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1.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，装置所发出脉冲强光波长范围为200~1100nm, 脉冲强光的脉冲宽度为20μs，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。

2.实验方法2.1 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106 ～107个/ml。

2.2 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。

2.3 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, 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(稀释倍数) : 10, 100, 1 000倍。

2.4 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。

菌检使用蛋白胨培养基。

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]×100%选择光照强度、闪照次数、菌液厚度、菌液透光率、菌液浓度作为影响因素。

3. 实验结果3.1 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。

3.2 闪照次数对杀菌效果的影响在光照强度为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。

3.3 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,也成立。

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：Pulse strong light 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 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 sterilization technology.A, pulse strong light sterilization mechanism1. photochemical 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 nitrogen impurity benzene and two nitrogen impurity benzene isomers. Appear this kind of material can make the bacteria's 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 UVC.2. The effect of fieldAlthough allochromatic mainly comes from the UVC, pulse strong lightpart 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 130 ° C, and destroy bacteria cell wall, make the cell SAP evaporation, thoroughly destroy thecellular structure, leading to death.Pulses of light pulse light treated beforeSecond, pulse strong light sterilization experiments of e. coli1. The experimental apparatus and parameterSelf-made pulse strong light sterilization device, the 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 lightfor 20 mu s, maximum input energy of 644 j. The device's light intensity, flash, flash pictures, irradiated between the distance of the objectfrom the source is controlled can be adjusted.2. The method2.1 bacteria liquid preparationWill cant tube from e. coli activation, in sterile ultra clean workbench vaccination in sterile water, quantity of control in 106 ~ 107 / ml.2.2 processing 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 according to processing, each test 3 times again.2.3 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, 4, 6, 8, 10. 2, 13. 6, 17 cm; Bacteria liquid light transmittance: 1, 2, 4, 8, 16, 32; Bacteria liquid concentration (diluted multiples) : 10, 100, 1 000 times.2.4 e. coli death inspectionWill 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 with the control (untreated strains of the same).Will be treated bacteria by the plate count method detection of the number of living bacterium.Sterilization rate = [(control residual bacterium number - processingand bacterium number)/control the residual count] x 100%Select flash light intensity, according to the number and thickness of the liquid, liquid light transmittance, bacteria liquid concentration as influencing factors.3. The experimental results3.1 light intensity of sterilization effectLight intensity is proportional to the sterilization rate, sterilization rate increased with the increase of light intensity, when lightintensity is 0.75 J/cm2 escherichia coli completely to death.3.2 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 processing. According to frequency is proportional to the sterilization rate, the sterilization rate increased with the increase of flash according to the number of times.3.3 liquid thickness of bactericidal effectIn the case of transmittance of 1, bacterium liquid thickness is inversely proportional to the 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, and certain bacteria liquid thickness only under a certain light transmittance influencebactericidal 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 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 effectTo the sourceE. coliIrradiation intensity of 0.5 J/cm2Flash according to 16 times6 orders of magnitudeForestry college of northeast forestry university Shenyang agricultural university college of foodBacillus subtilisThe input energy of 700 jFlash as 30 timesFive orders of magnitudeSouth China university 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 biological sciences and biotechnologysalmonellaA single input 3 jFlash as 200 timesFour orders of magnitudeScotland at the university of strathclyde institute of biological sciences and biotechnologyS. aureusIrradiation intensity of 5.6 J/cm2Flash according to 5 sEight orders of magnitudePennsylvania state university college of agricultural and biological engineeringBrewers yeastThe input energy of 700 jFlash as 30 timesSeven orders of magnitudeSouth China university of technology institute of biological engineeringBeer yeastA single input 7 jFlash as 50 times6-8 orders of magnitudeUniversity of Ghent in Belgium and food microbiology and food chemistry labaspergillusThe input energy of 700 jFlash as 40 timesFour orders of magnitudeSouth China university of technology institute of biological engineeringHerpes virus HSV - 1Total dose of 1.0 J/cm2Five orders of magnitudeThe hutt ford county biological food research instituteBovine herpes virusTotal dose of 2.0 J/cm24-8 orders of magnitudeThe hutt ford county biological food research institute Hepatitis a virusTotal dose of 2.0 J/cm2Five orders of magnitudeThe hutt ford county biological food research institute。