脈沖強光對微生物的殺菌效果

1、脈沖強光對微生物的殺菌效果脈沖強光是一項有望取代傳統(tǒng)的物理和化學(xué)殺菌手段的新技術(shù)，它是利用瞬 時的、高強度的脈沖光能量，有效殺滅暴露在食品和包裝材料表面或水中的細(xì)菌、 霉菌、抱子、病毒、原生質(zhì)、休眠抱子等各類微生物以及食品中的內(nèi)源酶。脈沖 強光對各類微生物殺菌效果都非常明顯，而且它是一種無汞、低熱、無副產(chǎn)物的新 型殺菌技術(shù)。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、脈沖強光殺菌機理.光化作用由于細(xì)菌的細(xì)胞中含有細(xì)菌的遺傳信息核酸，當(dāng)核酸被脈沖強光照射時會大量 吸收紫外光，從而在體內(nèi)形成一部分的間二氮雜苯和間二氮雜苯的異構(gòu)體。這種物

4、 質(zhì)會使細(xì)菌自身的新陳代謝機能出現(xiàn)障礙，并且會導(dǎo)致細(xì)菌的遺傳性出現(xiàn)問題，直 至死亡。脈沖強光中的200-280nm部分最易被吸收，光化作用主要是UVC.光熱作用雖然光化作用主要來自于 UVC但脈沖強光的UV用口 UVBSB分也起著一定的殺 菌作用。當(dāng)輻射劑量達(dá)到一定的水平，UVAffi UVEM以使細(xì)胞的表面溫度迅速升高至130 C,從而破壞細(xì)菌的細(xì)胞壁，使細(xì)胞液蒸發(fā)，徹底破壞細(xì)胞結(jié)構(gòu)，導(dǎo)致死 亡二、脈沖強光對大腸桿菌的殺菌實驗.實驗裝置以及參數(shù)自制脈沖強光殺菌裝置，該裝置采用電容式脈沖發(fā)生電路，手動控制，使用 直管型脈沖強光燈做脈沖光源，用半圓柱形反光面對脈沖光源聚光。經(jīng)測試，裝置 所發(fā)出脈

5、沖強光波長范圍為2001100nm，脈沖強光的脈沖寬度為20仙s,最大輸入 能量為644J。該裝置光照強度、閃照次數(shù)、閃照間隔、受照射物體離光源的距離 均可調(diào)節(jié)控制。.實驗方法菌液的制備將斜面試管中的大腸桿菌活化，在無菌超凈工作臺中接種于無菌水中，接種量 控制在106107個/ml。處理方法每個直徑為75 mm平皿盛入一定體積的待處理菌液，放在殺菌處理室中央，與 光源地距離2 cm,按照設(shè)定的工藝參數(shù)進行脈沖強光閃照處理，每次重復(fù)試驗3 次。試驗參數(shù)設(shè)置光照強度：0. 2, 0. 25, 0. 3, 0, 375,0. 5, 0, 625, 0. 75 J /cm2 ;閃照次數(shù)：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;菌液濃度（稀釋彳數(shù)）:10, 100, 1 000 倍。大腸桿菌致死檢驗將處理完的菌液按1 ： 10稀釋，選取10- 2 , 10- 3 , 10- 4,10 - 5 , 10 - 6,5個稀釋度，每個稀釋度做3次重復(fù)試驗，記數(shù)時取平均值。菌檢使用蛋白 陳培養(yǎng)基。經(jīng)培養(yǎng)后與對照組（未經(jīng)處理的同樣菌種）進行比較。將處理過的菌用平板計數(shù)法進行活菌數(shù)的檢測。殺菌率=（對照殘菌數(shù)-處理殘菌數(shù)）/對照殘菌數(shù)X 100%選擇光照強度、閃照次數(shù)、菌液厚度、菌液透光率、菌液

7、濃度作為影響因 素。.實驗結(jié)果光照強度對殺菌效果的影響光照強度與殺菌率成正比，殺菌率隨光照強度增加而增加，當(dāng)光照強度為 0.75J/cm2時大腸桿菌完全至死。閃照次數(shù)對殺菌效果的影響在光照弓雖度為0.5J/cm2,菌液厚度3.4 mm,菌液透光率為100的情況下，采用 不同的閃照次數(shù)進行處理。閃照次數(shù)與殺菌率成正比，殺菌率隨閃照次數(shù)增加而增 加。菌液厚度對殺菌效果的影響在透光率為1的情況下，菌液厚度與殺菌率成反比，菌液液層越厚，殺菌越 低。當(dāng)透光率為100時，改變菌液厚度，殺菌率基本沒有變化。由此得出，菌液厚度 與菌液透光率相互影響，一定菌液厚度只有在一定透光率下才影響殺菌效果 ，反之, 也成

8、從以上結(jié)果分析可看出，脈沖強光殺菌對于大腸桿菌的殺菌效果是十分顯著 的，在幾個脈沖就可達(dá)到完全致死，與傳統(tǒng)紫外線殺菌相比，在相同的殺菌效果 下，殺菌處理時間更快，該技術(shù)是一種具有廣闊前景的殺菌技術(shù)，對其他微生物殺 菌效果如下表：菌種處理方式殺滅效果來源大腸桿菌輻照強度0.5J/cm2閃照16次6個數(shù)量東北林業(yè)大學(xué)林學(xué)院沈陽農(nóng)業(yè)大學(xué)食品學(xué)院枯草芽抱桿菌輸入能量700J閃照30次5個數(shù)量級華南理工大學(xué)食品生物工程學(xué)院單核細(xì)胞增生李斯特菌單次輸入3J閃照200次4個數(shù)量級蘇格蘭斯特拉斯克萊德大學(xué)生物科學(xué) 和生物技術(shù)學(xué)院沙門氏菌單次輸入3J閃照200次4個數(shù)量級蘇格蘭斯特拉斯克萊德大學(xué)生物科學(xué) 和生物

9、技術(shù)學(xué)院金黃色球菌輻照強度5.6J/cm2 閃照5S8個數(shù)量 k美國賓夕法尼亞州立大學(xué)農(nóng)業(yè)和生物工程學(xué)院釀酒酵母菌輸入能量700J7個數(shù)量華南理工大學(xué)生物工程學(xué)院閃照30次級啤酒酵母菌單次輸入7J閃照50次6-8個數(shù)量級比利時根特大學(xué)食品微生物學(xué)和食品化學(xué)實驗室黑曲霉菌輸入能量700J閃照40次4個數(shù)量級華南理工大學(xué)生物工程學(xué)院皰疹病毒HSV-11.0 J/cm2 的總劑量5個數(shù)量級英國赫特福特郡生物食品研究所牛疹病毒2.0 J/cm2 的總劑量4-8個數(shù)量級英國赫特福特郡生物食品研究所甲型肝炎病毒2.0 J/cm2 的總劑量5個數(shù)量 級英國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