用ORP监控鲜切果蔬臭氧水消毒的实验研究

研究了用氧化还原电位(ORP)监控臭氧水对鲜切果蔬的消毒灭菌过程,通过不同ORP的臭氧水消毒实验发现,将鲜切果蔬浸入ORP超过800mV的臭氧水中超过30s可以使细菌总数下降约2个数量级。通过改变臭氧浓度和水温的方法研究了臭氧水ORP的影响因素,得出了提高臭氧气体浓度和低温制冷有利于制取高ORP臭氧水的结论。结果表明,利用ORP监测臭氧水的消毒能力是可行的。     

黄瓜在纯菌接种恒温发酵过程中的化学成分变化

以来自于自然发酵蔬菜的三种乳酸茵为黄瓜发酵菌种,通过控制发酵过程的条件,探讨其理化性质变化及微生物变化规律.结果表明,黄瓜在纯茵接种恒温(38℃)发酵过程中,其pH逐渐降低,总酸度增高,黄瓜中总糖的含量随发酵时间延长而减少,在发酵约70.5h后趋于稳定而达到发酵终点.该发酵过程黄瓜中亚硝酸盐含量少,亚硝峰出现较快(约70.5h左右),118.5h后已经下降到很低;在发酵过程中杂茵的生长繁殖被抑制,发酵后期大肠茵群数降到很低;发酵黄瓜中Vc损失小于30%.     

苦瓜水提物抑菌作用的初步探讨

测定分析了苦瓜水提物时十种常见食品污染微生物的抑茵活性.结果表明,苦瓜水提物时金黄色葡萄球菌、沙门氏茵、大肠杆茵、枯草杆菌等受试细菌具有良好的抑制作用,尤其对金黄色葡萄球菌、沙门氏茵等致病茵的抑制效果显著;苦瓜水提物对受试霉茵米曲霉、黑曲霉、桔青霉以及受试酵母啤酒酵母、粘红酵母、假丝酵母的抑制作用较弱.     

氧化还原电位的研究进展及相关应用

近年来,在线监测已成为污废水处理精细化控制领域的重要研究内容和发展方向。氧化还原电位作为过程的综合性监测指标,以达到控制所需能源以及降低经济成本的目的。根据能斯特方程以及电化学反应动力学,化学反应的本质过程是一个氧化还原反应过程,而ORP的变化可以从ORP值上反映出来。且ORP作为其他很多反应过程中的监测指标的技术已经发展的比较成熟。文章综述氧化还原电位的基本概念、测量原理、影响因素以及其应用的国内外研究进展。     

纳米银与纳米氧化锌纺织材料抗菌作用的研究

观察不同浓度纳米银、纳米氧化锌纺织材料体外抗金黄色葡萄球菌和大肠埃希茵的作用.采用细菌生长抑制的定性和定量试验,测定含不同浓度的纳米银、纳米氧化锌纺织材料对金黄色葡萄球菌ATCC25923和大肠埃希菌ATCC25922的抑菌圈直径及抑菌率.结果含0.5%、0.7%、1.0%的纳米银和纳米氧化锌纺织材料对金黄色葡萄球菌ATCC25923的抑菌率则分别为95.13%、95.13%、97.57%和95.13%、90.27%、92.70%;相同浓度的纳米银和纳米氧化锌纺织材料对大肠埃希茵ATCC25922的抑菌率则为73.57%、62.97%、78.83%和78.83%、57.70%、100.00%.由此可见,低含量的纳米银、纳米氧化锌纺织材料对金黄色葡萄球菌和大肠埃希菌具有抗菌作用,且对金黄色葡萄球菌的抗菌作用更为显著.     

高品质蜜饯产品生产的关键技术研究及应用

传统工艺生产的果脯蜜饯产品,常存在糖分过高,超量使用食品添加剂、微生物超标和杂质多、口感差等质量问题.应用臭氧减茵、真空连续渗糖和密封式玻璃房晒干结合微波干燥工艺等集成新技术,可生产出高品质蜜饯产品.     

黑曲霉菌丝体真空冷冻干燥的研究

本文研究了黑曲霉(ATCC16404)茵丝体真空冷冻干燥的保藏方法,并从培养基和保护剂对冻干茵的影响进行了研究,初步确定了高活茵教的增殖培养基.比较了不同保护剂对茵丝体成活率的影响,确定了最佳保护剂,活菌数达到109cfu/g.     

ORP对微氧颗粒污泥降解五氯酚的影响

微氧颗粒污泥工艺能够同时进行好氧氧化和厌氧还原过程,是处理五氯酚(PEP)的理想方法.本研究对微氧颗粒污泥降解PCP限制性生态因子ORP(oxidation-reduction potential)的作用规律进行了研究.实验结果表明,PCP去除率随ORP的升高而降低,出水PCP、TeCP(四氯酚)和TCP(三氯酚)浓度随ORP的降低而降低,DCP(二氯酚)浓度却呈现升高的趋势.低ORP值下引起Cl-生成量降低,造成DCP的积累.随ORP的变化,CODCr去除率和产气量变化幅度很小.     

臭氧灭菌机理及消毒副产物溴酸盐控制技术研究进展

臭氧消毒作为氯消毒的替代方法,在饮用水处理中被越来越多地应用.臭氧灭菌作用是通过生物化学氧化反应实现的,灭菌性能试验表明,臭氧几乎对所有细菌、病毒、真菌及原虫、卵囊都具有明显的灭活效果.但是含有溴离子的水臭氧化过程中形成的消毒副产物溴酸盐,被国际癌症研究机构定为2B级潜在致癌物.臭氧氧化过程中溴酸盐的生成有臭氧氧化和臭氧/氢氧自由基氧化两种途径,控制溴酸盐可以从控制其形成和生成后去除两个方面进行.降低pH、添加氨气、氯-氨工艺和优化臭氧化条件是控制溴酸盐形成的方法,溴酸盐生成后则可以利用物理、化学和生物方法去除.因此要实现臭氧、致病菌与溴酸盐三者的平衡需进一步探讨臭氧灭菌机理及溴酸盐控制方法.     

降胆固醇乳酸菌WB的微胶囊化研究

研究了降胆固醇乳酸茵wB的微胶囊化工艺,并对微胶囊化后的产品进行了评价.以海藻酸钠、明胶为壁材.含有降胆固醇乳酸茵wB的硅藻土为芯材,采用W/O/W复相乳化法制备微胶囊.通过单因素和正交试验确定最佳制备工艺条件为:乳酸茵WB菌悬液质量分数为20%,内层水相中海藻酸钠和明胶的质量分数分别为2%和3%,外层水相中明胶质量分数为12%.以该工艺制备的乳酸茵WB微胶囊具有较好的耐酸性和肠溶性,产率在86.62%左右,10℃下储存30d,产品中活茵教仍可达到108mL-1,体外胆固醇降解率可达到36.07%.     

Roles of oxidation-reduction potential in electrolyzed oxidizing and chemically modified water for the inactivation of food-related pathogens

This study investigates the properties of electrolyzed oxidizing (EO) water for the inactivation of pathogen and to evaluate the chemically modified solutions possessing properties similar to EO water in killing Escherichia coli O157:H7. A five-strain cocktail (10(10) CFU/ml) of E. coli O157:H7 was subjected to deionized water (control), EO water with 10 mg/liter residual chlorine (J.A.W-EO water), EO water with 56 mg/liter residual chlorine (ROX-EO water), and chemically modified solutions. Inactivation (8.88 log10 CFU/ml reduction) of E. coli O157:H7 occurred within 30 s after application of EO water and chemically modified solutions containing chlorine and 1% bromine. Iron was added to EO or chemically modified solutions to reduce oxidation-reduction potential (ORP) readings and neutralizing buffer was added to neutralize chlorine. J.A.W-EO water with 100 mg/liter iron, acetic acid solution, and chemically modified solutions containing neutralizing buffer or 100 mg/liter iron were ineffective in reducing the bacteria population. ROX-EO water with 100 mg/liter iron was the only solution still effective in inactivation of E. coli O157:H7 and having high ORP readings regardless of residual chlorine. These results suggest that it is possible to simulate EO water by chemically modifying deionized water and ORP of the solution may be the primary factor affecting microbial inactivation.     

Effects of water source, dilution, storage, and bacterial and fecal loads on the efficacy of electrolyzed oxidizing water for the control of Escherichia coli O157:H7

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 10(4) CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to < 700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 10(4) CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24 degrees C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to < or = 848 mV. When stored in the dark, the diluted EO waters retained an ORP of > 848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4 degrees C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.     

Ozone treatment for reduction of Escherichia coli 0157:H7 and Salmonella serotype typhimurium on beef carcass surfaces

The effectiveness of an aqueous ozone treatment in reducing Escherichia coli O157:H7 and Salmonella serotype Typhimurium on hot carcass surfaces was determined with the use of a model carcass spray cabinet. Carcass surface regions were removed from carcasses and inoculated with feces containing 10(6) to 10(7) CFU each of E. coli O157:H7 and Salmonella Typhimurium per g and were then exposed to a water wash or to a water wash followed by a sanitizing ozone treatment. Water washes were applied at 28 degrees C beginning at a pressure of 10 lb/in2 and gradually increasing to 400 lb/in2. Ozone treatment was carried out by spraying surfaces with an aqueous ozone solution (80 lb/in2 at 28 degrees C) containing 95 mg of ozone per liter. Pathogen reductions achieved with ozone treatment were not significantly different from those achieved with a water wash alone. In addition, ozone treatment did not reduce E. coli O157:H7 or Salmonella Typhimurium contamination that was spread over the carcass surface as a result of the water wash. Under the conditions of this study, the aqueous ozone treatment applied resulted in no significant improvement over a water wash in reducing pathogens on beef carcass surfaces.     

Efficacy of electrolyzed oxidizing (EO) and chemically modified water on different types of foodborne pathogens

This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.     

Efficacy of aqueous ozone for the decontamination of Escherichia coli O157:H7 and Salmonella on raspberries and strawberries

The efficacy of ozone as a water additive for washing raspberries and strawberries was investigated. Pathogen-inoculated fruits were treated with aqueous ozone concentrations of 1.7 to 8.9 mg/liter at 20 degrees C for 2 to 64 min, with an aqueous ozone concentration of 21 mg/liter at 4 degrees C for 64 min, or with water as a control. Maximum pathogen reductions on raspberries were 5.6 and 4.5 log CFU/g for Escherichia coli O157:H7 and Salmonella, respectively, at 4 degrees C, whereas reductions on strawberries were 2.9 and 3.3 log CFU/g for E. coli O157:H7 and Salmonella, respectively, at 20 degrees C after 64 min. Washing with water (sparging with air as control) resulted in reductions of approximately 1 log CFU/g. The results presented here indicate that aqueous ozone may be useful as a decontaminant for small fruits.     

采用臭氧系统净化太平洋牡蛎中的大肠杆菌

采用人工方法使太平洋牡蛎(Crassostrea gigas)体内积累的埃希氏大肠杆菌(E.coli)达到5个对数值后,放入小型臭氧净化实验系统中,通过正交试验,研究了各种环境因子对太平洋牡蛎自身净化能力的影响。经48 h净化处理后,贝肉中的E.coli减小约2～3个对数值,太平洋牡蛎的最佳净化条件为:温度15℃、换水率3次/h、贝水质量比为1:4。海水中O_3浓度为0.1～0.2mg/L时具有明显的杀菌作用。同时分析了臭氧系统处理海水的原理和影响因子,证明了臭氧系统用于净化太平洋牡蛎中的E.coli是有效的。     

臭氧水与副干酪乳杆菌Z21联合处理对绿豆芽中大肠杆菌O157:H7的抑制机制

为研究臭氧水联合副干酪乳杆菌Z21发酵上清液对绿豆芽中大肠杆菌O157:H7的杀菌效果、细胞结构影响和生物膜清除作用,本实验对人工污染大肠杆菌O157:H7的绿豆芽进行联合处理,选出最优的杀菌条件,采用流式细胞仪、扫描电镜、傅里叶红外光谱（Fourier-transform infrared spectroscopy,FT-IR）、拉曼光谱分析臭氧水联合Z21发酵上清液的杀菌机制;通过菌落计数及胞外聚合物分析,研究了臭氧水联合Z21发酵上清液对大肠杆菌O157:H7生物膜的清除效果。结果表明,1.5 mg/L臭氧水联合10%（v/v）Z21发酵上清液处理对大肠杆菌O157:H7杀菌效果最佳,菌落总数减少了2.81 lg CFU/g;与对照组相比,联合处理破坏了大肠杆菌O157:H7细胞壁和细胞膜中的多糖,脂质和蛋白质结构,增加了细胞膜的通透性,改变了菌体形态。联合处理对生物膜有良好的清除效果,显著降低了生物膜的胞外聚合物含量（P<0.05）。本研究为大肠杆菌生物膜的清除及农产品防腐保鲜提供了理论依据。     

电解式臭氧水对盐渍青菜中微生物及风味的影响

利用电解式臭氧水对盐渍青菜进行脱盐处理,探讨臭氧水对盐渍青菜中病原/腐败微生物、理化指标和风味成分的影响。 通过平板计数,检测到质量浓度为6 mg/L的臭氧水流水处理盐渍青菜10 min后,对阴沟肠杆菌（Enterobacter cloacae）、大肠杆菌（Escherichia coli）、单核增生李斯特氏菌（Listeria monocytogenes）和金黄色葡萄球菌（Staphylococcus aureus）的杀灭率均可达到100%。 臭氧处理对盐渍青菜中维生素C含量有明显的降解作用,但对青菜中还原糖和总糖含量无显著影响（P＞0.05）。 气相色谱-质谱法检 测未处理、臭氧水和自来水各处理10 min后盐渍青菜中可挥发性风味成分分别为67、59和39种,并且臭氧处理后盐渍青菜中醛类和 烯类化合物增多。 研究结果表明,臭氧水脱盐工艺能有效杀灭盐渍青菜中的病原/腐败微生物,对盐渍青菜的风味有一定影响,但不 同于自来水处理。     

Transmission electron microscopic analysis showing structural changes to bacterial cells treated with electrolyzed water and an acidic sanitizer

The effects of various sanitizers on the viability and cellular injury to structures of Escherichia coli and Listeria innocua were investigated. A food grade organic acidic formulation (pH 2.5) and acidic, neutral, and basic electrolyzed water [AEW (pH 2.7, oxidation reduction potential; ORP: 1100 mV, free available chlorine; FAC: 150 ppm), NEW (pH 6.9, ORP: 840 mV, FAC: 150 ppm), BEW (pH 11.6, ORP: -810 mV)] were used to treat E. coli and L. innocua cells. After 10 min of exposure to the sanitizers, changes to the bacterial numbers and cell structures were evaluated by plate counting and transmission electron microscopy (TEM), respectively. It was concluded from the results that the sanitizers reduced the E. coli cells between 2 and 3 log CFU/mL. Except for the BEW treatment, reductions in L. innocua population were greater (>1 log CFU/mL) than that of E. coli for all treatments. Data from the TEM showed that all sanitizers caused changes to the cell envelope and cytoplasm of both organisms. However, smaller changes were observed for L. innocua cells. Decrease in the integrity of the cell envelope and aggregation of the cytoplasmic components appeared to be mainly because of exposure to the sanitizers. The organic acid formulation and AEW were the most effective sanitizers against bacterial cells, indicating that penetration of acidic substances effectively caused the cell inactivation. PRACTICAL APPLICATION: An understanding of the method in which E-water and an acidic sanitizer cause injury to E. coli and L. innocua would be helpful in selecting an effective chemical agent as a food safety tool. This will allow a scientist to target similar microorganisms such as food borne bacteria with structures that are vulnerable to the sanitizer.     

Effect of gaseous ozone and hot water on microbial and sensory quality of cantaloupe and potential transference of Escherichia coli O157:H7 during cutting

The effect of gaseous ozone and hot water, alone or in combination, on the sensory and microbial quality of cantaloupe melon was investigated. Escherichia coli O157:H7 transmission from the rind to edible melon flesh during cutting practices was also investigated. Four different treatments consisting of hot water (75 degrees C, 1min), gaseous ozone (10,000ppm, 30min), gaseous ozone supplied by carbon monoxide gas and the combination of hot water and gaseous ozone were evaluated. Sensory quality and growth evolution of aerobic mesophilic and psychrotrophic bacteria, coliforms and molds were studied. In general, hot water, gaseous ozone, and the combination of hot water and gaseous ozone were effective in reducing total microbial population. The combination of hot water and gaseous ozone was the most effective treatment to control microbial growth achieving 3.8, 5.1, 2.2 and 2.3log reductions for mesophilic and psychrotrophic bacteria, molds and coliforms, respectively. However no significant differences were observed between gaseous ozone and gaseous ozone supplied by with carbon monoxide gas. There was no evidence of damage in melons treated with hot water, ozone or their combination and they maintained initial texture and aroma. Therefore, the combination of hot water and gaseous ozone may be an efficient and promising treatment for controlling microbial growth and maintaining sensory quality of melons.