微酸性电解水对受鸡粪液污染鸡蛋表面沙门氏菌的喷雾消毒效果

为验证仅采用微酸性电解水（Slightly Acidic Electrolyzed Water,SAEW）对污染鸡粪液鸡蛋进行喷雾清洗和消毒,能否缓解鸡粪等有机物对消毒效果干扰问题,同时找出最佳有效氯浓度和消毒时间。该研究采用喷雾方式,按先清洗后消毒的流程对比双蒸水（H2O）+H2O组（清洗和消毒都用灭菌过的H2O）、碱性电解水（Electronized Reduced Water,ERW）+ERW组（清洗和消毒都用ERW）、H2O+SAEW组（先用灭菌过的H2O清洗,再用SAEW消毒）、ERW+SAEW组（先用ERW清洗,再用SAEW消毒）、SAEW+SAEW组（清洗和消毒都用SAEW）等方式对污染鸡粪液鸡蛋表面沙门氏菌的杀灭效果,并采用多元非线性回归拟合杀菌模型,评估了有效氯浓度和消毒时间对SAEW+SAEW组和ERW+SAEW组的影响。结果发现,仅采用SAEW对污染鸡粪液的鸡蛋进行喷雾杀菌方式,可有效避免鸡粪液对SAEW杀菌效果干扰,当采用SAEW（ACC = 25 mg/L）进行喷雾清洗和消毒,清洗时间10 s,消毒时间18 s时,可完全杀灭污染鸡粪液鸡蛋表面沙门氏菌,杀菌值达到6.26 lg cfu/个;SAEW+SAEW组模型决定系数和调整决定系数分别为0.933和0.930,ERW+SAEW组分别为0.926和0.923;验证试验中,SAEW+SAEW组和ERW+SAEW组实际值和预测值的相关系数分别为0.97和0.95;模型成立,该研究可为SAEW在鸡蛋消毒中的应用提供参考。     

微酸性电解水对污染轮胎表面的模拟消毒优化

为降低鸡场肠病原体疫病传播风险和兽药残留,通过响应面中和设计法,该试验评估了微酸性电解水(p H值5.85~6.53)对大肠杆菌和沙门氏菌混合污染轮胎的消毒效果,并探讨了清洗时间,消毒时间及有效氯浓度3个因素对微酸性电解水消毒效果的影响及相互作用规律,同时建立二次多项回归模型,并对消毒工艺进行优化。结果表明,3个因素皆对消毒效果有显著影响(p0.0001),且各因素影响大小为有效氯浓度消毒时间清洗时间;模型决定系数和调整决定系数分别为0.984和0.969,验证试验中,试验值与预测值的相关系数为0.97;消毒时间5 min、清洗时间4 min、有效氯浓度140 mg/L时,可以达到1.38 log10 cfu/cm2的杀菌数。该研究为微酸性电解水消毒提供了参考,并证明了微酸性电解水在畜牧业的应用潜力。     

中性氧化电解水对卷心菜的杀菌作用与机理

酸性氧化电解水作为一种高效杀菌剂,但因其低pH值,所以在制备和使用过程中会产生少量氯气污染、对金属材料有一定腐蚀性,影响其在农业和食品领域中应用。中性氧化电解水的pH值接近中性,可以克服以上缺点。该文考察了有效氯浓度相近的中性氧化电解水、84消毒液、H2O2和NaClO对卷心菜的杀菌作用,结果表明NEOW具有高效的杀菌作用,杀菌效果优于84消毒液、H2O2和NaClO,当NEOW有效氯含量为24.52 mg/L时,对大肠杆菌的杀菌效率为95.81%,杀灭对数值为1.38;当有效氯含量为63.42 mg/L时,对大肠杆菌的杀菌效率为98.92%,杀灭对数值为1.97。另外,研究了中性氧化电解水杀菌作用的影响因素,结果表明在一定范围内增加有效氯含量会提高杀菌效果,但有效氯含量过高时,杀菌效率反而降低,原因在于有效氯增高时,氧化电解水pH值增加,有效氯存在形式发生改变。在有效氯含量较高时,氧化电解水pH值的改变对杀菌效果影响不大;但当有效氯含量较低时,pH值越高,杀菌效果越差。此外,还考察了杀菌时间对杀菌效果的影响,杀菌时间增加有利于提高杀菌效率。该试验研究为中性氧化电解水的食品杀菌应用研究提供了理论依据,还通过其杀菌作用影响因素的研究揭示了其杀菌机理,提出了最优的杀菌条件。     

蛋种鸡场中性电解水带鸡喷雾消毒试验研究

养殖场的定期消毒是工程防疫的一项重要措施。该文针对强酸性电解水（高氧化还原电位水）的低pH值 （＜2.7）、腐蚀性大、制造成本高、不适合畜禽养殖中的应用等问题,试验研究了中性电解水（pH 6.5～8.5）与常用消毒剂（速洁和聚维酮碘等）对蛋种鸡场的带鸡喷雾消毒效果。考察了不同有效氯浓度、风机停开时间（作用时间）和喷嘴直径下中性电解水对鸡舍空气的杀菌效果。结果表明,不同作用时间下,中性电解水带鸡喷雾消毒效果均优于含过氧乙酸/双氧水的速洁消毒剂和聚维酮碘,且消毒效果随着有效氯浓度的升高而增强;较小的喷嘴直径（50 μm）带鸡喷雾消毒,可以提高有效氯利用率,对空气的杀菌率高。采用有效氯浓度为160 mg/L及以上的中性电解水带鸡消毒,喷雾结束后风机停开5 min具有较好的消毒效果。因此,中性电解水可以用于种鸡舍带鸡消毒,对发展无害化绿色健康养殖具有重要意义。     

微酸性电解水对虾仁的杀菌效果及其动力学

为探明微酸性电解水(slightly acidic electrolyzed water,SAEW)对南美白对虾(Litopenaeus vannamei)虾仁表面杀菌效果及其动力学规律,选取料液比1:4、1:10、1:20,将虾仁分别浸洗杀菌2、5、10 min,对杀菌过程中虾仁表面及SAEW残存液中总菌落数,与有效氯质量浓度(available chlorine concentration,ACC)的变化进行测定,建立ACC衰减与微生物减灭的动力学模型,并通过颜色、硬度、pH值,及水分横向弛豫行为分析,探讨SAEW杀菌处理对虾仁品质的影响。结果表明SAEW对虾仁表面大肠杆菌有较强杀菌效果,并随处理时间的延长、作用量的增大,SAEW的杀菌效力不断增强,处理5 min时,随着料液比的增加,虾仁表面菌落数从最初的6.6 l(CFU/mL),依次降到5.0、4.7、4.4 lg(CFU/mL),料液比为1:20时,静置浸洗10 min后,虾仁表面菌落数由最初的6.6 lg(CFU/mL)降至3.9 lg(CFU/mL);同时SAEW浸洗液中残存菌落数也随处理时间的延长、作用量的增大,而不断减少,在处理2、5和10 min时,SAEW中的残存菌落数分别为4.18、3.47、2.78 lg(CFU/mL),处理时间为5 min时,随料液比的增加,SAEW中的残存菌落数分别为3.47、2.78、2.65 lg(CFU/mL);同时SAEW中ACC的消耗随处理时间的延长、而不断变大,杀菌处理5、10 min时,ACC质量浓度从初始的20.53 mg/L分别降至7.79、10.97 mg/L。动力学分析表明:SAEW在杀灭虾仁表面大肠杆菌的过程中,ACC的衰减可以用一级动力学模型描述,拟合后决定系数R2均大于0.9,而微生物的减灭遵循更为复杂的动力学模型;此外经过SAEW杀菌处理的虾仁,其颜色、pH值、硬度、以及水分的横向弛豫行为,与未处理样品相比,基本没有显著性变化。相关结果能为SAEW在水产品加工过程中的应用提供技术指导,同时也有助于SAEW杀菌技术理论的完善。     

孵化场微酸性电解水冲洗消毒效果试验研究

孵化场出雏器和出雏筐的冲洗消毒是孵化生产的重要环节,该文针对孵化场使用化学消毒剂会导致化学残留、消毒效果低和病菌微生物耐药性增加等问题,将有效氯质量浓度为60～100mg/L微酸性电解水应用于出雏器内壁、地面和出雏筐的冲洗消毒,并与常规化学消毒剂(50 mg/L聚维酮碘溶液和50 mg/L苯扎溴铵溶液)进行冲洗消毒效果对比研究。结果表明,有效氯质量浓度为60～100mg/L的微酸性电解水冲洗消毒可以有效杀灭出雏器内壁、地面和出雏筐表面的总菌(需氧菌总数)、大肠杆菌和金黄色葡萄球菌,且杀菌效果随有效氯质量浓度和冲洗消毒时间的增加而提高。有效氯质量浓度为100mg/L的微酸性电解水冲洗消毒3min对出雏器内壁和地面总菌的杀菌率分别为93.9%和85.6%,且显著高于50 mg/L的聚维酮碘溶液的杀菌率(73.1%和69.6%)和50 mg/L的苯扎溴铵溶液的杀菌率(76.6%和74.5%)(P 0.05);对出雏筐表面冲洗消毒40s,杀菌率为79.6%。较常规化学消毒剂,微酸性电解水冲洗消毒可显著提高对出雏器和出雏筐的消毒效果,同时还具有广谱、无残留等优点,是孵化场出雏器和出雏筐表面消毒的良好替代消毒剂。     

樱桃番茄清洗杀菌工艺优化

清洗杀菌可提高樱桃番茄的食用安全和商业价值,使得樱桃番茄外观口味俱佳、保存期更长、好果质量分数更高,该研究以宁夏樱桃番茄为试验对象,利用多槽自动输送式蔬菜清洗机和次氯酸杀菌消毒制备设备进行清洗和杀菌,通过清洗杀菌试验的测试结果来确定合理的清洗和杀菌工艺参数。试验结果表明:清洗机清洗樱桃番茄单槽喂入量最大值为15kg;清洗用时170s即可达到理想的清洗效果,洗净质量分数可达99.3%;杀菌水有效氯浓度为100μg/mL,消毒时间为85s,可使樱桃番茄表面菌落总数降低1.128个对数值;用有效氯质量100μg/mL次氯酸杀菌水清洗后的果实,在10℃的冷库环境保存下,18d后好果质量分数仍能达到77%。本研究结果可为工业化生产中樱桃番茄清洗杀菌工艺的提供参考。     

微酸性电解水雾滴沉积量及粒径对畜牧环境杀菌效果的影响

微酸性电解水为畜牧业初步应用的环保消毒剂,为精确喷雾以减少残留,先利用称重法测量它在不同孔径及压力下的雾滴沉积量,研究该沉积量对杀菌效果影响,确定对衣物表面消毒最佳单位沉积量。随后对比不同雾滴粒径对衣物表面细菌的杀灭效果,以确定喷雾消毒方式。结果表明,不同压强及喷头下,雾滴沉积量具显著性差异(P0.05)。且呈中间密集、两端稀疏特征;随压强及孔径增大,两端呈先升后降趋势。微酸性电解水(pH值6.15~6.35,有效氯浓度135 mg/L)对衣物表面消毒最佳沉积量为1.49×10~(-2)g/cm~2。大雾滴(80~90μm)杀菌率在同时间下显著高于小雾滴(P0.05),但其空间分布均匀性显著(P0.05)低于小雾滴(≤30μm)。雾滴粒径及沉积量对微酸性电解水杀菌效果具显著影响(P0.05)。     

辐照处理对干制海兔杀菌效果及其营养成分的影响

以干制海兔为原料,研究辐照对其杀菌效果及营养成分的影响。结果表明：辐照对干制海兔杀菌效果明显,4kGy剂量辐照后,菌落总数由初始的107cfu/g降低到<103cfu/g,霉菌和金黄色葡萄球菌<10cfu/g,大肠菌群<10MPN/100g,辐照前后均未检出沙门氏菌。从统计分析的结果看,虽然辐照组中蛋白质、脂肪及大部分不饱和脂肪酸的含量都显著高于或低于CK中的含量,但和水分、碳水化合物、VA等一样,它们的含量与辐照剂量没有显著的线性关系,即它们的含量不因辐照剂量的增加显著增加或减少;辐照对灰分、氨基酸（除胱氨酸和脯氨酸）及VB2和VB3的含量没有明显的影响,对VE的影响显著,当辐照剂量为2kGy时,VE的含量高于CK中的含量,而剂量继续增大时其含量却不断减少且都低于CK中的含量。     

全蛋液的高压CO2杀菌工艺参数优化

为了达到杀灭蛋液中沙门氏菌和避免热巴氏杀菌引起鸡蛋蛋白变性的目的,该研究采用高压CO_2(high pressure carbon dioxide,HPCD)对全蛋液中沙门氏菌进行冷杀菌。通过单因素试验分析CO_2压力、杀菌温度、杀菌时间和搅拌速度对全蛋液中沙门氏菌的杀菌效果,并利用Box-Behnken响应面设计建立了沙门氏菌杀灭的二次多项回归模型。得出最佳杀菌工艺为:在CO_2压力为30 MPa、温度为40℃、时间为60 min、搅拌速度为125 r/min的条件下,能够使全蛋液中3×10~6~3×10~7 CFU/m L的沙门氏菌完全杀灭。同时还比较了巴氏杀菌和HPCD杀菌对全蛋液的货架期、功能特性的影响。研究结果表明:与巴氏蛋液比较,HPCD使全蛋液货架期延长至39 d;起泡能力和起泡稳定性分别提高了53.63%和2.38%;乳液Zeta电位提高至7.66 mV,提高了乳液稳定性;全蛋液的粘度、粒度储能模量和损耗模量分别降低,呈现粘弹性性流体的特性。该研究结果可为HPCD杀菌技术应用蛋液产品提供参考。     

Plant extracts, spices, and essential oils inactivate Escherichia coli O157:H7 and reduce formation of potentially carcinogenic heterocyclic amines in cooked beef patties

Meats need to be heated to inactivate foodborne pathogens such as Escherichia coli O157:H7. High-temperature treatment used to prepare well-done meats increases the formation of carcinogenic heterocyclic amines (HCAs). We evaluated the ability of plant extracts, spices, and essential oils to simultaneously inactivate E. coli O157:H7 and suppress HCA formation in heated hamburger patties. Ground beef with added antimicrobials was inoculated with E. coli O157:H7 (10(7) CFU/g). Patties were cooked to reach 45 °C at the geometric center, flipped, and cooked for 5 min. Samples were then taken for microbiological and mass spectrometry analysis of HCAs. Some compounds were inhibitory only against E. coli or HCA formation, while some others inhibited both. Addition of 5% olive or apple skin extracts reduced E. coli O157:H7 populations to below the detection limit and by 1.6 log CFU/g, respectively. Similarly, 1% lemongrass oil reduced E. coli O157:H7 to below detection limits, while clove bud oil reduced the pathogen by 1.6 log CFU/g. The major heterocyclic amines 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were concurrently reduced with the addition of olive extract by 79.5% and 84.3% and with apple extract by 76.1% and 82.1%, respectively. Similar results were observed with clove bud oil: MeIQx and PhIP were reduced by 35% and 52.1%, respectively. Addition of onion powder decreased formation of PhIP by 94.3%. These results suggest that edible natural plant compounds have the potential to prevent foodborne infections as well as carcinogenesis in humans consuming heat-processed meat products.     

Green-leaf-derived C6-aroma compounds with potent antibacterial action that act on both Gram-negative and Gram-positive bacteria

All eight C6-aliphatic alcohol and aldehyde compounds in naturally occurring green leaves showed bacteriostatic effects against Staphylococcus aureus IFO 12732, methicillin-resistant S. aureus, Escherichia coli IFO 3301, E. coli O157:H7, and Salmonella enteritidis, with bacteriostatic activities of less than 12.5 microg mL(-1). In this study, the susceptibility of Gram-positive bacteria tested was observed to be greater than that of Gram-negative bacteria. The bactericidal action of the aldehyde compounds was found to be much stronger than that of the alcohol compounds under both liquid and gaseous conditions. The most effective compound was (3E)-hexenal at concentrations of 0.1 and 1 microg mL(-1), which killed 2.1 x 10(5) cfu mL(-1) of S. aureus IFO 12732 and 1.4 x 10(5) cfu mL(-1) of E. coli IFO 3301, respectively, by direct contact with the compound. Lethality of (3E)-hexenal against S. aureus IFO 12732 and E. coli IFO 3301 was also observed as a result of gaseous contact at concentrations of 3 and 30 microg mL(-1), respectively. The bactericidal effects of 30 microg mL(-1) (3E)-hexenal were thoroughly maintained throughout periods of 2 days and 1 day against S. aureus IFO 12732 and E. coli IFO 3301, respectively, by a complex formation with alpha-cyclodextrin.     

Glycopeptide derived from hen egg ovomucin has the ability to bind enterohemorrhagic Escherichia coli O157:H7

Ovomucin glycopeptide (OGP) was prepared by size exclusion chromatography after Pronase digestion of hen egg ovomucin, and the binding of OGP to foodborne pathogens (Bacillus cereus,Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enteritidis, Salmonella typhimurium, and Staphylococcus aureus) was investigaed. Binding assays with biotinylated bacteria as probes in microtiter plates showed that OGP bound to only E. coli O157:H7 among these foodborne pathogens. Periodate treatment markedly reduced the binding ability, indicating that E. coli O157:H7 bound to carbohydrate moieties of OGP. Lectin blot analysis with Maackia amurensis (MAA) and Sambucus nigra (SNA), which are specific for oligosaccharides containing sialic acid, revealed their binding sites in OGP were similar to the E. coli O157:H7 binding sites that were probed with biotinylated E. coli O157:H7 after Western blotting of OGP. Sialydase treatment of OGP abolished its ability to bind E. coli O157:H7, demonstrating that sialic acid played an important role in the binding. These results suggest that OGP has E. coli O157:H7-specific binding sites that consist of sialic acid. On the basis of these properties, OGP has the potential to be an ingredient with a protective effect against E. coli O157:H7 infection and to be a novel probe for the detection of E. coli O157:H7 in the food hygiene field.     

规模化鸡场饮水系统添加微酸性电解水杀菌效果试验

重视饮水系统卫生质量安全是预防鸡群发病的一个重要环节.规模化鸡场饮水管道全封闭、内部清洁困难,而为提高饲料转化率和抗应激能力,普遍通过饮水系统添加多维等产品,加速了饮水系统污染、细菌超标等.目前鸡场饮水系统常用的反向冲洗水线、清洁剂洗涤清洁方式,存在杀菌不彻底、影响蛋鸡肠道微生物和废水过度排放等严重问题.该文研究了添加多维溶液对水线内水质影响变化规律,并对比研究了添加多维溶液后,冲洗水线、添加微酸性电解水2种方式对鸡场饮水系统的杀菌规律.结果表明:饮水系统中添加多维溶液2、4、6、12、24、36、48、72 h后,水线内细菌浓度总数的对数值分别增加9.96％、5.33％、6.04％、7.47％、4.98％、5.69％、4.27％、4.98％;冲洗水线能冲洗掉饮水管壁附着沉积层,一定程度上减少饮水中细菌总数,但饮水中细菌浓度总数仍高于中国饮水卫生质量标准;添加余氯0.3 mg/L的微酸性电解水24 h后,饮水管线中细菌浓度降低34.7％,48 h后水线中细菌浓度的对数值维持为(1.83±0.05 lg(CFU/mL)),添加余氯0.3 mg/L微酸性电解水使水线内细菌浓度总数显著降低(P＜0.01),达到中国饮水卫生标准,且规模化鸡场饮水系统添加微酸性电解水作为杀菌消毒剂可减少废水产生排放.该研究结果为鸡场饮水系统选择长期添加使用的消毒剂提供了参考依据.     

Survival of various ERIC-genotypes of Shiga toxin-producing Escherichia coli in well water

Recently, there has been a surge of interest in understanding the survival of Shiga toxin-producing Escherichia coli (STEC) in aquatic environments. Fifteen strains of STEC were monitored, individually, in untreated well water samples incubated at 10 and 22^{^}C for 56 days. The strains were selected from three serogroups (O26, Ol11 and O157) and represented five distinct ERIC (enterobacterial repetitive intergenic concensus)-genotypes. The microcosms were prepared in triplicate and inoculated at an initial cell density of about 7.0 log CFU/ml well water. At 10^{^}C, the cell density of five STEC strains fell below the detection limit of 0.8 log CFU/ml by day 56. Of the ten persisting strains, four showed superior survival with cell densities decreasing to an average of about 5 log CFU/ml while the remaining six strains showed moderate levels of survival, decreasing to an average cell density of about 3 log CFU/ml. At 22^{^}C, strain H32 (genotype I) and H15 (genotype B) persisted at 1.1 log CFU/ml and 2.2 log CFU/ml in 56 days, respectively. The other 13 STEC strains dropped below the detection limit between weeks 3 to 8. The 15 strains demonstrated highly variable levels of survival with no correlation between ERIC-genotypes or serogroups and the strains' ability to persist in the well water samples. Although strain H32 (O157:H7) persisted significantly longer than strain H22 (O157:H7) in natural well water at both 10 and 22^{^}C, both strains survived equally well in sterile well water, indicating that individual STEC strains vary in their ability to compete with background microbial populations.     

Effect of decontamination agents on the microbial population, sensorial quality, and nutrient content of grated carrots (Daucus carota L.)

Several decontamination agents including water, sodium hypochlorite, peroxyacetic acid, neutral electrolyzed oxidizing water, and chlorine dioxide gas were tested for their effectiveness to reduce the natural microflora on grated carrots. Microbial reductions of the total aerobic count obtained after the different treatments varied between 0.11 and 3.29 log colony-forming units (cfu)/g. Whether or not a decontamination step induced significant changes in the sensory attributes of grated carrots is highly dependent on the type and concentration of disinfectant. To maintain the nutritional value, the influence of the decontamination agents on carotenoid content, alpha-tocopherol content, total phenols, and antioxidant capacity was studied. Besides the part of the nutrients that was leached away from the cutting areas by water, the nutrient losses caused by adding sanitizers were rather limited. Compared with the untreated carrots alpha-tocopherol content was, however, significantly reduced when 250 ppm of peroxyacetic acid (-80%) or 200 ppm of sodium hypochlorite (-59%) was used. Additional losses in carotenoid content were caused by contact with chlorine dioxide gas (-9%). On the condition of an optimized decontamination process toward time and concentration, the microbial quality of fresh-cut carrots could be improved without negatively influencing their sensory quality and nutrient content.