辐照对食用槟榔的杀菌效果及品质的影响

以食用槟榔为研究对象,研究辐照对其杀菌效果及品质的影响。结果表明:辐照对食用槟榔杀菌效果明显,当辐照剂量为3.65kGy时,食用槟榔的菌落总数由初始的5.8×105CFU·g-1降低到1.1×103CFU·g-1,霉菌数小于10CFU·g-1,大肠菌群数由4.6×102MPN·g-1降低到3 MPN·g-1以下;当辐照剂量为8.45kGy时,菌落总数、霉菌和大肠菌群均未检出。辐照对食用槟榔中水分、灰分、蛋白质和脂肪含量的影响不显著,对总糖、总酚含量和pH值的影响显著。9.77kGy以下的辐照剂量不会对食用槟榔的色泽、气味、滋味与口感及可接受性产生明显的影响。4~10kGy的辐照剂量能够很好的满足食用槟榔产品的卫生要求。     

西瓜汁的高强度脉冲磁场杀菌试验研究及杀菌机理分析

该文旨在研究液态食品的高强度脉冲磁场杀菌技术，探讨高强度脉冲磁场对微生物细胞产生的生物效应。以西瓜汁的杀菌为例，研究了磁场强度和脉冲数对杀菌效果的影响。研究结果表明：随着场强和脉冲数的增加，从整体上讲杀菌效果增强；在场强为2.53 T、脉冲数为20时，杀菌效果最好。当脉冲数为40时，磁场强度对杀菌效果的影响为单调增加；当磁场强度为4.22 T时，脉冲数对杀菌效果的影响为单调增加。但在某些参数下杀菌效果出现反弹现象，其原因有待进一步探讨。从脉冲磁场导致细胞跨膜电位、感应电流、带电粒子洛仑兹力、离子能量等参数变化的角度，描述了脉冲磁场对微生物细胞产生的生物学效应，分析了致使细胞结构被破坏、正常生理活动受阻碍的机理。     

辐照对软罐头包装凤爪的杀菌作用和品质的影响

使用0、3、5、10kGy的60Coγ射线辐照软罐头包装凤爪,分别在贮存0、30、60、90d时检测样品中的菌落总数、大肠菌群、致病菌、TBARS值,并进行了感官评价试验.结果表明,贮藏90d后,辐照组的菌落总数分别为6.1×103、1.4×103、765cfu/g,在整个贮存期间均低于对照组,且未检出大肠菌群和致病菌...     

微波和巴氏杀菌后番茄汁品质动力学

为了解杀菌方式对番茄汁品质和货架期的影响,研究了经巴氏杀菌（85℃,4 min）和微波杀菌（800 W,20 s）番茄汁的品质动力学,均使其加工到无菌状态,然后在不同恒温条件下（0、4、10、25、37℃）贮藏,每隔一段时间测定菌落总数、维生素C质量分数及色差值。结果表明：2种杀菌方式处理的番茄汁在贮藏期间,菌落总数增值速率,维生素C损失及褐变程度随贮藏时间的延长和贮藏温度的升高而增加,其中,褐变程度和维生素C损失率呈线性关系。0～10℃低温贮藏条件下,基于维生素C保留率微波杀菌的番茄汁与巴氏杀菌的相比,其货架期延长了9.1～17.5 d,而基于色泽变化程度货架期延长了14.9～71 d,25～37℃高温贮藏条件下,基于维生素C保留率和色泽变化程度2种杀菌方式后番茄汁的货架期差别不显著。基于菌落总数作为评价指标,2种杀菌方式之间差别不显著,为1～2 d。应用建立的货架期预测模型,以菌落总数和维生素C质量分数作为评价指标,可以快速准确地预测0～37℃贮藏范围内微波处理后番茄汁的货架期,准确率达到90%。以菌落总数作为评价番茄汁货架期的最终标准,0～10℃低温条件下,经微波杀菌的番茄汁推荐其货架期为5～8 d,经巴氏杀菌的番茄汁推荐其货架期为5～9 d。为微波技术在果汁加工及贮藏中的应用提供技术依据。     

微生物不同生长期及介质参数对脉冲磁场杀菌效果的影响

利用脉冲磁场对大肠杆菌和金黄色葡萄球菌在不同生长阶段、不同介质温度及pH值的情况下进行杀菌试验，结果表明：这两种菌在对数生长期比稳定生长期和延迟生长期对磁场更敏感，两种细菌在对数生长期的后期杀菌效果均出现反弹变差的现象，反弹趋势延长至稳定生长期，并趋于平缓；介质温度越高，脉冲磁场杀菌效果越好，但该温度远低于热致死温度；介质pH值越偏中性，杀菌效果越差，pH值小于5时，杀菌效果较好。     

猪场沼液絮凝上清液的紫外线杀菌效果

猪场沼液中含有大量的微生物,为确保其排放或循环利用的卫生和环境安全,应对其进行有效的杀菌处理,目前国内沼液杀菌相关的研究缺乏。由于猪场沼液原液的色度和浊度很高,紫外线透过率很低,采用紫外线杀菌前需要对其进行预处理。该研究采用絮凝方法处理猪场沼液,对所获取的不同透射率沼液絮凝上清液进行杀菌试验,试验以细菌总数、大肠菌群和粪大肠菌群的数量变化及其杀菌率为指标,在4种沼液絮凝上清液透射率(0.01%、0.69%、3.78%和8.54%)、3种紫外线杀菌装置内水深(1、2和3 cm)和5种水力停留时间(1、5、10、15、20和30 min)试验条件下,探讨紫外线对沼液絮凝上清液杀菌的可行性及其运行效果。结果表明,絮凝上清液透射率(T254)、紫外线杀菌装置内水深和水力停留时间等因素对紫外线的杀菌效果均有极显著影响(P0.01),3种因素之间均有极显著的交互作用(P0.01)。试验紫外线灯管强度为395μW/cm2,当沼液絮凝上清液的透射率为0.69%、水力停留时间15 min和紫外线杀菌装置内水深2 cm时,紫外线对细菌总数、大肠菌群和粪大肠菌群的杀菌率分别为(99.99±1.20)%、(99.99±1.43)%和(100.00±0.01)%,使沼液絮凝上清液中粪大肠菌群的数量从3.9×106个/L下降至检出限(3个/L)以下,紫外线杀菌处理出水达到现行国家标准的无害化卫生要求,该研究可能为沼液的紫外线杀菌技术的深入研究和沼液安全循环利用提供参考。     

干制海鱼的辐照杀菌剂量的确定

研究了γ射线辐照干制黄线鱼、马步鱼、蓝鳕鱼的杀菌效果及其对海鱼蛋白质、脂肪、微量元素、重金属、水分和灰分含量的影响。结果表明:干制海鱼的辐照灭菌效果明显,在2.55~13.65kGy范围内,3kGy可以使菌落总数降至104cfu/g以下;致病菌未检出;5kGy可以将大肠菌群降至30MPN/100g以下,符合动物性水产干制品国家卫生标准。辐照后干制海鱼中的蛋白质含量高于对照。但经统计分析,辐照前后蛋白质与脂肪的含量均没有显著差异。辐照剂量为10.4kGy以上时,尽管干制海鱼中的水分含量略微降低,部分微量元素的含量有所增加,但微量元素、污染物、水分及灰分含量总体没有显著影响。综合试验结果,确定干制海产品辐照杀菌的适宜剂量范围为5~10kGy。     

射频加热杀灭浓缩苹果汁中鲁氏接合酵母的工艺优化

为研究射频对苹果汁中鲁氏接合酵母杀灭作用,该文以鲁氏接合酵母为试验菌株,通过单因素试验分析了射频加热时间、极板间距、果汁体积、果汁可溶性固形物对杀菌效果及果汁升温速度的影响。在固定果汁可溶性固形物为70%的条件下,通过响应面试验,建立了鲁氏接合酵母菌落总数降低对数值的二次多项数学模型,确定了在极板间距为110 mm、果汁体积40 m L、果汁可溶性固形物70%的条件下射频加热处理70 s,可以使果汁中鲁氏接合酵母菌落总数下降6个对数值以上。研究比较了相同样品经射频和传统水浴杀菌达到相同杀菌效果时,处理前后果汁理化指标及风味变化程度,结果表明,射频(70 s)比水浴(330 s)能更快达到杀菌目的,同时对果汁品质以及风味的影响(P0.01)小于水浴处理。研究结果为射频杀菌方面的深入研究及实际应用提供了参考。     

冷冻水产品辐照杀菌工艺剂量的确定

根据国内外学者的研究结果,和国外辐照冷冻水产品的卫生标准和工艺规范中的规定,可归纳出当辐照前产品菌落总数低于5×106cfu/g时,用4~7kGy辐照处理冷冻水产品,能够保证辐照后产品的菌落总数低于5×104cfu/g,且无致病菌检出。该工艺剂量的确定对冷冻水产品辐照杀菌工艺的编制具有十分重要的意义。     

神经网络优化牡蛎的高密度CO2杀菌工艺

为了研究高密度二氧化碳(DPCD)对牡蛎的杀菌效果,利用神经网络对DPCD杀菌工艺参数进行优化,建立了杀菌工艺的神经网络模型.研究结果表明:当温度在(50-5)℃时,压力和时间相应调整,即可在低压短时间内达到较好的杀菌效果;在低于45℃条件下,温度和压力对DPCD杀菌效果影响较大;在高于45℃条件下,温度、压力和处理时间对DPCD杀菌效果的影响较小;在45或55℃和15 MPa条件下,DPCD直接对牡蛎肉处理30 min,其杀菌效果与100℃沸水煮2 min相当,菌落总数下降了3.0个对数以上,达到了水产熟制品卫生标准.该研究为牡蛎DPCD杀菌提供了理论依据.     

电子束辐照对鱿鱼发酵食品及其配料微生物和感官特性的影响

为使电子束辐照在Jeotkal食品产业中得到广泛利用,对鱿鱼Jeotkal发酵食品及配料实施电子束辐照后,分析了鱿鱼Jeotkal发酵食品及配料的微生物和官能特性。结果表明,电子束处理前鱿鱼Jeotkal好氧菌数为2.88logCFU/g,经5kGy处理后,下降为1.76logCFU/g;酵母和霉菌及大肠杆菌初期污染度分别为3.04logCFU/g和4.20logCFU/g,经5kGy辐照后,下降到1.27和1.34logCFU/g,降低2～3log cycle。辣椒粉辐照处理前好氧菌数为4.07logCFU/g,酵母菌和霉菌为3.91logCFU/g,大肠杆菌为4.34logCFU/g。辣椒粉经5kGy辐照后,好氧菌及酵母菌和霉菌显示为ND。蒜糜中初期好氧菌数为4.41logCFU/g,酵母及霉菌为4.48logCFU/g,大肠杆菌为4.32logCFU/g;经5kGy电子束辐照后好氧菌、酵母及霉菌、大肠杆菌都显示为ND。电子束不仅对鱿鱼Jeotkal微生物具有显著的杀菌效果,而且没有引起鱿鱼Jeotkal的pH和官能特性的变化。因此,电子束杀菌技术在低盐或发酵食品储藏工艺中具有很好的应用前景。     

不同光质补光对日光温室黄瓜产量与品质的影响

本试验采用不同的光质灯(蓝光、红光、UV-A、UV-B)对温室内黄瓜进行定时补光,研究不同补充光质对黄瓜果实Vc、蛋白质、还原糖含量及产量的影响。结果表明UV-B、红光条件下黄瓜Vc含量较UV-A与蓝光高;各处理蛋白质含量顺序为蓝光>UV-A>UV-B>红光;蓝光照射下还原糖含量较红光、UV-A与UV-B高;日光温室内补充UV-A可明显地增加黄瓜的产量。     

Bacteriological and genetic assessment of game meat from Japanese wild boars

Bacterial tests were used to assess bacterial contamination of game meat from Japanese wild boars. The bacterial contamination of wild boar meat was less than that of domestic pork, as determined by aerobic plate counts (APC) and coliform counts. None of the meat examined in this study was contaminated by Salmonella or E. coli O-157. To detect adulteration by domestic pig meat or European wild boar meat, 46 samples of game meat sold as Japanese wild boar were examined genetically. A total of 17 samples showed genetic haplotypes of European and Asian domestic pigs in the D-loop of mitochondrial DNA (mtDNA), and 16 samples showed nuclear glucosephosphate isomerase-processed pseudogene (GPIP) genotypes of European domestic pigs. The European GPIP genotypes of these samples were confirmed by PCR-RFLP analysis. These results indicate that some game meat sold as Japanese wild boar is adulterated by cross-breeding between pigs and wild boars or by contamination with meat from domestic pigs or European wild boars.     

辐照对调味品和脱水蔬菜中大肠菌群杀灭效果的研究

6kGy辐照可以使调味品和脱水蔬菜中的大肠菌群最可能数 (MPN)符合国家卫生标准的要求。通过对 1 88个辐照过的调味品的检验 ,未发现在大肠菌群中出现耐辐射的新菌株。目前出现误判“大肠菌群超标”的原因主要是由于菌检技术不过关所致 ,其中复发酵和革兰氏染色挑菌不是来自同一菌株是造成误判的最主要原因。     

Investigations of pipe-borne pollution in Benin City,Nigeria

Two important environmental parameters could be identified as being the main causes of pipe borne water contamination in the City of Benin. These are the combined effects of rainfall and excessive construction work and, secondly, the lack or inadequacy of plumbing codes. To study the combined effects of rainfall and excessive construction on the contamination of water, samples were tested for total coliform using the multiple-tube fermentation test. Sites were chosen to allow for the comparison of the coliform counts in areas of comparatively insignificant construction to areas of excessive public construction. Results show that in the areas of heavy public construction, the curves for both the rainfall and the coliform counts in the consumer lines were skewed in the same manner. The peak rainfall was in September (437.I mm) which corresponds to peak coliform number in the consumer lines for both Zone A (62 coliforms/100 ml) and Zone B (60 coliforms/100 ml) for the same month. When compared to the area of insignificant public construction as shown in Zone C, rainfall had little or no effect on the coliform counts either at the pumping station or in the consumer line. The maximum number of coliforms recorded for the consumer line was 5/100 ml during the month of June. Results suggest that the high counts of coliforms in the Benin City water supply could be attributed primarily to the effects of construction which resulted in pipe breakage. During heavy rainfall and flooding, water under flood pressure enters the pipes through cracks, improperly tightened joints and damaged pipes. The improper enforcement of plumbing codes or lack of such codes was also identified as another cause of the water contamination as shown in Zone D. A study of the effects of water pipes passing through septic tank drain fields also shows that such effluents served as another source of major contamination. The highest recorded number for coliforms for the pipe-borne water just before entering the septic tank drain field was 12/100 ml and after it passed through the field the number had gone up to 60/100 ml. Artificial contamination of the septic tank effluents to try to detect leaks in the water pipes passing through the absorption field was investigated. The bacterial contaminant could be recovered in the pipe-borne water and the quantity was skewed in the same manner as total rainfall between periods of sampling.     

Bacteriological Changes Associated with Granular Activated Carbon in a Pilot Water Treatment Plant

Bacteriological analysis were performed on collected water samples from a conventional water treatment pilot plant in Cincinnati, Ohio in which granular activated carbon (GAC) has been used as the final process to assess the impact of GAC on the bacteriological quality and incidence of antibiotic resistant bacteria in water produced. Heterotrophic bacterial counts (HPC) at 20 °C was stabilized at 10² to 19⁴ cfu mL^-1 and did not markedly differ at different water treatment processes. On the other hand, slight reduction in HPC was observed for the effluent produced from sand filter and GAC contactors. Effluents produced from both the sand filter and GAC contactors showed 2 log reduction in coliforms count. Fecal coliform showed the same rate of reduction as a result of sand filtration, while it reached undetectable numbers in the effluent of GAC contactors. Subculturing the isolated strains in tryptic soy broth revealed that 61.3, 61.5, 12.6 and 8.5% of HPC at 28 °C, total coliforms and fecal coliform, respectively were non-culturable. In this case, R2A or R3A broth was used as subculturing media. The incidence of coliform resistant strains among isolates varied significantly according to the source of water samples. Multiple antibiotic resistance (MAR) was not always high in the same samples in which the overall resistance was high. The species composition varied considerably in different water samples. Selection for bacteria exhibiting resistance to antibiotic or antibiotics was observed under some experimental conditions using different doses of chlorine. The antibiotic resistance character was mostly transferable. As a conclusion, the use of GAC has no observable adverse effect on the bacteriological quality of the water produced from the pilot plant under investigation.     

Bacterial numbers and biomass in leachate and in subsoil of a submerged paddy field

By a leaching experiment with glass columns packed with submerged paddy soils, the relationships among numbers of total bacteria, total Gram-positive bacteria, culturare aerobic bacteria and a amount of bacterial biomass both in the leachate, and in the subsoil after leaching incubation were studied. The leachate from soil columns was collected every 3 d during the 30-d incubation period. The soil columns were packed with plow layer soil samples with and without rice straw (RS) amendment, and the subsoil column was connected to the plow layer soil column without RS. Numbers of total bacteria, culturable aerobic bacteria, and a amount of bacterial biomass in the leachate decreased with the incubation time. There was no correlation between the number of total bacteria in the leachate and the concentration of total organic carbon in the leachate. Bacteria less than 0.1 µsm³ in size predominated in the leachate, especially in that from the plow layer soil column with RS. Percentages of the number of Gram-positive bacteria in the leachate were very low (less than 7% of the total bacterial number), while the percentage in the subsoil after the leaching experiment was in the range of 21–82%. The sum of the number of bacteria percolated from the plow layer soil column with RS during the 30-d period of incubation and the sum of the amount of biomass C were 39 and 77% less than the corresponding values for the bacteria percolated from the plow layer soil column without RS. Percentages of culturable aerobic bacteria among the total bacteria ranged between 2.8 and 37% in the leachate, while less than 0.6% in the subsoil after the leaching experiment.     

Investigation of Associations Between Rhizosphere Microorganisms and the Chemical Composition of Flue-Cured Tobacco Leaves Using Canonical Correlation Analysis

Canonical correlation analysis was applied to determine the relationship of rhizosphere microorganisms to common chemical components in flue-cured tobacco leaves. The results were as follows: (1) The chemical composition of the tobacco was related to the major microbial physiological groups in the rhizosphere soil. No close relationship was found with the populations of bacteria, fungi, and actinomycetes. (2) Greater contents of total nitrogen and potassium in tobacco leaves were associated with larger populations of aerobic nitrogen-fixing bacteria and with smaller populations of aerobic cellulose-decomposing bacteria. In addition, potassium content was also negatively correlated with nitrosobacteria counts but showed no close relationship with the potassium bacteria in the rhizosphere. The nicotine content was associated with greater populations of nitrosobacteria and nitrobacteria, and the content of water-soluble total sugar was positively correlated with the counts of nitrosobacteria.     

Dry rehydratable films for enumeration of coliforms and aerobic bacteria in dairy products: collaborative study

A collaborative study was conducted to compare proposed dry-film plating methods, using aerobic count plates and coliform count plates, to standard agar plating methods for quantifying aerobic bacteria and coliforms in dairy products. In this study, 5 food products (chocolate milk, pasteurized cheese, nonfat dry milk, evaporated milk, and vanilla ice cream), selected as representative dairy products, were analyzed by 11 collaborating laboratories. The results indicate that the dry-film plating methods are equivalent to or better than the agar plating methods. The aerobic count and coliform count dry-film plating methods have been adopted official first action.     

Defined substrate technology method for rapid and specific simultaneous enumeration of total coliforms and Escherichia coli from water: collaborative study

The defined substrate technology (DST) method is a reagent system designed to enumerate specific target microbes(s) from a mixture of bacteria. The system simultaneously enumerates total coliforms and Escherichia coli directly from a water sample. The reagent contains o-nitrophenyl-beta-D-galactopyranoside (ONPG), which is hydrolyzed by total coliforms to produce a yellow chromogen, and 4-methylumbeilliferyl-beta-D-glucuronide (MUG), which is hydrolyzed and fluoresces when E. coli organisms grow. Noncoliform bacteria are suppressed and cannot metabolize the indicator nutrients. Nine laboratories participated in a field evaluation of the method, which covered a wide range of surface and subsurface water sources and water-processing modalities, including the examination of natural samples. The DST system was compared to multiple-tube fermentation (MTF) (quantitative) and presence-absence (P-A) (qualitative) Standard Methods formats. Comparison of water samples from natural sources by using the most probable number (MPN) procedure showed that the DST test was equivalent to the currently used MTF test. Results from the DST and the qualitative P-A procedure showed that these tests agreed with each other in 94% of the water samples analyzed. Specificity of the DST method was established by subculturing a species consistent with a total coliform or E. coli from each positive tube. Eight laboratories participated in a collaborative study of the method. Each laboratory received 3 concentrations of E. coli (organisms/100 mL); 10 (low); 60 (medium); and 120 (high). The DST test was inoculated from a split sample of each bacterial density in parallel with Standard Methods brilliant green lactose broth.(ABSTRACT TRUNCATED AT 250 WORDS)