Relevant factors affecting microbial surface decontamination by pulsed light

Pulsed Light (PL) uses intense flashes of white light rich in ultraviolet (UV) light for decontamination. A log-reduction higher than 5 was obtained in one flash and at fluences lower than 1.8 J/cm² on spores of a range of spore-forming bacteria, of vegetative cells of non-spore-forming bacteria and on yeasts spread on agar media. Vegetative cells were more sensitive than spores. The inactivation by PL of Bacillus subtilis, B. atrophaeus, B. cereus, Geobacillus stearothermophilus, and Aspergillus niger spores sprayed on polystyrene was similar. The inactivation by PL of B. subtilis and A. niger spores sprayed on glass was slightly lower than on polystyrene. No alteration of the spore structures was detected by scanning electron microscopy for both PL treated B. subtilis and A. niger spores. The inactivation of spores of B. subtilis, B. atrophaeus, B. cereus and B. pumilus by PL or by continuous UV-C at identical fluences was not different, and was much higher by PL for A. niger spores. The increase in the input voltage of the lamps (which also increases the UV-C %) resulted in a higher inactivation. There was no correlation between the resistance to heat and the resistance to PL. The relative effect of UV-C radiations and light thermal energy on PL inactivation was discussed.     

影响苹果香气成分和生物合成因素研究概述

概述了常见六种苹果品种的主要香气组分,介绍了苹果香气的主要合成途径以及影响香气合成和释放的主要因素。酯类物质是苹果香气的主要成分,占据78%～92%的组分,其次为醇类,占有6%～16%的成分。苹果品种、生长环境、产地、采收时期、贮藏条件和时间等因素是影响苹果香气的主要因素。     

Investigation of factors affecting voluntary and involuntary culling in expanding dairy herds in Wisconsin using survival analysis

Trends in the relative risk of voluntary culling of low-producing cows and involuntary culling of high-producing cows were examined in 186 Wisconsin dairy herds that expanded significantly between 1994 and 1998. A Weibull model for survival analysis was applied to data of 72,456 Holstein cows with first calving from 1981 to 2000; this model included a time-independent effect of age at first calving and time-dependent effects of year-season, age-parity, and within herd-year quintile for combined fat + protein yield (by time period). The relative risk of (involuntary) culling of high-producing cows (versus average cows) increased from 0.5 in 1981 to 1989 to 0.68 in 1996 to 2000. Meanwhile, the relative risk of (voluntary) culling of low-producing cows decreased from 4.20 to 2.55 over the same time period. Variables related to facilities, labor, and management were obtained via survey, and the relative risk of culling for high-and low-producing cows after expansion (1996 to 2000) was calculated for different levels of each variable. Herds with fewer cows per employee and a greater percentage of labor supplied by family members tended to have lower risk of involuntary culling of profitable cows. Likewise, high-producing cows in herds with fans, sprinklers, self-locking manger stalls, palpation rails, and maternity pens had a significantly lower risk of culling than cows in herds without such facilities. Herds that used 100% artificial insemination (AI) had lower risk of involuntary culling than non-AI herds or herds with a cleanup bull, but 3x milking and use of a custom heifer grower led to unfavorable trends in involuntary culling. In summary, this study documented the unfavorable trends in voluntary and involuntary culling in expanding herds and quantified the gains producers can expect in cow survival by investing in improvements in facilities, labor, and management.     

Stimulation of microbial urea hydrolysis in groundwater to enhance calcite precipitation

Addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. Generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single-well experiment, dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased 1-2 orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from < 0.1 to > 25 nmol L(-1) hr(-1). A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 d(-1). Although collateral impacts such as reduced permeability were observed, overall results indicated the viability of manipulating biogeochemical processes to promote contaminant sequestration.     

Wooden boards affecting the survival of bacteria?

Escherichia coli pIE639 and Enterococcus faecium as hygienically relevant test bacteria. The development of the bacterial titer was evaluated by culturing on agar contact plates and investigating wood shavings. Survival of the test bacteria depended on different factors such as tree species, the initial inoculum size and the characteristics of the inoculated strain. The bacterial titer decreased fastest on pine compared to other woods (spruce, beech, poplar) and plastic. After bacterial infestation only pine wood was germ-free at the surface and in the inner structure after a few hours. The survival of the bacteria on poplar and beech was comparable to their survival on plastic. The study indicated that an antibacterial effect of wood, especially for pine, is caused by the hygroscopic properties of wood and the wood extractives. The antibacterial effect of pine wood was not influenced by the storage time of the wood following harvest or the functional condition of the wood up to a germ load of 10⁸ CFU/cm² E. coli pIE639.

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Escherichia coli pIE639 und Enterococcus faecium als hygienisch relevante Testbakterien beimpft. Die Entwicklung des Bakterientiters ist durch Abklatschproben und Untersuchung von Hobelsp?nen verfolgt worden. Das überleben der Testbakterien war dabei von verschiedenen Faktoren abh?ngig, wie z.B. von der Holzart, der Animpfdichte und der Art des inokulierten Bakterienstamms. Der Bakterientiter nahm im Vergleich zu anderen Holzarten (Fichte, Buche, Pappel) und Kunststoff am schnellsten auf Kiefernholz ab. Nur Kiefernholz war innerhalb weniger Stunden an der Oberfl?che und im Innern des Holzes keimfrei. Das überleben der Bakterien auf Pappel- und Buchenholz war mit dem überleben der Bakterien auf Kunststoff vergleichbar. Die Studie deutet auf eine antibakterielle Wirkung von Holz hin, besonders von Kiefernholz, aufgrund der hygroskopen Eigenschaften von Holz und der Wirkung von Holzinhaltsstoffen. Die antibakterielle Wirkung von Kiefernholz wurde durch die Dauer der Lagerung nach der Holzernte und den Gebrauchszustand der Brettchen bis zu einer Keimbelastung von 10⁸ CFU/cm² E. coli pIE639 nicht beeinflusst.

     

Wooden boards affecting the survival of bacteria?

pIE639 and Enterococcus faecium as hygienically relevant test bacteria. The development of the bacterial titer was evaluated by culturing on agar contact plates and investigating wood shavings. Survival of the test bacteria depended on different factors such as tree species, the initial inoculum size and the characteristics of the inoculated strain. The bacterial titer decreased fastest on pine compared to other woods (spruce, beech, poplar) and plastic. After bacterial infestation only pine wood was germ-free at the surface and in the inner structure after a few hours. The survival of the bacteria on poplar and beech was comparable to their survival on plastic. The study indicated that an antibacterial effect of wood, especially for pine, is caused by the hygroscopic properties of wood and the wood extractives. The antibacterial effect of pine wood was not influenced by the storage time of the wood following harvest or the functional condition of the wood up to a germ load of 10⁸ CFU/cm² E. coli pIE639.     

Estimating microbial survival parameters from dynamic survival data using Microsoft Excel

Reliable survival parameter estimation is an essential part of building predictive models for microbial survival. It has been demonstrated that these parameters can be accurately identified using a one‐step regression approach that fits a survival model to multiple dynamic data sets at once. However, the existing methods are not quite user‐friendly because their application requires relatively high computer skills. In this study, a recursive equation for the Weibull model was used to construct microbial survival curves under dynamic conditions. Based on this, a procedure was developed to estimate survival parameters by fitting the equation to dynamic survival data sets using the built‐in functions and Solver of Microsoft Excel. The results showed that the method provided an easy and accurate way for estimating microbial survival parameters.     

Review on microbial degradation of aflatoxins

Aflatoxin (AF) contamination presents one of the most insidious challenges to combat, in food safety. Its adulteration of agricultural commodities presents an important safety concern as evident in the incidences of its health implication and economic losses reported widely. Due to the overarching challenges presented by the contamination of AFs in foods and feeds, there is an urgent need to evolve cost-effective and competent strategies to combat this menace. In our review, we tried to appraise the cost-effective methods for decontamination of AFs. We identified the missing links in adopting microbial degradation as a palliative to decontamination of AFs and its commercialization in food and feed industries. Cogent areas of further research were also highlighted in the review paper.     

Environmental factors affecting plasmin activity in milk

A total of 367 milk samples were collected from 43 individual Holstein cows during 1 yr. Samples were analyzed for plasmin activity, total casein, alpha s-casein (alpha s1-casein + alpha s2-casein), beta-casein, kappa-casein, and SCC. Least squares analyses showed that SCC in milk were positively related (r = .62) to plasmin activity. An increase of SCC from 100,000 to 1,300,000/ml was associated with a 2.3-fold increase in plasmin activity (100 vs. 230 x 10(-6) units/ml). Increased plasmin activity was associated with advancing stage of lactation and older cows after appropriate adjustments were made for the effects of milk yield and SCC. Milk samples obtained in fall and winter were higher, but not significantly, in plasmin activity. Plasmin activity was also associated with major casein components and milk pH. Correlations coefficients between plasmin and alpha s-casein, beta-casein, and pH were -.14, -.27, and .19.     

影响我国大豆价格变动的因素分析

近些年我国大豆价格变动比较显著,并且呈现不规则性,其原因是国内外的环境越来越趋于复杂化,经济形势日益严峻,行业间的竞争逐渐激烈,并且大多数加工企业过分地依赖进口大豆,导致目前国内对国产大豆供过于求。运用计量经济学和统计学的原理对影响大豆价格变动的因素进行分析和检验,结果显示玉米油价格和大豆消费量对大豆价格有显著影响,与大豆价格呈正相关关系。研究结果可为相关政策部门判断大豆价格的变化趋势和制定相关的政策提供依据。     

Calculating microbial survival parameters and predicting survival curves from non-isothermal inactivation data

Irrespective of whether the isothermal semi-logarithmic survival curves of heat inactivated microbial cells or spores are linear or nonlinear, it is theoretically possible to numerically calculate their survival parameters from inactivation data obtained under non-isothermal conditions. A method to do the calculation, when the temperature history ('profile') is expressed algebraically, is demonstrated with simulated survival curves. It has been tested with the published survival data of Salmonella, whose nonlinear semi-logarithmic isothermal survival curves can be described by a power law model. The reported survival ratios of Salmonella, determined during non-isothermal heat treatments in a broth and in ground chicken breast, were used to estimate its isothermal survival parameters in the two media and their temperature dependence. These, in turn, were used to predict the cells' survival curves under different temperature 'profiles.' There was a good agreement between the predicted and the reported experimental survival curves in the broth case and reasonable agreement in the ground chicken breasts, where the database was considerably smaller The development of a mathematical method to calculate survival parameters from non-isothermal inactivation data will eliminate the need to determine these parameters under isothermal conditions, which can only be approximated and are technically difficult to perform. In many cases, the proposed method will also enable the determination of the survival parameters in the actual food or medium of interest, which may contain particles, or is too viscous to be heated and cooled effectively using the currently available experimental procedures. In principle, the described mathematical method can also be used to assess organisms' survival parameters in nonthermal inactivation processes, such as exposure to a dissipating chemical agent or the application of ultra high-pressure.     

Cognitive factors affecting taste intensity judgments

The mean sensory response is often considered to represent the perceived intensity for a stimulus on the specified attribute. However, a momentary judgment is the outcome of a number of physical, physiological, and psychological processes. Four types of cognitive variables are discussed, that can affect the outcomes of an intensity scaling experiment.

First of all, the role of cognitive algebra and concept formation in tasks varying with regard to the number of stimuli to be compared, and with regard to the type and number of response scales used, is discussed. Subsequently, the effects of stimulus set characteristics on context and sequence effects are reviewed. Thirdly, temporal changes in responses during the time course of an experimental session are related to fatiguing and learning. Finally, the role of subjects' expectations is discussed.     

论影响腐乳前期培菌的主要因素

腐乳生产按生产工段可分为前期培菌和后期发酵。影响腐乳前期培菌的主要因素有白坯含水量、菌种质量、操作及卫生管理等。该文分别对其重要性、操作要点、检验方法等作了详细说明。     

文胸结构设计及其影响因素

文胸是对合体性要求很高的女性内衣,对文胸结构设计方法的研究有助于提高文胸的功能性和舒适性。本文通过从文胸基础样版、文胸部件结构设计和文胸结构设计的影响因素三个方面的国内外文胸结构设计文献综述,分析了文胸结构设计方法的现状及不足;探讨了文胸结构设计的两个影响因素;进而提出文胸结构设计的发展趋势。这些研究结果将为文胸结构设计方法的进一步发展提供一定的依据和帮助。     

微生物对葡萄酒香气的影响综述

香气是葡萄酒的重要感官质量指标之一,葡萄酒的酿造过程其本质是酵母菌、乳酸菌等微生物代谢活动的过程,使葡萄酒产品的香气表现得复杂和多样性.综述了酿酒酵母、非酿酒酵母、乳酸菌及霉菌在葡萄酒酿造过程中的作用,分析了酿酒微生物糖苷酶在酿酒过程中促进葡萄酒香气糖苷水解释放的研究进展.最后,就酿酒微生物应用于葡萄酒酿造,改善葡萄酒风味特征的研究重点和研究手段作了展望.     

乳蛋白质加工过程中影响因素的探讨

介绍了蛋白质是乳中最重要的营养成分,牛乳中蛋白质含量为3．3％左右。阐述了牛乳的加热、原料乳的酸度、异常乳、均质处理及微生物对乳蛋白质的影响。在加工过程中,通过采取相应的措施使牛乳蛋白不受破坏并保持优良的品质,从而在人体内得到高效率吸收。     

论影响腐乳出坯率的主要因素

提出了造成腐乳坯(又称白坯)出坯率低的主要原因是大豆中蛋白质在不同操作工序中流失,如泡豆时间过长随泡豆水流失,豆浆出率太多使豆浆浓度过稀随黄泔水流失,泡豆容器设定不合理,太小使豆泡不透形成夹生豆,及缺少复磨工序使蛋白质留存豆渣中,容器凝固剂浓度高、点浆过速使蛋白质分子过度收缩形成豆脑组织保不住水,从而使蛋白质随黄泔水流失。就如何提高原料蛋白质利用率及白坯出坯率提出了参考意见。     

Some factors affecting amylolytic behaviour in Irish flours

Examination of a large number of samples from the 1967 Irish wheat crop indicated departures from the normal relationship between α-amylase activity as determined by dextrinogenic and by viscometric methods. Comparison of falling numbers and amylograph maxima indicated that these two methods could not be used as equivalent alternatives for the prediction of a-amylase behaviour. Studies on a series of flour samples covering a wide range of amylase activities showed that differences between the autolytic methods examined were associated with starch properties. Gelling properties at maximum temperatures were found to influence amylograph maxima while susceptibility of the starch to enzyme attack in the early gelatinisation stages was responsible for differences in falling numbers. There was close association between starch pasting viscosities and susceptibility to mechanical damage during milling.     

酒精发酵过程中影响红葡萄酒颜色的五大因素

葡萄酒按颜色可划分为白葡萄酒、桃红葡萄酒和红葡萄酒。红葡萄酒颜色几乎包括了所有的红色,主要有宝石红、鲜红、深红、暗红、紫红、黄红、棕红、瓦红、砖红等。新红葡萄酒的颜色多呈紫红、鲜红、宝石红,伴随着葡萄酒的成熟,单宁与游离花色等结合,使酒体渐显黄色调,所以陈年红葡萄酒多为瓦红、砖红、棕红等颜色。近年来随着葡萄酒在中国的兴起,中国葡萄酒生产企业纷纷引进国外先进酿酒设备,采用先进的酿造工艺,所生产出葡萄酒的质量较以前有了极大幅度的提高,但国内葡萄酒多存在一种现象,就是红葡萄酒颜色偏浅,尤其是与进口红葡…