微波杀菌动力学及其影响因素的研究

本实验研究了不同温度条件下微波杀菌动力学D值;并且就食品体系中相应的pH和盐浓度对微波杀菌效果的影响作了探讨;同时对微波杀菌的机理进行了初步的研究。结果表明,相同温度下,微波功率越大,细菌的致死率越高;相同功率下,设定微波温度越高,其D值越小;当pH低于最适生长温度时,细菌对微波的敏感性增加,致死率提高;金黄色葡萄球菌(60℃)在20g/L的NaCl溶液中的致死率最大,而大肠杆菌(55℃)致死率随NaCl浓度增加而降低。微波处理后的金黄色葡萄球菌,经Flou-3/AM作用,其荧光值随温度的升高而增加,说明微波致金黄色葡萄球菌死亡的原因主要是改变了细胞膜的通透性。     

微波加热对大肠杆菌与金黄色葡萄球菌蛋白质与核酸变性的影响

研究微波杀菌过程中蛋白质与核酸的变性程度及其与微生物致死率之间的关系,测定了微波加热过程中大肠杆菌与金黄色葡萄球菌的蛋白质与核酸的“内源荧光”及残存菌数的变化。试验结果表明,当温度升高至50,55℃,大肠杆菌与金黄色葡萄球菌蛋白质和核酸“内源荧光”强度以及致死率均米发生明显变化;当温度升高至60℃时,大肠杆菌胞内蛋白质和核酸的“内源荧光”强度以及致死率分别增加了44．4％,41．8％,33％,而此时,金黄色葡萄球菌分别增加了8．7％,9．0％,12％;当温度升高至65℃时,大肠杆菌增加程度分别为71．3％,70．2％,65％,金黄色葡萄球菌变化程度分别为9．0％,10．6％,23％。随着微波加热温度的升高,大肠杆菌与金黄色葡萄球菌的蛋白质与核酸的“内源荧光”强度变化且与致死率呈正相关,因此,胞内蛋白质与核酸变性是微生物微波致死的因素之一。     

姜黄素介导的光动力技术对鲜切马铃薯的杀菌效果

本文运用光动力技术（Photodynamic technology,PDT）对鲜切马铃薯进行非热杀菌,实验选用姜黄素为光敏剂,420 nm LED蓝光为激发光源。探究了光照功率、光照时间、孵育时间以及光敏剂浓度等因素对鲜切马铃薯表面大肠杆菌、金黄色葡萄球菌杀菌效果的影响,并确定最优杀菌条件。结果表明,该技术对大肠杆菌的最优杀菌条件分别为:光照功率40 W、光照时间20 min、孵育时间15 min、姜黄素浓度30 μmol/L;金黄色葡萄球菌的最佳杀菌条件分别为:光照功率40 W、光照时间10 min、孵育时间15 min、姜素浓度30 μmol/L。与对照组相比,光动力技术处理后的大肠杆菌与金黄色葡萄球菌菌落总数分别为降低3.60与5.23 lg CFU/mL。     

脉冲磁场对大肠杆菌和金黄色葡萄球菌杀灭效果的验研究

通过试验,考察了脉冲磁场对于大肠杆菌和金黄色葡萄球菌杀灭效果的影响.试验结果表明,脉冲数(杀菌时间)和磁场强度对两株菌的杀菌效果影响显著,脉冲数增至20以后,杀菌效果趋于稳定;脉冲数对杀菌效果的影响大于磁场强度.     

氯化钠对几种常见菌的抑制作用

文章主要研究了NaCl对几种常见菌的抑制作用,设计了梯度平板实验和肉汤增值实验.梯度平板实验表明:很低的NaCl浓度就能抑制假丝酵母和乳酸杆菌生长;NaCl溶液浓度大约在5%以下对大肠杆菌具有抑制作用;浓度大约为8.5%的NaCl溶液对金黄色葡萄球菌具有抑制作用.肉汤增值实验表明:浓度4%的NaCl溶液对大肠杆菌具有抑制作用,浓度1.5%的NaCl溶液对乳酸杆菌和假丝酵母具有明显抑制杀灭作用,浓度7.5%的NaCl溶液对枯草芽孢杆菌具有抑制作用,浓度10%的NaCl溶液对金黄色葡萄球菌具有抑制作用.实验结果为NaCl抑菌作用提供了数据支持,所设计的实验方法为进一步开展NaCl杀菌抑菌作用的研究奠定了基础.     

超声处理对羊乳中大肠杆菌和金黄色葡萄球菌的杀灭效果

以新鲜羊乳为原料,研究了超声处理对新鲜羊乳中大肠杆菌和金黄色葡萄球菌的杀菌效果,为羊乳的非热杀菌方法及产品开发提供参考。基于单因素实验,采用Box-Behnken试验设计研究了超声功率、温度及时间对羊乳中大肠杆菌和金黄色葡萄球菌杀菌效果的影响,并以大肠杆菌和金黄色葡萄球菌的灭菌对数值为响应值,通过响应面分析对超声处理条件进行了优化,并研究了超声处理和巴氏杀菌处理对两种菌株菌体的破坏情况以及贮藏期内菌落数的变化。结果表明,超声处理羊乳的最佳条件为超声功率530 W,超声温度60 ℃,超声时间30 min,在此条件下对大肠杆菌和金黄色葡萄球菌的灭菌对数值可到达7.55和6.53。与巴氏杀菌处理相比,超声处理能更大程度地破坏菌体细胞表面结构,杀菌效果更好,并能将羊乳贮藏期从巴氏杀菌处理后的14 d延长至21 d,品质要求仍符合国家标准。     

利用程序模拟水浴升温比较微波加热与水浴杀菌的D值和Z值

通过程序控制改变微波炉的加热方式，使微波加热升温方式与水浴加热方式相近。利用此方法．分别测定了三种食源性致病菌，大肠杆菌（Escherichia coli）、乙型副伤寒沙门菌（Salmonella paratyphi B）在50.55.60℃水浴和微波加热杀菌的D值，以及金黄色葡萄球菌（Staphylococcus aureus）在55，60，65℃水浴和微波加热杀菌的D值。通过比较相同温度条件下大肠杆菌、沙门氏菌和金黄色葡萄球菌微波和水浴杀菌D值与Z值，可以发现微波杀灭的效果与水浴杀菌相近，未发现显著的微波非热效应。     

2450MHz频率微波加热条件下番茄汁杀菌特性的研究

本研究选用番茄汁作为研究对象,使用频率为2450MHz的微波进行加热,以时间、功率以及样品的含糖、含盐浓度作为参数,考察样品的升温模式、杀菌效果以及番茄汁的品质指标.本研究中,热效应为微波致死微生物的主要原因.添加糖和盐的样品,经微波处理后,微生物的致死率发生显著变化.微波处理后的样品,L*(亮度)增加,a*(红度)下降,番茄红素测得值增加,较传统巴氏杀菌更好的保留了VC.     

脉冲磁场对大肠杆菌和金黄色葡萄球菌杀灭效果的试验研究

通过试验,考察了脉冲磁场对于大肠杆菌和金黄色葡萄球菌杀灭效果的影响。试验结果表明,脉冲数(杀菌时间)和磁场强度对两株菌的杀菌效果影响显著,脉冲数增至20以后,杀菌效果趋于稳定;脉冲数对杀菌效果的影响大于磁场强度。     

木棉花色素的微波提取及其抗菌作用

研究了木棉花红色素的微波提取工艺和木棉花色素乙醇提取液的抗菌性能。结果表明,木棉花色素微波提取的最佳工艺为微波功率750w、微波辐射时间90s、固液比1:60(W/V)。一定浓度的木棉花红色素对大肠杆菌、金黄色葡萄球菌、黑曲霉和酿酒酵母均有抑制作用,抑菌作用强弱的顺序为:金黄色葡萄球菌>酿酒酵母>大肠杆菌>黑曲霉。     

C. R. Henderson: the unfinished legacy.

Ideas and methods developed by Henderson have been applied widely to BLUP of additive genetic merit of animals and estimation of components of variance. However, a number of other contributions of Henderson to theory and application of animal breeding and statistics have not been as fully examined and exploited. Some of these contributions are complete in their own right and others lay the groundwork to help resolve remaining problems. Henderson had insight and made contributions to the areas of analysis of line and breed cross data, hypothesis testing under mixed linear models, prediction of breeding values with unknown variances, and selection models. The general flexibility of Henderson's mixed model methods to quantify a large variety of biological effects is also illustrated and discussed in light of new technologies in genetics and biology.     

C. R. Henderson: contributions to the dairy industry.

Through C. R. Henderson's position and the application of his knowledge, he had a major influence on genetic improvement in dairy cattle beginning in the 1950s. He developed herdmate comparisons in the United States. The first extensive program using pedigree selection and progeny testing of sires for use in AI was because of his suggestion. This program established the direction of dairy cattle improvement that still continues. He developed BLUP and discovered how to write the inverse of an additive genetic relationship matrix, A-1, without inverting the matrix. These accomplishments had a major impact on evaluation methods of dairy cattle and other livestock species. Use of BLUP and A-1 are standards for evaluation of breeding values all over the world. His pioneering work in estimation of components of variance and analyses of unbalanced data were also of primary importance for animal evaluation and many other applications. Henderson made a major contribution to mankind.     

Proteases of the soyabean. II. Specificity of the active fractions

Six proteolytic fractions of the soyabean differed in specificity on synthetic substrates. Their Michaelis constants on poly (L-glutamic acid) differed one from the other. The optimum pH values of proteolytic action were slightly lower than that of the crude extract. The fractions did not autolyse, nor did one fraction hydrolyse any other. Finally, none of the fractions exhibited trypsin-like activity, as characterised by ability to hydrolyse benzoylarginine ethyl ester, either at their optimum pH or at the pH optimum of trypsin.     

A modified hydroxamic acid method for the estimation of the activity of lipase (E.C. 3. 1. 1. 3)]

Optimal conditions for a modified hydroxymic acid method have been worked out with respect to the stability of the substrate emulsion; by systematically varying the ratios of the components of the solutions it was possible to develop a homogeneous reaction system which could be directly measured by spectrophotometry.     

美国引领在线葡萄酒消费

据OIV预计，世界葡萄酒消费量正缓慢增长，2005—2010年将上升8％。 但这种增长各地市场表现不一，葡萄酒品种间的增长也有差异。高端葡萄酒市场增长的较快，并且以卢森堡的人均消费增长的最快，美国市场也对这个增长起了很大作用。     

功能性红曲醋的研究

在进一步挖掘红曲保健功能的基础上,结合我国传统的保健调味品食醋,研制功能性红曲醋。在确定工艺路线后,首先进行醋酸菌的筛选工作,采用斜面分离纯化的方法得到所需的高纯度醋酸菌种子液,这其中历经两级种子的筛选方可将最终所得的醋酸菌接入发酵罐,得到所需产品。经检测,本产品呈棕红色,有光泽,具有发酵醋特有的香气,且无异味。醋液澄清无沉淀,其中酸度达4．9g／dL,还原糖2.30g／dL,盐分0．27g／dL,固形物11．88％。     

苔干水溶性粗多糖提取工艺及理化性质的研究

本文采用热水浸提、醇沉法提取苔干多糖,对苔干多糖提取工艺和一般理化性质进行了研究。选择浸提固液比、温度和时间作为单因素进行梯度实验,确定其条件范围,再通过正交实验L9(34)进一步确定苔干水溶性粗多糖最佳提取工艺条件。结果表明最佳提取工艺为:固液比1:40、浸提温度90℃、浸提时间3h、反复浸提2次。理化性质结果表明提取的苔干多糖中含有多肽或氨基酸,为蛋白质复合多糖。     

Jack-Bean Starch. 1. Properties of the Granules and of the Pastes

Jack bean (Canavalia ensiformis) starch is composed of granules measuring up to 37 micra. Gelatinization temperatures of the granules range from 67.5 to 78 °C. Its pastes, in concentrations up to 6 % did not show swelling peak which appears only in high concentrations. They are very stable during stirring, both at low and high temperatures. They are also more resistant to α-amylase bacterial action than those of corn starch. The results, both for granules and pastes of this starch, show a great resemblance with the same data for guandu bean.