ON THE DETERMINATION OF VOLATILE THIOLS IN BEER

The method of Ikeya for the determination of volatile thiols in beer by aspiration of these compounds into mercuric acetate has been examined. Cadmium acetate has been found to be unsuitable as an absorbant for removing hydrogen sulphide since it also combines with thiols. This reagent has been replaced by aqueous zinc acetate in a separate absorption trap. The proposed modification has the advantage of enabling estimations of hydrogen sulphide and of volatile thiols to be carried out on the same sample.     

浅谈企业利润计划完成程度计算方法

计划亏损企业的利润完成程度指标的计算是一个尚味算解决的 问题，有人增提出用功效和纱数法来测定 之，但功效系数法所作的测定与计划完成程度指标所作的测定其结果不不可比。     

Joint FAO/WHO Geneva consultation acute dietary intake methodology

Significant developments have been made at the international level in the methodology for conducting dietary risk assessments. The existing chronic exposure assessment methodology has been updated so that it takes account of the level of residues to which consumers are most likely to be exposed. In addition, short-term exposure assessment methodology has also been developed. This uses portion size data and takes account of the variability in residue levels between individual units where this is appropriate to the way the commodity is consumed. Other refinements to the assessment can also be made. Although the short-term methodology has been used successfully by a number of regulatory authorities, there is a need for data on portion sizes and typical unit weights before it can be fully implemented internationally.     

新型食品添加剂卡那霉素抗性基因编码蛋白的安全性评价

卡那霉素抗性基因是转基因植物中广泛使用的一类标志基因,近年来越来越多的转基因植物被批准商业化应用,由此衍生而来的含卡那霉素抗性基因及其编码产物的转基因食品也逐渐增多,因而其安全性受到普遍关注。FDA已批准卡那霉素抗性基因编码蛋白APH（3’）-Ⅱ可使为一类食品添加剂使用。本文对卡那霉素抗性基因的特性及其编码蛋白的安全性进行了综述评价。     

QVX型气动V形牵伸装置应用实践

对气动V型牵伸装置在产品质量、品种适应性能等方面进行了分析 ,对生产维护管理等方面进行了总结 ,结果表明 ,气动V型牵伸装置具有推广价值 .     

新型营养强化剂L-硒-甲基硒代半胱氨酸的研究进展

L-硒-甲基硒代半胱氨酸是一种天然含硒氨基酸,具有防治癌症、抗氧化、抗衰老、治疗心脑血管疾病、解重金属毒等作用,已于2009年被卫生部批准为新型营养强化剂.现代药理学研究表明不同形式的硒具有不同的抗癌效果,L-硒-甲基硒代半胱氨酸被证明是有效的化学抗癌剂之一.本文对L-硒-甲基硒代半胱氨酸的来源、抗癌作用机理、测定方法及其应用进行了综述.     

Control and reduction of free fatty acid concentration in oil recovered from fish silage prepared from sprat

Increases in the free fatty acid (FFA) content of oil recovered from sprat silage have been shown to be partially due to release of FFA from their water-soluble salts on acidification and to the carry over of certain organic acid acidulants. Acid hydrolysis has been shown to be a significant contributor to oil degradation at low pH, but a heat-labile catalyst active below pH 7.0 has been shown to be a contributor to FFA levels in the oil of sprat silage incubated for long periods of time. Preparation of silages using sulphuric-formic acid mixtures and the use of a preheat treatment have been shown to reduce this activity.     

MODELLING OF DIACETYL PRODUCTION DURING BEER FERMENTATION

Experimental brewing in stirred tanks has been carried out at different temperatures, pH's and agitation characteristics. A model based on biochemical pathways has been developed. The parameters have been evaluated to fit the results of diacetyl concentration evolution throughout fermentation. The resulting model has proved itself to be useful in predicting results in industrial cylindro-conical fermenters when delay due to non-agitation during the first few days is considered.     

Thermal protective performance of clothing exposed to radiant heat

Designing firefighter protective clothing requires many factors to be taken into consideration. Constructional parameters along with proper selection of materials are very critical and need to be extensively studied. In the present work, construction parameters of Kevlar woven and conex non-woven materials have been studied. Full factorial experiments have been conducted by varying factors like pick density of woven cloth and punch densities of non-woven fabric at three levels at three different heat fluxes. ANOVA has been done to analyse the significance of different factors and interaction between them. Time to cause second-degree burn injury has been found to be linearly related to pick and punch densities, where as it has non-linear relationship with variation in heat fluxes. Kevlar woven material with higher pick density combined with lower punch density produced maximum time before second-degree burn occurs.     

The separation of aliphatic amines in dilute aqueous solution by gas chromatography and application of this technique to the quantitative analysis of tri- and dimethylamine in fish

Gas chromatography on an alkaline Dowfax 9N9 column has been found to be suitable for the qualitative and quantitative analysis of alkylamines in dilute aqueous solution. The method has been applied to the analysis of trimethylamine (TMA) and dimethylamine (DMA) in fish and has been used to throw further light on uncertainties concerning the use of the “picrate” procedure for TMA determination.     

环线金刚石线锯机旋转切割的研究

对蓝宝石、晶体硅等贵重硬脆晶体加工的要求越来越高,如切割效率和表面加工质量,而且工件的尺寸也逐渐增大,需要设计一种高效的切割设备并探索新的切割方式。本研究建立了一种旋转切割模型,通过旋转工件进行切割,保持一种单点接触式的切割,提高环线金刚石线锯机的切割效率。利用自制的环形金刚石线锯机做切割实验,结果表明,相对于常规固定式的切割法,切割效率至少提高了50%,并且提高了表面加工质量。     

FURTHER STUDIES ON THE FOAM-STABILIZING SUBSTANCES IN BEER

A material containing both carbohydrate and protein together with some ferulic acid, and which has pronounced foam-stabilizing activity, has been isolated from beer. A fraction similar in constitution and activity to the beer constituent has been recovered from an aqueous extract of barley flour. These materials are comparable with a glycoprotein present in wheat flour; the latter has been shown to be effective in the stabilization of beer foam. There was little difference in the amount and activity of extracts prepared from different varieties of barley.     

Ultraviolet processing of liquid food: A review: Part 2: Effects on microorganisms and on food components and properties

The effectiveness of ultraviolet irradiation in inactivating microorganisms has been known for decades. Nevertheless, in the processing of foodstuff other important issues must be considered, such as organoleptic or nutritional properties preservation. Ultraviolet irradiation constitutes an alternative to thermal treatment that is being studied and developed to obtain a better final product sensory quality, but without neglecting microbial safety. Moreover, it has been proved that this technology can be useful to decompose some toxins that are not affected by thermal processing. In this piece of work, the effect of UV irradiation on all of these contaminants and components of liquid food has been reviewed.     

Effect of gauge length on loop strength of sewing threads

Seam strength prediction using loop strength has been found to be more accurate and has been consistently used by researchers over last few decades. But the testing gauge length for loop strength has not been standardized as in the case of thread tensile strength. In this paper, effect of gauge length on thread tensile strength and elongation in loop form and straight form has been studied. 40 tex and 60 tex mercerized cotton and spun polyester threads are used for the study. It is observed that there is no significant change in the loop strength of the threads as the gauge length increases, whereas the tensile strength of all threads decreases with the increase in gauge length. Elongation % is found to change significantly in both loop and straight form during tensile testing. Therefore, it is concluded that loop strength tests can be carried out at any gauge length unlike tensile testing of straight threads.     

CAMBRIDGE PRIZE LECTURE INDUSTRIAL SCALE RESEARCH INTO MALTING AND BREWING PROBLEMS*

A series of investigations into production processes is described. The interaction of grain and its environment during commercial barley steeping and germination has been examined. Deficiencies which may be induced by anaerobic conditions in steeping appear to be eliminated during germination. Conversely, malt quality may be affected by excessive steep aeration. In a study of commercial brewery fermentations the importance of wort production procedures in allowing an adequate supply of unsaturated fatty acids, essential for satisfactory attenuation, has been demonstrated. Differences in fermentation behaviour cannot be fully explained by the observed yeast sterol contents. Yeast glycogen does not appear to limit fermentation performance. The application of cross-flow membrane filtration (ultra- and microporous filtration) to the recovery of beer from conditioning tank residues has been examined. The pilot-scale production of high quality permeates, and the successful blending of permeate into finished beer, have been demonstrated. The economic advantages of the ultrafiltration process are assessed briefly.     

QUANTITATIVE ANALYSES OF BEER BITTERING SUBSTANCES AND HOP RESINS BY THIN-LAYER CHROMATOGRAPHY

A simple thin-layer chromatographic procedure for the quantitative analysis of beer bittering substances is described. In the beers examined, 88–100% of the Brenner determination can be attributed to isohumulones A and B and the ratios of these two isomers show a real variation. Alpha-acids have been shown to be present in our beers. Thin-layer chromatography has also been adapted for analysis of hop resins and with fresh hops excellent agreement has been obtained with the conductometric method of analysis.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE ESTIMATION OF FATTY SUBSTANCES IN CEREAL ADJUNCTS

A new method for the estimation of fatty substances has been tested. In this the ground sample is extracted successively with acetone and chloroform in the cold and the resulting non-volatile extract is weighed. The method has been found to be quicker and to give smaller errors both within and between laboratories than the method hitherto recommended and has accordingly been adopted as the recommended method of the Institute for fatty substances in cereal adjuncts.     

The role of antioxidant versus pro-oxidant effects of green tea polyphenols in cancer prevention

Consumption of green tea (Camellia sinensis) may provide protection against chronic diseases, including cancer. Green tea polyphenols are believed to be responsible for this cancer preventive effect, and the antioxidant activity of the green tea polyphenols has been implicated as a potential mechanism. This hypothesis has been difficult to study in vivo due to metabolism of these compounds and poor understanding of the redox environment in vivo. Green tea polyphenols can be direct antioxidants by scavenging reactive oxygen species or chelating transition metals as has been demonstrated in vitro. Alternatively, they may act indirectly by upregulating phase II antioxidant enzymes. Evidence of this latter effect has been observed in vivo, yet more work is required to determine under which conditions these mechanisms occur. Green tea polyphenols can also be potent pro-oxidants, both in vitro and in vivo, leading to the formation of hydrogen peroxide, the hydroxyl radical, and superoxide anion. The potential role of these pro-oxidant effects in the cancer preventive activity of green tea is not well understood. The evidence for not only the antioxidant, but also pro-oxidant, properties of green tea is discussed in the present review.     

THE SEPARATION AND IDENTIFICATION OF A DIMER OF CATECHIN OCCURRING IN BEER

A dimer of catechin has been separated from a number of ales, stouts and lagers. This compound has been shown to have the same structure as procyanidin B3, which has previously been isolated from plant sources. It can be conveniently synthesized from dihydroquercetin and catechin.     

面向大规模定制的电钻可拓配置设计的研究

在分析面向大规模定制设计的基础上,提出了面向大规模定制的可拓配置设计方法。本文将整个配置过程分解为可拓配置推理与可拓配置变换2个部分。其中,可拓推理解决配置设计的一般设计过程,找出与客户需求相匹配的产品单元;可拓配置变换解决配置设计过程中客户需求与现有产能的矛盾问题,通过查找不能满足客户需求的产品单元属性,发散出与这个属性相关的产品单元,再通过可拓学中的变换理论及方法,改变相应的产品单元,最终组合成客户满意的产品。本文以电钻为例,分析其成组机构,建立了电钻的产品主模型。在电钻产品物元模型上,应用可拓推理机制,提出了一套配置设计的设计算法,按照可拓变换的原理完成了对不符合要求的电钻部件的变换设计。