ARTIFACTS IN GLC DETERMINATION OF VOLATILE SULPHUR COMPOUNDS IN BEER

The chromatographic response of volatile sulphur components in the headspace of a typical Canadian ale investigated by a GLC technique using the FPD detector was found to vary according to the analytical procedure selected. Time and temperature of sample conditioning as well as mode of column preparation are stressed as the most important variables in the analysis of finished beer under atmospheres containing oxygen. It is recommended that caution be exercised in the identification by co-chromatography of volatile sulphur compounds in beer.     

DETERMINATION OF TOTAL CARBOHYDRATE IN BEER

A colorimetric procedure for the determination of total carbohydrate in beer has been evaluated in a collaborative trial. The method is recommended by the Analysis Committee.     

SUPEROXIDE DISMUTASE IN BARLEY

Superoxide dismutese occurs in barley where it can be measured using a xanthine oxidase assay, but not using an assay based on the reduction of Nitro Blue Tetrazolium by photo-reduced riboflavin. Three isozymes are present in the grain: two are cyanide-sensitive and one, of lower activity, is not. Superoxide dismutase is mainly in the embryo of barley and develops in the acrospire, rootlets and endosperm during germination. Synthesis of this enzyme is accelerated by exogenous gibberellic acid. Significant quantities of superoxide dismutase survive kilning: lager malts contain ca 50% more than do ale malts. The enzyme is rapidly destroyed during mashing at 65°C, but large amounts survive mashing at 45°C.     

ESTIMATION OF VOLATILE SULPHUR COMPOUNDS IN BEER

A method has been developed for the quantitative estimation of volatile sulphur compounds in beer at levels below 0.1 μg litre^?1. The method relies on the concentration of beer headspace volatiles onto a porous polymer followed by injection into a capillary gas chromatographic column using a thermal desorption cold trap injector. The volatile components are separated using temperature programming and detected by a flame photometric detector specific for sulphur compounds. The mean concentrations and the estimates of r₉₅ (μg litre^?1) for volatile sulphur compounds measured in a commercial lager were respectively: methanethiol (0.33, 0.30); dimethyl sulphide (19.3, 5.3); carbon disulphide (0.42, 0.32); ethylene sulphide (0.37, 0.05); 1-propanethiol (0.11, 0.02); methyl thioacetate (11.7; 2.7); methyl disulphide (0.34, 0.42). The method is a significant improvement over previous techniques for the quantification of sulphur-containing volatiles in beer .     

日本食品安全对策与检测技术进展

食品安全是食品必备的基本要素。日本近年来高度重视食品安全问题，采取了一系列对策。概述了日本近年来有关食品安全对策及其检测技术的进展情况。     

砂糖桔营养成分分析

对砂糖桔的常规营养成分、矿质元素及Vc进行了分析测定,并与芦柑、脐橙两种柑桔进行了对比研究。结果表明,砂糖桔的营养成分与其它两个品种的柑桔相差不大,其中总糖含量高达13.06%,粗纤维、Vc和矿质元素含量丰富,矿质元素中Fe、K、Zn、Cu的含量相对而言较高。该研究为砂糖桔的大面积栽植、加工与利用提供科学依据。     

THE DETERMINATION OF SULPHUR DIOXIDE IN MALT

The Institute of Brewing Recommended Method for the determination of sulphur dioxide in beer has been modified for determination in malt. Three inter-laboratory trials are reported and the resulting procedure is described. It has the advantages of being well tried in its general form and employing relatively cheap equipment. While the inter-laboratory reproducibility achieved was not particularly good the method is published for use in laboratories where it may fulfil a present need.     

A SEMI-AUTOMATIC METHOD FOR THE GAS CHROMATOGRAPHIC DETERMINATION OF VICINAL DIKETONES IN ALCOHOLIC BEVERAGES

A method has been developed for the routine determination of diacetyl and pentanedione in alcoholic beverages. After the addition of internal standard and any necessary dilution, a stream of nitrogen swept the components of the sample at a fixed temperature to a 2 ml injection loop of a gas chromatograph fitted with an electron capture detector. The data from the chromatograph were collected on cassette and processed by computer. The time between starting temperature equilibration of the sample and obtaining the diketone content as μg/litre beverage was about 17 min. The coefficient of variation for diacetyl was 1·8% (5·1%, with manual injections) and for 2,3 pentanedione 1·6% (9·1%) for replicated analyses of the same sample.     

线性回归中的影响度量

考察了一次剔除一组或多组数据对某些点处拟合值的影响问题，得到了影响度量的广义类．它包含了Ｃｏｏｋ距离、ＷｅｌｓｃｈＫｕｈ统计量、ＡＰ统计量等     

GAS CHROMATOGRAPHIC DETERMINATION OF TRIHYDROXYOCTADECENOIC ACIDS IN BEER

A rapid and quantitative method for measuring the content of trihydroxyoctadecenoic acids in beer is described. The acids are extracted from degassed beer with ethyl acetate and methylated with diazomethane. After washing, the methylated compounds are silylated and analysed by gas chromatography. The coefficient of variation of the method is 3·2%. The amounts of total trihydroxyoctadecenoic acids in commercial beer samples varied from 4 to 12 mg/litre. The effects of these acids on beer flavour and head retention are discussed.     

柿子霜成份检测分析

经分析柿子霜中含有甾体、三萜、脂肪油、有机酸、糖类等成分，其含糖量较高，含多糖量为8．50mg／g。用高效液相色谱仪进一步检测出糖成分中舍葡萄糖；50．566％；果糖；13．25％；蔗糖0．923％；微量甘露糖和木糖；不合寡糖。     

PERCEPTION OF HETEROCYCLIC NITROGEN COMPOUNDS IN MATURE WHISKY

Standard solutions of N-heterocyclic compounds in ethanol are extracted with pentane at a range of pHs. Pentane extractions are also performed on N-heterocyclic standards in ethanol with addition of Limousin Oak extract at a range of concentrations. The effects observed on extraction are collated with sensory assessments. The results obtained would suggest that pyridines are absent from the aroma of a mature whisky due to its acidity, and that interaction with wood constituents in the cask does not occur.     

聚丙烯酸酯涂料粘合剂中未反应单体的测定

介绍了聚丙烯酸酯涂料印花粘合剂中未反应单体的测定方法。该方法通过加入四氯化碳,使测定过程中产生的絮状物得以改善,从而增加了分析结果的准确性。     

APPROACHES TO RAPID MICROBIAL MONITORING IN BREWING

Current practices in microbial monitoring in brewing rely heavily on conventional plate counts and forcing tests. Such tests, which require a sufficient time for microbial growth, provide a historical record, but are of limited use in process control. A primary need is for rapid and sensitive procedures which detect viable organisms. The means to distinguish organisms which can spoil from those which are benign, and the automation of procedures, are secondary considerations. Evaluating available methods for rapid microbial monitoring in the context of brewing industry requirements has identified areas for further development.     

VARIETAL DEPENDENCE OF HOP FLAVOUR VOLATILES IN LAGER

A series of lagers brewed with single hop varieties was analysed via extraction and gas chromatography/mass spectrometry. Each hop variety contributed a small number of unique flavour compounds to the beers. Significant, reproducible differences were found between the concentrations of individual hop compounds and hop compound classes in the different beers.     

对我国超硬材料行业的环境分析

本文对超硬材料行业作了从规模到市场变化；从企业内部条件条件到企业生产经营活动的现实分析。说明在加入WTO的新形势下，正确分析超硬材料行业内外部环境，是企业制定经营战略的首要任务。     

动物性食品中氯霉素残留的定量分析研究

氯霉素由于存在严重毒副作用，已被许多国家和地区列为禁用药物。动物性食品中氯霉素残留检测方法的检出限已成为国际贸易合作中新的技术性壁垒。本文重点综述了高效液相色谱法和气相色谱法等定量方法来分析检测动物性食品中氯霉素的残留含量。     

AN AUTOMATIC ANALYSIS OF NITROGEN IN WORT

An automatic analysis which is based on the spectrophotometric method, is described for the determination of nitrogen in unhopped wort. Wort was diluted to about 100-fold and the extinction at 213 nm was measured with an auto analyser. Nitrogen content in wort was calculated from the comparison with the extinction of several standard solutions. This automatic method is simple and rapid, and the data obtained with this method were closely correlated with those obtained with the classic Kjeldahl method (r = 0·895). The results obtained suggest that this method is practical for the analysis of many small scale samples in barley breeding.†     

食品中有机磷农药检测方法研究进展

有机磷农药作为一类高效、广谱的杀虫剂、除草剂等正被广泛地用于农业生产中。但其大量使用后对人、动物和环境产生的危害也日益严重。由于近些年来食品安全问题已经引起了越来越多人的关注，对食品中有机磷农药残留的检测研究已经引起了包括我国在内的世界各国的重视。在总结前人工作的基础上对食品中有机磷农药常用的检测方法做一综述。     

COMPARISON STUDY OF EGG YOLKS AND EGG ALTERNATIVES IN FRENCH VANILLA ICE CREAM

Egg alternatives may replace egg as a functional ingredient in French vanilla ice cream due to their functional and dietary benefits. These egg alternative ingredients include modified corn starch (MCS), whey protein concentrate (WPC) and soy protein isolate (SPI). The objective of this study was to compare the physical and sensory properties of several commercially available egg alternatives in a vanilla ice cream formulation. The SPI exhibited a significantly lower L value compared with the other egg alternatives, whereas the control exhibited a significantly higher b value compared with the other treatments. The apparent viscosity value of MCS was approximately 10-fold greater than the other egg alternatives. There were no significant differences in appearance and mouth-feel among the control, MCS or WPC treatments, whereas SPI exhibited a significantly lower mouth-feel score compared with the other treatments. The control exhibited significantly higher flavor and acceptability scores compared with the other egg alternatives, whereas SPI treatment exhibited least desirable flavor and acceptability. Consumer panelists would purchase the control with the egg alternative formulations.

PRACTICAL APPLICATIONS

The egg alternatives were used to replace egg as a functional ingredient in French vanilla ice cream production. These alternatives can deliver functionality at a lower cost and can be incorporated to produce a suitable ice cream.