ESTER CONTROL IN HIGH GRAVITY BREWING

Pilot brewing trials have shown that beers of good flavour can be produced using a high gravity brewing system in which worts of 1080° gravity are fermented and the resulting beers diluted to give an O.G. of 1040°. The flavour can differ from that of the control beers in that the diluted beers retain more ester and strong ale character. Trials have been carried out to study possible methods for control of ester production to permit product matching. A promising approach is controlled contact with oxygen during fermentation.     

CAMBRIDGE PRIZE LECTURE DIMETHYL SULPHIDE—ITS ORIGIN AND CONTROL IN BREWING

The fate of dimethyl sulphide (DMS) and its precursors, S-methylmethionine (SMM) and dimethyl sulphoxide (DMSO), in the malting and brewing processes, has been studied on both a laboratory and a production scale. The information gained has been used to show how the level of DMS in beer may be controlled. The principal determinant of the beer DMS level was the SMM present in malt. DMSO was not a significant precursor of DMS in normal lager production.     

阿魏酸酯酶的研究与应用

阿魏酸酯酶指能水解阿魏酸甲酯、低聚糖阿魏酸酯和多糖阿魏酸酯中的酯键,将阿魏酸游离出来的一种酶.它能切断细胞壁中多糖-多糖、多糖-木质素间的交联,有利于细胞壁物质中多糖的降解和木质素的释放,因此在食品、饲料和造纸工业具有广阔的应用前景.本文介绍了阿魏酸酯酶的结构特征、酶学特性、产酶微生物及其在食品、饲料和造纸工业中应用的前景.     

复合酶水解玉米皮制备阿魏酸和低聚糖的研究

研究采用阿魏酸酯酶、阿拉伯木聚糖酶、纤维素酶和Viscozyme L（戊聚糖复合酶）共同作用于去淀粉玉米皮，制备阿魏酸和低聚糖。结果表明，当混合酶制剂（阿魏酸酯酶和阿拉伯木聚糖酶）的添加量与底物干重比为6：1、纤维素酶和Viscozyme L的添加量均为底物干重的5％时，在pH5．5，45℃下酶解24h，能得到最高的阿魏酸和低聚糖产量；在此条件下能释放出去淀粉玉米皮中25．4％的阿魏酸和30．0％（以还原糖计）的低聚糖。     

THE MARGARET JONES MEMORIAL LECTURE AMINO ACIDS IN MALTING AND BREWING

Margaret Jones' researches into the role of amino acids in the biochemistry of malting and brewing are reviewed.     

THE DETERMINATION OF AMINO ACIDS IN WORT,BEER AND BREWING MATERIALS USING GAS CHROMATOGRAPHY

Various methods for the separation of amino acids from brewing materials and subsequent analysis by gas chromatography have been examined. Separation of the amino acids by ion exchange chromatography followed by derivatization and gas chromatography of the trifluoracetyl n-butyl or heptafluorobutyl iso-amyl esters proved the most satisfactory methods to employ.     

HORACE BROWN MEMORIAL LECTURE THE ROLE OF NITROGEN IN BREWING

The development of chromatographic methods of analysis in the 1940's and 1950's allowed detailed investigations to be made into the role of nitrogenous compounds in malting and brewing. The development of individual amino acids during malting, their extraction in the brewhouse and assimilation by culture yeasts during fermentation are reviewed as are their effect on the quality of the final beer.     

阿魏酸及其衍生物对食用油脂抗氧化效果的评价

对阿魏酸及其衍生物在食用油脂中的抗氧化效果进行评价。通过考察油脂过氧化值（POV值）与酸价（AV）这两个指标，分别对BHT（二丁基羟基甲醚）、阿魏酸、阿魏酸乙酯、阿魏酸戊酯、α-生育酚阿魏酸酯在植物油脂（大豆油）与动物油脂（猪油）当中的抗氧化性能进行比较与评价。     

NEW ANALYSES IN MALTING AND BREWING*

Recent advances in our knowledge of the plant physiological and biochemical processes surrounding malting and brewing have prompted the development of a new generation of analytical techniques. These techniques are based upon the measurement of biochemical and physical parameters which have lately been shown to directly influence the quality of both malt and beer. Recognition of these parameters, coupled with a deep insight of the physical and chemical changes that can occur during the entire malting and brewing production chain, allow strategic emplacement of new analyses in order to provide a superior specific monitoring of malting and brewing. In the present context we submit several examples of these novel analyses, spanning from barley control to analysis of pasteurising efficiency. Characteristic for all the analyses discussed, is the ease and rapidity with which they can be performed. The following methods are described: (1) Measurement of both pre-harvest sprouting and germination efficiency in barley. (2) Malt modification analysis to measure malting efficiency, time of kilning and malt homogeneity. (3) Rapid β-glucan analysis in malt, wort and beer. (4) Immunological analysis to determine the amount and type of additives in finished beer as well as addition of adjunct. (5) Enzymic and immunological control of beer pasteurisation.     

EXAMINATION OF SOME BREWING MATERIALS AND CARAMELS FOR THE POSSIBLE OCCURRENCE OF 4-METHYLIMIDAZOLE

An investigation was carried out to determine how much, if any, 4-methylimidazole is present in caramels and some other materials used in brewing. Existing analytical methods were modified to improve sensitivity. 4-Methylimidazole was not detectable in roasted barley, chocolate malt, crystal malt, Farbebier, wort and beer, when the limit of detection was 1 mg/kg. However, caramels manufactured by different processes contained amounts ranging from undetectable to 280 mg/kg.     

PHENOLIC ACIDS IN BEERS AND WORTS

The total contents of phenolic acids measured by high-performance liquid-chromatography were 5–8 mg/litre in beers brewed in Ireland whereas 16–40 mg/litre were present in four other beers. In all beers the predominant phenolic acids were vanillic, p-coumaric and ferulic acids. Free phenolic acids were extracted from Emma barley grains and malt in very small amounts (15–28 mg/kg) but larger quantities (191 mg/kg) were released on mashing the malt. Little change occurred in the contents of phenolic acids on processing a lager wort through to the finished beer. Treatment with excess Polyclar AT removed astringent flavour and phenolic acids from an experimental ale but this flavour loss could not be accounted for by the adsorption of phenolic acids. The flavour threshold for a nine-component phenolic acid mixture in lager was between 50 mg/litre and 100 mg/litre.     

INACTIVATION OF PAPAIN PROTEOLYTIC ACTIVITY IN THE PRESENCE OF ASCORBIC ACID AND CU++ IONS

The simultaneous presence of ascorbic acid, Cu⁺⁺ ions and oxygen causes reversible inactivation of proteolytic activity of papain. Low concentrations of ascorbic acid and Cu⁺⁺ ions have no effect on their own. Ascorbic acid at concentrations higher than 2 × 10⁻⁴ m inactivates papain irreversibly in the presence of Cu⁺⁺ ions. Papain inactivation is not accompanied by the destruction of papain molecules. Irreversible papain inactivation does not occur in solutions free of oxygen and the intermediates of ascorbic acid oxidation, i.e. dehydroascorbic acid and hydrogen peroxide, do not cause papain inactivation. The irreversible inactivation of papain is most probably due to free radicals formed during ascorbic acid oxidation. Owing to the possible occurrence of both ascorbic acid and Cu⁺⁺ ions in beer, partial irreversible inactivation of papain can be expected even at very low oxygen concentrations.     

DETERMINATION OF DNA AND OF OTHER NUCLEIC ACID FRACTIONS IN SACCHAROMYCES CEREVISIAE

After extraction overnight of Saccharomyces cerevisiae (baker's yeast) with dilute alkali, to remove nucleotide pools and RNA, acidification gave an insoluble residue from which DNA guanine and adenine were extracted, in the free form, by 1M perchloric acid at room temperature, and determined by cation-exchange chromatography. Percentage DNA in the yeast was computed as 0.062 × μmol/g of guanine + adenine. Preliminary extraction of nucleotides was unnecessary, and gave low results if acid reagents (perchloric or trichloroacetic acids) were used. Several reagents were tested for their ability to extract the nucleotide pool from intact yeast without significant effect on cell RNA content. The content of guanine + adenine in pool-free yeast was taken as giving the sum of RNA + DNA purines, RNA purines being found by difference.     

MEMORIAL TO MORITZ—THE INSTITUTE OF BREWING—ITS HISTORY,AIMS AND ACTIVITIES

The aims ideals and activities of the Institute of Brewing are reviewed from its inception in 1886 to the present day.     

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.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE DETERMINATION OF IRON AND COPPER IN BEER BY ATOMIC ABSORPTION SPECTROSCOPY

Methods for the determination of iron and copper in beer by atomic absorption spectroscopy are recommended on the basis of collaborative studies. The methods have better reproducibilities than the colorimetric methods currently recommended.     

植酸对控制水果打浆中VC损失的研究

研究植酸对控制草莓、猕猴桃和山楂果实打浆工序中VC损失的效应.结果表明,植酸对3种水果打浆工序中还原型VC和氧化型VC的保护效果不一,植酸可以明显提高山楂打浆中的还原型VC和氧化型VC保存率;对猕猴桃仅提高其氧化型VC保存率,不能提高还原型VC保存率.对草莓还原型VC和氧化型VC的保存效果则与猕猴桃相反.     

粮食脂肪酸值测定方法的研究进展

脂肪酸值是粮食储存品质的重要指标。本文简要介绍提取粮食游离脂肪酸的各种溶剂,对滴定法、比色法和色谱法等粮食脂肪酸值测定方法的优缺点及其研究进展也作了探讨。