摘要:

A procedure is described for the routine gas chromatographic analysis of beer headspace volatiles which requires minimal operator time. The reproducibility of the procedure is illustrated for 12 components. A method for predicting triangular taste panel performance, using the t-statistics calculated from the“Per Cent of the Total Peak Area”(PTPA) and pooled standard deviations from 25 replicate analyses, is introduced. Correlation between the PTPA method and triangular taste panel results is demonstrated.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006176

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The reproducibility of carbon disulfide extraction was improved by decreasing the proportion of salt added and by standardizing the conditions. A new liquid phase and the use of glass columns and Teflon-faced septa led to better gas chromatographic separation and reproducibility. An autoinjector and a computing integrator provided further improvements and greater convenience of operation. A computer program was developed which prints out the results for each peak and produces a statistical summary of repeat determinations. It also calculates the probable flavor significance of the analysis employing known flavor thresholds and interactions. The use of the method is illustrated with a study of the course of commercial fermentations in open and closed vessels. A number of domestic and imported beers and malt liquors were also analyzed.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006177

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Determination of deterioration of bottled beer in trade packages may be a rather complicated task, so an investigation was made of formation of furfural as an index of change. Color increase, sometimes advocated as a measurement of oxidation or browning, was followed concurrently. A fluorometric method for the determination of furfural was used, based on the fact that furfural reacts with o-aminothiophenol to form 2-(2-furyl) benzothiazole which shows an intense fluorescence in strong acid solution. The furfural was collected by steam distillation in a micro-Kjeldahl, which separated the furfural from those other carbonyl compounds which would otherwise interfere. The furfural content of fresh, unpasteurized beers tested was below 15μg/l., but the level increased significantly on pasteurization and dramatically on exposure to warm ambient temperatures. Color was affected far less. Increases in furfural in beer held at 25°C followed a first-order reaction rate pattern, but those in beer at 40°C were greatly accelerated and appeared to be by different mechanisms or reactions. There is a correlation between major changes in furfural content and decreases in taste panel scores, though the furfural levels were never above the taste threshold for this compound.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006178

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

An automated procedure for determining free amino nitrogen was developed by adopting the EBC- and ASBC-recommended ninhydrin method. The procedure was successfully applied to assess the contents of free amino nitrogen in the media at various stages of fermentation. Uptake of amino nitrogen and formation of fusel alcohols were studied in four experimental mashes which contained various amounts of nitrogenous compounds and carbohydrates. Results indicate that ale yeast takes up more amino nitrogen than lager yeast. Evidence also suggests that the bottom-fermenting yeast is capable of synthesizing more nitrogenous substances than the top-fermenting yeast under corresponding conditions. At the level of amino nitrogen examined (100–300 mg/l.), there is no positive correlation between the nitrogen concentration and the amount of fusel alcohols formed. More n-propanol and isobutanol but less 2-methyl-1-butanol were formed in ale than in lager brewed with the same wort. When an appreciable amount of sugar (mainly glucose) was added to the wort, the adjunct appeared to suppress the formation of n-propanol but promote that of 3-methyl-1-butanol.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006179

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Overall sulfur balance and sulfate metabolism during fermentation of brewery wort by ale and lager yeast have been studied by [35S]sulfate labeling experiments. Ale yeast derived 40 and 27% of the total sulfur assimilated during stirred flask and unstirred column fermentations, respectively, from wort sulfate. The corresponding values for lager yeast were 41 and 21%. The contributions of sulfate to H2S evolved in the fermentor gases, and to medium SO2 formed during fermentation, have been examined. Ale fermentations produced<μg S of fermentor gas H2S/I. medium and<0.2μg S of medium SO2/I. medium. Stirred flask lager fermentations evolved an average of 62μg H2S/I. of medium, 72% of which was derived from sulfate. Sulfate-derived H2S constituted 64% of the total H2S evolved during unstirred column fermentations (130μg H2S/I. medium). The effects of individually added amino acids (L-methionine, L-threonine, and L-cysteine) and heavy metals (Fe, Cu, and Zn) have been studied and are discussed in terms of literature results and yeast sulfur metabolism. The total bound SO2levels averaged 0.17μgS/g and 11μgS/g in beer from stirred flask and unstirred column lager fermentations, respectively. Radiochemical tracer experiments showed that all of the SO2formed in the latter experiments was derived from wort sulfate.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006180

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Of the volatile acids known in beer, acetic acid appears to be the most abundant. The acetate content of lager beers has been reported in the range of 20 to 150 mg/1. The effect of the following variables on the formation of acetate during fermentation was studied: yeast strain, wort aeration, pitching rate, and fermentation temperature. The results were evaluated using biometric analysis. On the basis of the analysis of variance, the influence of wort aeration is less than that of the yeast strain, whereas pitching rate and fermentation temperature have more importance than the yeast strain. Based on multiple regression analysis, 80% of all the acetate produced can be attributed to the following factors: glucose + fructose + sucrose, absorbed isoleucine, absorbed tryptophan, excreted sodium, utilized manganese, absorbed arginine, yeast growth, utilized calcium, utilized magnesium, and fermented maltose.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006181

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

A quantitative method for the evaluation of polyphenoloxidase in barley and malt has been devised. It consists of extraction, concentration of the enzyme, and measurement of the activity by the polarographic method. Polyphenoloxidase activity in different varieties of barley and malt was determined. Further, the enzyme was partially purified and its properties studied. This enzyme catalyzes the oxidation of different polyphenols. It is inhibited by cyanide, 4-nitrocatechol, and 1,3-naphthalenediol. In brief, the enzyme behaves like a typical polyphenoloxidase.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006182

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The object of this work was to develop a simple, rapid, and precise method for the determination of fermentable sugars in brewing materials. A single peak for each sugar is obtained by addition of hydroxylamine hydrochloride to form the sugar oxime prior to formation of the trimethylsilyl ether. By using an excess of hexamethyldisilazane, wort and corn syrup samples could be analyzed without the need of freeze-drying, although this was necessary to obtain the sensitivity required to analyze beer. Methods are given for the analyses of wort, corn syrup, and beer. Data are given for injection and analysis precision of these methods. Their application to brewing problems is shown by following a fermentation and analyzing a beer high in real fermentable extract.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006183

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor