摘要:

2-Thiobarbituric acid (TBA) was used to measure the degree of beer staling. Optimum conditions were established for the reaction between TBA and stale flavor constituents present in beer, beer extracts, and beer distillates. A correlation existed between the extent of beer staling and TBA values. Results obtained on fresh and stored beers indicated that the TBA test may be used to determine the concentration of TBA reactive compounds present in beer as well as the quantity of TBA reactive compounds that can be produced in a beer upon aging. Several factors influencing the formation of TBA reactive compounds in beer were studied. A number of commercial beers were analyzed by the TBA procedure and were found to possess different levels of TBA reactive compounds. It was also found that TBA test may be used not only to characterize different brands of beer but also to follow product consistency and uniformity.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006184

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

High-performance liquid chromatographic (HPLC) methods were used to measure several low-volatile flavor compounds of beer as well as those introduced into beer from processing aids and packages. Superiority of the HPLC methods over the conventional methods used for the measurement of these compounds was shown in respect to speed, convenience, and specificity of such analyses.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006185

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Flocculent and nonflocculent strains ofSaccharomyces carlsbergensis(lager yeast) gave different concentrations of aromatic higher alcohols. Tryptophol levels formed by nonflocculent strains were double the concentration of the flocculent strains. Bottom-cropping strains ofS. cerevisiae(ale yeast) formedlowerlevels of these compounds than either top-cropping or nonflocculent strains. The differences were again most significant in tryptophol levels. Glucose addition to fermentations withbottom-cropping aleyeasts had the same influence on the formation of these compounds as on lager yeasts,i.e., concentration increased in direct proportion to the additional increase in glucose.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006186

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Lyophilization was compared with slant culturing and with storage under oil as a means of preservingSaccharomyces uvarum.Several types of suspending media were tested, and horse serum, the glucose-supplemented horse serum“Mist, desiccans,”and skim milk were used for a long-term study. A range of shelling temperatures was investigated and−30°C was found optimal in terms of viability. Samples were revived every 3 months for a 24-month period. Mutation rates, assimilation and fermentation characteristics, growth requirements, gas-liquid chromatographic profiles from CS2extracts of experimental fermentations, and organoleptic comparisons of pilot beers all indicated that lyophilization was comparable to the other storage methods. Although viability decreased significantly over the test period, sufficient normal, viable cells survived to maintain a reliable stock.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006187

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The purpose of this work was to study the yeast enzymes involved in the removal of diacetyl and structurally related compounds in beer. Yeast alcohol dehydrogenase (ADH) catalyzes the reduction of three vicinal dicarbonyl compounds found in beer: methyl glyoxal. diacetyl, and 2,3-pentanedione. The pH optimum for these activities is 6–6.5. While ADH uses these compounds with equal facility, they are poor substrates compared to acetaldehyde. ADH does not interconvert acetoin and 2,3-butanediol or acetol and 1,2-propanediol. Yeast has other enzyme activity which reduces acetoin, acetol, diacetyl, and 2,3-pentanedione. Thus, the latter two compounds, which are important flavor-influencing vicinal diketones, are reduced by more than one enzyme. This other enzyme activity is also capable of oxidizing 2,3-butanediol and 2,3-pentancdiol. The oxidation (dehydrogenation) of butanediol is catalyzed by more than one enzyme.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006188

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Recycling of excess yeast to the mash mixer has been examined on a pilot scale as a means of eliminating this waste stream. The effects on brewing processes and on beer qualities are minimal, and other benefits such as extract recovery accrue.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006189

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Concentrations of volatile esters and acids decrease in successive cycles when the same yeast is used repeatedly to ferment pure carbohydrate substrates. The effect is independent of the sugar being fermented. Maltose produced slightly smaller amounts of several volatiles than did fructose, glucose, or sucrose. Corn syrup produced more than the individual sugars, an effect not merely due to the presence of glucose and maltose together. Yeast type markedly affects the production of volatile substances in these systems. The formation of individual volatile substances in malt and adjunct worts is influenced by agitation and yeast concentrations, different volatiles behaving differently according to the conditions used.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006190

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Corn and barley syrups manufactured in different ways varied in fermentability. Tendencies observed with conventional or low-gravity worts were usually accentuated at starter solids of 18°P and greater. Carbohydrate composition appeared to be a factor inasmuch as decreased fermentability was observed when high-gravity wort glucose was in excess of 10% (of the total carbohydrate). Agitation and limited aeration in the early stage of fermentation each increased rate and degree of attenuation of wort containing a specific barley syrup. However, the combination of the two maximized the effect. High-gravity worts produced beers with normal ethyl acetate contents. While not tabulated, levels of higher alcohols were also normal. Examination of pitching rate suggested that about 1.4×107cells ml of high-gravity wort gave best results.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006191

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The separation of hop-derived compounds with several high-performance liquid chromatography techniques was studied. A system employing ion-exchange materials was developed which clearly resolvesβ-,α-, and iso-α-acids in less than 2 hr without gradient elution. Adsorption and partition columns can also separate the major groups of hop compounds. Reverse-phase partition chromatography is capable of resolving thecis-andtrans-iso-α-acids.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006192

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor