摘要:

A rapid, sensitive firefly bioluminescence ATP assay using a liquid scintillation counter for measurement of assay light output is described. The use of partially purified luciferase and synthetic D-luciferin in this assay permits the detection of as little as 10−16moles ATP and as few as 10 yeast cells. The assay light output is directly proportional to the quantity of ATP from at least 10 to 104fmol and is on scale throughout this range. The method developed for detection and enumeration of viable microorganisms, which requires only a few minutes per sample, involves extraction of the cellular ATP with DMSO at room temperature and estimation of the ATP by the bioluminescence assay—for dilute suspensions, prior concentration and isolation of the cells by membrane filtration is necessary. The ATP contents of a selection of yeast and bacteria determined using this technique are reported. A linear relation between quantity of ATP and number of yeast cells is demonstrated, and the changes in intracellular yeast ATP pools during fermentation of wort by ale and lager yeast are presented. A number of other possible applications of this ATP assay in brewing research, development, and microbiological quality control are evaluated and/or discussed.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006214

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Blotter yeast samples, liquid yeast samples, unfinished beer samples, unpasteurized beer samples, and some miscellaneous samples were tested for the presence of wild yeasts. By the combined use of lysine medium and LWYM, varying numbers of wild yeast contaminants, including wildSaccharomycesandnon-Saccharomycesspecies, were detected. The levels of wild yeast contamination in some samples were very high at such levels, spoilage was quite possible. It is suggested that wild yeast contamination problems in the brewery should not be ignored and that the detection of wild yeasts should be emphasized in the brewery quality control program.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006215

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Six brands of membrane filters (Gelman, Membra-Fil, Millipore, Nuclepore, Oxoid, and Sartorius) were evaluated for recovering contaminating microorganisms from beer. All filters were of the 0.40 to 0.45-μpore size. Three different lots were tested for each brand. Beer samples were inoculated with typical contaminant microorganisms, and these were then filtered and recoveries were calculated. Five of the six brands were generally equivalent. Only one brand had a consistently lower recovery. All of the brands tested were consistent from lot-to-lot, but showed considerable variation from organism-to-organism.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006216

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

A 50% aqueous-ethanolic extract of malt was partially dissolved in methanol and the insoluble residue acetylated. The products of acetylation were taken up in chloroform and chromatographed on silica gel. The chloroform eluate was subjected to preparative thin-layer chromatography (TLC) on silica gel yielding a number of phenolics. Acetylated (+)-catechin, (–)-epicatechin, and procyanidins B were identified by comparing their nuclear magnetic resonance (NMR) spectra with those of the synthetic reference compounds. In another procedure, the 50% aqueous-ethanolic malt extract was treated with water and the insoluble portion triturated with methanol. The residue was fractionated by acetone extraction and the two portions (soluble and insoluble) were acetylated. Procyanidins of B and A types were identified by NMR after TLC separation on silica gel. Beer was extracted with ethyl acetate, and procyanidins of B and A types were identified by NMR following acetylation and TLC. In another procedure, beer was passed through Nylon-66, and procyanidin B-3 and a catechin trimer were identified by NMR following extraction, chromatography on Sephadex LH-20, and acetylation. Desorption of Nylon-66 beer tanninogen adsorbate was also performed by using 50% aqueous dimethylformamide.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006217

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Proton magnetic resonance spectroscopy has shown that the congener distribution of theα- andβ-acids present in four new varieties of hops varies considerably. There is no direct correlation between their congener distribution and brewing performance. Brewing studies have shown that the new varieties, which all contain high levels of a-acids, are equally suitable as copper (kettle) hops and can also be used to impart a pleasant hop character to beer.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006218

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

A radio-dilution technique has been developed for estimating levels of dimeric polyphenols in barley, malt, wort, and beer. Levels present in a number of different cultivars of barley vary from 130 to 350 mg/kg. When barley is malted, the loss of dimeric polyphenols is normally less than 15%. However, large losses of dimers occur during mashing and wort boiling, and smaller losses usually take place during fermentation and conditioning. The higher the level of dimeric polyphenols in the malt, the higher the level in the derived beer.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006219

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The influence of steeping degree, germination time, germination temperature, and kilning temperature on adenine, adenosine, cytidine, cytosine, guanine, guanosine, hypoxanthine, inosine + thymine, thymidine + uracil, and uridine of malt was investigated. A column chromatographic method was used. The variation of the technological conditions leads to individual effects in increasing or decreasing the nucleobases and nucleosides. Most of the nucleic acid derivatives vary strongly in pale lager malt, dark lager malt, and wheat malt. The biometric evaluation by means of stepwise multiple regression analysis shows that close relationships exist between malt protein, extract yield,α-amylase, diastatic power, wort viscosity, malt hardness, and protein modification on one hand and the individual nucleobases and nucleosides on the other hand. Because the nucleic acid derivatives represent about 8 to 9% of the nitrogenous compounds of malt, it would be worthwhile to study in more detail the pattern of these components at mashing and during fermentation.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006220

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

Collapsing beer foam produces a liquid and a suspended precipitate. Both the collapsed foam-liquid and foam-precipitate were obtained from unhopped beer and from unhopped beer plus reduced isohumulone. A dual-column gel chromatographic method was used to separate the foam fractions. The resulting molecular weight distribution of the proteins was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectricfocusing was also used to further resolve collected peaks. Characteristic profiles and differences in various foam components are presented. Evidence suggests the existence of an isohumulone-protein complex in the foam precipitate.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006221

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

摘要:

The prediction of chill stability of beer is important in relation to the intensity and type of treatment which must be given to the beer. Our objective was to develop methods to predict this quickly. The chief possibilities for such methods are based on the alcohol-cooling test, in which alcohol is added to beer which is then chilled to low temperatures to form a haze. The equipment using the alcohol-cooling test allows direct prediction of haze stability, which is well correlated with practical observations, to be made in 1 hr. The equipment, based on additions of polyvinylpyrrolidone or gallotannin, has made it possible to measure both tannoids and sensitive proteins continuously and accurately so that, in conjunction with the alcohol-cooling test, it serves to indicate appropriate treatments. Rapid prediction of haze potential of beer is possible, and continuous assessments can be made of tannins and sensitive proteins.

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006222

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor

ISSN:0361-0470    

DOI:10.1080/03610470.1976.12006223

出版商:Taylor&Francis    

年代:1976

数据来源: Taylor