摘要:

A colorimetric method for routine determination of reduced ascorbates in beer based on a kit from Boehringer Mannheim was evaluated. With slight modification, the assay was found to be well-suited for determining reduced ascorbates in beer. The limit of determination in beer was found to be 1.09 mg/L versus 0.31 mg/L for a liquid chromatographic electrochemical detection method (LCEC). The 95% sample confidence interval at 10 mg/L was±0.94 mg/L compared with±1.99 mg/L for the LCEC method. The slope of a standard curve was found to be within 2% of the theoretical value and statistically not significantly different. The method utilizes common laboratory equipment, does not suffer interference from beer constituents, is rapid and reproducible, and does not require the preparation of reagents or a standard curve.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0057

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

High-performance liquid chromatographic analysis ofα-acids in hops and iso-α-acids in wort samples from six breweries showed that between 30 and 75% of theα-acids originally added to the kettle can be found as iso acids in the finished wort. The variations are mainly due to differences in equipment but are also influenced by the hop product used. In the range 10.5–13.5°P, no relationship between hop utilization and original gravity was found. Cluster analysis of samples from 14 breweries showed that wort or beer samples (three types of beer) could be divided into three groups with varied ratios of isocohumulone to other isohumulones. The chemical composition of the groups remained relatively constant from wort to beer. Classification of the samples did not correspond to the level of hop utilization in the respective breweries.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0062

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

Various graphite furnace techniques were evaluated in order to develop an accurate, reliable method for the analysis of aluminum in beer. Both normal off-the-wall and platform atomization employing either direct concentration mode or method of additions resulted in inconsistent but always high recoveries for aluminum added to beer. Incorporating matrix modification, peak area integration rather than peak height measurement, use of the alternate wavelength 396.2 nm, and deuterium background correction in conjunction with platform atomization led to consistent recoveries of added aluminum (99–110%). These values were verified by the method of additions. A reliable atomic absorption method has been developed for the analysis of aluminum in beer.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0068

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The indictor microorganisms currently accepted for the detection of human fecal contamination in industrial wastewater are fecal coliforms in conjunction with fecal streptococci. As a secondary indicator,C. perfringensmay have some advantages over these when the sample is from a harsh environment, i.e., industrial waste, chlorinated water, or wastewater, because it has the ability to form spores that survive these types of environments. AlthoughC. perfringenshas been evaluated as an indicator microorganism by several researchers, the methodology historically available for its isolation limited its use. We evaluated water from two wastewater treatment plants over three months using the membrane filter technique for the isolation and enumeration ofC. perfringensas developed by Bisson and Cabelli in 1979 and found this microorganism to be useful as a secondary indicator of human fecal contamination in industrial wastewater.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0070

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The use of more than one lager yeast strain in a brewery poses the risk of cross-contamination with consequent problems in beer quality. In this work, conditions are reported that allow the detection of cross-contamination among three lager yeast strains used in this company's breweries by the use of selective inhibitors in solid media. The inhibitors used were bromocresol green, copper sulfate, basic fuchsin, streptomycin, and Actidione (cycloheximide). Contamination levels as low as 0.01% (one in 10,000) were detected in some cases.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0073

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

Frozen beer precipitates were usually formed when beer was kept for several days at−8 to−13°C. The precipitates were composed mainly ofβ-glucans, and their molecular weights ranged from 106to 103. The high molecular weight fraction (mol wt 106to 105) was similar to native barleyβ-glucans, which have a ratio ofβ-(1–3) toβ-(1–4) linkages of about 30:70. The medium molecular weight fraction (mol wt 105to 104) had a ratio of about 25:75, whereas the lower molecular weight fraction (mol wt 104to 105) was mostly composed ofβ-glucan withβ-(1–4) linkages. In brewing barley malt, two kinds of enzymes that catalyze degradation ofβ-glucan were found, namelyβ-(1–4)-d-glucanase (I) and (II). These enzymes can also synthesizeβ-(1–4) linkages. For example,β-(1–4)-d-glucanase(I) is able to transfer the cellotriose moiety to the nonreducing end glucosyl residue of another oligosaccharide to form insolubleβ-glucan. Lower and medium molecular weight fractions were estimated to be formed by both degradative and transferase-type reactions during the malting and mashing process. The solubility ofβ-glucan decreased with increasing ratios of theβ-(1–4) linkage inβ-glucan. In fact, the lower molecular weight fractions had lower solubilities than the high molecular weight fractions. The mechanisms of formation of frozen beer precipitates were estimated to be via increases in the alcohol concentration caused by the freeze concentration phenomenon. Consequently, the low solubility-lower molecular weight fraction precipitates and promotes the subsequent precipitation of high molecular fraction.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0077

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

This paper reports on the malting quality and agronomic performance of 46 proanthocyanidin-free barley lines selected from a cross of ANT 517 and the cultivar Harrington. The ANT 517 parent was the source of the proanthocyanidin-free character. Seed of 45 of 46 lines evaluated in 1986 with the vanillin-HCl test were 94–100% proanthocyanidin-free. In replicated trials grown under irrigation at Aberdeen, ID, in 1986 and 1987, 42 of 46 proanthocyanidin-free lines averaged higher in yield than the ANT 517 parent, and every line exceeded the ANT 517 parent in kernel plumpness. The highest yielding proanthocyanidin-free line, 85Y126, averaged 5,967 kg/ha during 1986–1987, or 98% of the yield for the cultivar Klages. One of the best malting lines, 85Y278, was superior to Klages in kernel plumpness, wort nitrogen/ malt nitrogen ratio, diastatic power, andα-amylase, but its malt extract was one percentage point lower than that of Klages. It yielded only 76% as much as Klages, but 4% more than ANT 517. Line 85Y72, with malting quality similar to 85Y278, yielded 84% of Klages and 115% of ANT 517 during 1986–1987. Many of the proanthocyanidin-free lines were equal or superior to Klages in most malting quality characteristics, but all were inferior to Klages in their malt extract percentages, and all lines likewise contained excessive protein. Nearly all lines were superior to the anthocyanidin-free cultivar Galant in malting quality. This research indicated no genetic linkage that might prevent the development of a high-yielding, proanthocyanidin-free barley with acceptable malting quality.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0082

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor