摘要:

Certain malts cause premature flocculation of yeast in brewery fermentations. Initial results suggested that the isolated husk factor(s) putatively responsible for premature flocculation bind to yeast cell walls. Because barley contains lectins, and lectins by definition bind specific sugars, it is probable that, if present in adequate concentrations, they would be instrumental in producing premature flocculation by binding to yeast cell walls. In the first part of this work, a barley lectin was isolated by affinity chromatography and shown to survive the malting and brewing process, but the purified lectin was not found to be implicated in premature flocculation. In the second part of this study, we used yeast that had undergone premature flocculation as a form of affinity chromatography column to isolate the factor(s) in malt husk responsible for premature flocculation. Glucose, mannose,α-methylmannoside, andN-acetylglucosamine were able to release factor(s) from prematurely flocculated yeast. This factor(s) caused early flocculation when added back to normal fermentations. Premature flocculation could be prevented by preincubating the flocculation factor(s) from malt husk with the above sugars. Lactose, however, was unable to release any flocculation factors from the yeast and was also unable to prevent early flocculation when incubated with the malt husk factor. The malt husk factor has lectin-like sugar specificities. Further corroborative work is underway.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0029

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The effects of hop variety on the beer volatile constituents resulting from kettle hopping were studied. Three specially brewed beers, each hopped with single varieties of hops (Hallertau, Galena, and Fuggles, respectively), and an unhopped beer were analyzed by a headspace gas chromatographic method. Hop varietal differences and kettle hopping effects were observed among the beer headspace chromatograms of these four beers. Peaks, which were categorized as unique, largest, smallest, and absent, were tabulated for each hopped and unhopped beer. More peaks were observed in the gas chromatographic profile of the Hallertau hopped beer than in any of the others.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0035

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The analysis of total protein is critical to the evaluation of many constituents and by-products of the brewing process. Currently, the most comon method in use for analysis of total protein is Kjeldahl digestion. The Kjeldahl digestion method requires significant time input in each analysis and involves the use of potentially hazardous chemicals. The alternative method presented here uses the LECO FP-228 Nitrogen Determinator to analyze total protein or total nitrogen. This instrumental method involves combustion of a sample in an oxygen atmosphere followed by a series of catalytic reactions that result in nitrogen gas. This gas is utilized for determining the total protein. The use of this instrumental method significantly reduces the analysis time and eliminates the use of potentially hazardous chemicals in the analysis. Not only do the results from the Nitrogen Determinator correlate with the Kjeldahl method, but there is less variance using the Nitrogen Determinator.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0042

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The malting and brewing quality of anthocyanogen-free mutants and segregates from crosses of barley were studied. The samples were brewed by a double mashing procedure using the hop variety Cascade and 25% adjunct (yellow corn grits). Some differences in anthocyanogens, chill haze stability, beer color, and other malting and brewing quality parameters were shown between mutants and wild-type barley beers. Most of the differences were at acceptable levels. Chill haze stability was excellent fromantmutant and recombinant line beers. Some of the beer brewed with theantmutants, however, had lower brewhouse yield and somewhat darker color than beer brewed with regular malt.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0044

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The relationship between free radicals and the staling of beer was studied. Hydrogen peroxide was generated when beer was incubated at 60°C. When examined by electron spin resonance spectroscopic analysis, the hyperfine splitting constants of phenyl-tert-butylnitrone adducts of beer incubated at 60°C with H2O2were close to those of beer without H2O2. The production of aldehydes and the degradation of isohumulones during the incubation of beer were accelerated by the addition of H2O2or by irradiation withγ-rays. They were inhibited by the addition of ethylenediaminetetraacetic acid. It is suggested, therefore, that H2O2generated during the incubation of beer could interact with the metals present to play an important role in radical reactions in beer.

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0049

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0361-0470    

DOI:10.1094/ASBCJ-47-0054

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor