期刊
JOURNAL OF THE INSTITUTE OF BREWING
卷 114, 期 3, 页码 270-276出版社
INST BREWING
DOI: 10.1002/j.2050-0416.2008.tb00338.x
关键词
Acidification power; brewery practice; optimised AP test; wort attenuation; yeast cropping; yeast quality
资金
- CR Ministry of Education, Youth and Sports [1M0570]
- Institutional Research Concepts [AV0Z50200510, MSM0021620835, MSM6019369701]
The optimised acidification power test (APT) of brewer's yeast quality includes storing the yeast Slurry at 2 degrees C under beer (AP remains constant for up to 6 days), a 15 min sample equilibration to room temperature, decantation, and washing by triple centrifugation in deionised water. The final yeast pellet keeps its AP for up to 6 h at room temperature under water and thus the APT does not need to be performed immediately after yeast collection. The correct AP value (maximum acidification produced by given yeast) is determined at 25 +/- 0.1 degrees C in a 15 mL sample containing >= 5% glucose and >= 1.5 g yeast wet weight. The cell concentration is conveniently measured as absorbance (A(660)). Cell flocculation and/or sedimentation that can distort APT results can be prevented by stirring the sample at >= 200 rpm. The AP of yeast of different generations used to pitch brewery fermentations in cylindroconical tanks had a very low correlation with the wort half-attenuation time (T-1/2) due to large scatter, while each yeast generation separately showed a clear T-1/2-AP relationship. The lowest AP of yeast cropped from cylindroconical tanks was displayed by the first cropped fraction. Post-cropping cooling had no effect on AP. Variations in pitching yeast vitality and their effect on the outcome of a brewery fermentation can be masked by variations in pitching rate, wort composition, ambient conditions in the cylindroconical tanks and other factors.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据