Technical Session 06: Quality Considerations Session
Hisao Koizumi, Asahi Breweries,Ltd.,Suita Brewery,Japan
Co-author(s): Yuichi Nakamura, Asahi Breweries, Ltd., Suita Brewery, Japan
ABSTRACT: In our breweries, large vessels with a capacity
of several thousand hectoliters are used to brew beer. For reasons of
cost-effectiveness, sanitary conditions, and appropriate cleaning, only
one sampling device is usually installed on the large vessels, and no
assurance is given that the sampled liquid taken from the device
represents the whole beer in the large vessel. Therefore, we developed
equipment to directly sample the beer in the large vessel from several
positions at different heights. This paper reports on the application of
the equipment to the 5,000 hL fermentation vessel, which is filled with
four batches of wort prepared as 1,250 hL each for fermentation. Four
perfluoro alkoxyl alkane resin tubes were extended from the vessel
bottom to the intermediate heights between the liquid levels, where four
batches of 1,250 hL wort reached, respectively, and the fermenting beer
was sampled from each layer. The bottommost layer (3.8 m above the
vessel bottom) was designated sample #1, the 9.2 m high position was
sample #2, the 12.5 m was sample #3, and the topmost layer (15.8 m high)
was sample #4, and the fermenting beer and yeast were analyzed. We used
the equipment to compare the uniform pitching method, where the same
amount of yeast and air were pitched into the first to fourth batches of
wort, and the early pitching method, where the same amount of yeast and
air were pitched into the first to third batches of wort, while neither
yeast nor air was injected into the fourth batch of wort. Under the
uniform pitching condition, the temperature, number of yeast cells,
specific gravity, and amino nitrogen level during fermentation were
almost the same at all of the four positions in the fermentation vessel.
However, in the case of the early pitching method, the bottommost layer
and the upper three layers were not blended, and fermentation started
as each layer was kept independent. After around 50–60 hr from
initiation of fermentation, convection was generated, and the 5,000 hL
of fermenting beer became uniform. According to the sensory tests, the
beer brewed by the early pitching method had a higher rating with
smaller variations. The sampling equipment we developed for this enabled
us to sample fermenting beer and yeast from an arbitrary height at any
time and evaluate the distribution and uniformity of the fermenting beer
components, temperature, and yeast cells, which was applicable to
improvement of beer flavor in practical brewing processes.
Hisao
Koizumi received an M.S. degree in biotechnology from Hiroshima
University, Japan. He began employment with Asahi Breweries, Ltd., in
April 2001. After working as a researcher in the laboratory, he was
transferred to the brewing section of the Suita brewery.
VIEW PRESENTATION 20
