Abstract
Fermentation is the most time consuming step in the
production of beer and therefore the effective use of
fermentation vessels is a crucial element in brewing
economy. One means of increasing the productivity of a
batch process is to convert it to a continuous one.
Experiments in continuous fermentation emerged during the
1950s and 1960s, but by the end of 1970s most of them had
been closed down. Immobilization technique revitalised
continuous fermentation research in the 1980s and led to
industrial applications in the secondary fermentation and
in the production of low-alcohol beers.
This work demonstrated that an immobilized, continuous
main fermentation is a feasible process for production of
lager beer. The immobilized main fermentation was stable
for more than 14 months both in fermentation efficiency
and in aroma compound formation. The formation of aroma
compounds could be controlled by varying the composition
and amount of gas feed into the first fermentation stage.
The division of immobilized main fermentation into an
aerobic and an anaerobic stage appeared to solve problems
related to yeast growth and viability.
The carrier material affected the formation of flavour
compounds in small-scale fermentations. Moreover the
effect varied with the yeast strain used. The carrier
affected the economy of immobilized fermentation: the
carrier cost could be as high as one third of the
investment. When a cheap carrier is used the investment
cost for a continuous, immobilized process was estimated
to be only about 70% of the investment cost of a batch
process.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 9 Mar 2001 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-5840-5 |
Electronic ISBNs | 951-38-5841-3 |
Publication status | Published - 2001 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- beverages
- beer
- brewing
- primary fermentation
- immobilized yeasts
- carriers
- stability
- flavours
- microbes
- contamination