676 Part VI: Fermented Foods
30,000 hL/year pilot-scale system was purchased
and installed in their plant (Mensour et al. 1997).
The Alfa Laval maturation system has been imple-
mented in a medium-sized German brewery (Schäff/
Treuchtlingen) (Back et al. 1998). The obtained
beers yielded overall good analytical and sensorial
results.
Production of Alcohol-Free or Low-Alcohol
Beer
The classical technology to produce alcohol-free or
low-alcohol beer is based on the suppression of
alcohol formation by arrested batch fermentation
(Narziss et al. 1992). However, the resulting beers
are characterized by an undesirable wort aroma,
since the wort aldehydes have only been reduced to
a limited degree (Collin et al. 1991, Debourg et al.
1994, van Iersel et al. 1998). The reduction of these
wort aldehydes can be quickly achieved by a short
contact time with the immobilized yeast cells at a
low temperature, without undesirable cell growth
and ethanol production. A disadvantage of this
short-contact process is the production of only a
small amount of desirable esters.
Controlled ethanol production for low-alcohol
and alcohol-free beers has been successfully achiev-
ed by partial fermentation using DEAE cellulose as
the carrier material in a column reactor (Collin et al.
1991, Van Dieren 1995). This technology has been
successfully implemented by Bavaria Brewery (The
Netherlands) to produce malt beer on an industrial
scale (150,000 hL/year) (Pittner et al. 1993). Several
other companies—that is, Faxe (Denmark), Otta-
kringer (Austria) and a Spanish brewery—have also
implemented this technology (Mensour et al. 1997).
In Brewery Beck (Germany), a fluidized-bed pilot-
scale reactor (8 hL/day) filled with porous glass
beads was used for the continuous production of
nonalcohol beer (Aivasidis et al. 1991, Breiten-
bücher and Mistler 1995, Aivasidis 1996). Yeast
cells immobilized in silicon carbide rods and ar-
ranged in a multichannel loop reactor (Meura, Bel-
gium) have been used by Grolsch Brewery (The
Netherlands) and Guinness Brewery (Ireland) to
produce alcohol-free beer at the pilot scale (Van De
Winkel 1995).
Nuclear mutants ofS. cerevisiaethat are defec-
tive in the synthesis of tricarboxylic acid cycle
enzymes—that is, fumarase (Kaclíková et al. 1992)Table 29.5.Selection Criteria for Yeast Cell Immobilization Carrier Materials- High cell mass loading capacity
- Easy access to nutrient media
- Simple and gentle immobilization procedure
- Immobilization compounds approved for food applications
- High surface area-to-volume ratio
- Optimum mass transfer distance from flowing media to center of support
- Mechanical stability (compression, abrasion)
- Chemical stability
- Highly flexible: rapid start-up after shutdown
- Sterilizable and reusable
- Suitable for conventional reactor systems
- Low shear experienced by cells
- Easy separation of cells and carrier from media
- Readily upscalable
- Economically feasible (low capital and operating costs)
- Desired flavor profile and consistent product
- Complete attenuation
- Controlled oxygenation
- Control of contamination
- Controlled yeast growth
- Wide choice of yeast
Source:Nedovic and Willaert 2004.