pH elevation, acidification, acetification,
incomplete fermentation, ropiness, and slow
runoff time. Such infection may also be
directly or indirectly responsible for various
off-odors and biological hazes in finished
beer.
Lactobacillusis usually regarded as the
most troublesome genus of bacteria in the
brewery because its species represents a
potential spoilage hazard at the various
stages of production, including finished
beer. Other genera are less versatile under
brewery conditions; therefore, their spoilage
potential is more limiting. However, enter-
obacteria may have an impact on the fer-
mentation, flavor, and aroma of beer.
According to Stewart (1987), the most com-
mon techniques used for detecting and dif-
ferentiating the various brew contaminants
are selective and differential culture media
(either alone or in combination with cen-
trifugation) or millipore filtration, depend-
ing on the expected cell density and various
serologic techniques and impedance meas-
urement.
Construction Considerations
Sanitation is enhanced through the design
and construction of insect and rodent proof
construction materials such as concrete,
brick, and tile. The floors should be dense,
impervious, readily cleanable, and durable.
Preferred flooring materials are acid resist-
ant concrete or epoxies. A sufficient number
of grains should be provided to convey liq-
uid from all rooms. Rounded gutters are pre-
ferred to right angle corners and should
contain grid covers of corrosion resistant
materials. They should be screened to
exclude rodent entry.
Double or hollow walls and ceilings
should be avoided or have all areas tightly
sealed. Insulation should be completely
sealed into walls or ceilings. Unnecessary
recesses or ledges should be avoided because
they trap dirt and debris. If ledges are neces-
sary they should be beveled so that dirt and
wash water will slide off easily. Covered or
shatterproof lights are needed to reduce
physical hazards.
Equipment must be designed to protect
the product from contamination. Outside
fermentation tanks must be constructed to
protect against insect entry and damp are
dusty weather. It is acceptable to use food
grade plastic or stainless steel tanks, but the
use of threaded fittings is discouraged since
they can cause a cleaning problem.Control of Microbial Infection
Contamination may be controlled through
removing excess soil and microorganisms
that cause off-flavors. Although beer will
self-sterilize in 5 to 7 days, undesirable bacte-
ria, yeasts, and molds grow rapidly in freshly
cooled wort that is contaminated through
poor sanitation. Therefore, it is necessary to
clean and sanitize the brewery equipment
that processes the wort. Stanton (1971)
reported that clean kettles and coolers trans-
fer heat faster because 1 mm of soil on the
inner cooling surface is equivalent to 150
mm of steel. He has hypothesized that 1 mm
of soil could have a similar insulating effect.
Furthermore, high-speed equipment, such as
fillers, cappers, casers, and keggers, performs
more effectively if kept clean.
The most effective means of preventing
spoilage of beverage products is to control
infection by developing and maintaining a
comprehensive cleaning and sanitizing pro-
gram. A program can be developed by sani-
tation personnel or with the help of a reliable
sanitation consulting group or a dependable
cleaning compound and sanitizer supply
firm. Discussions in other chapters relating
to equipment and facility design, cleaning
equipment, cleaning compounds, and sanitiz-
ers should be reviewed to determine guide-
lines for the implementation of a sanitation