Microbiology of Beer Production

1
Microbiology of Beer Production
2
Beer was discovered by the a. Sumerians
6000-4000 BC b. Egyptians 2000 BC c. Romans
500 BC d. Germans 1300s e. colonial
Americans 1600s
3
Why was beer important to early cultures? a. to
escape the pressures of a hard life b. for
religious rites c. for nutrition and health d.
to preserve food
4
Interesting Beer History A 3900-year old
Sumerian poem honoring the brewing goddess
Ninkasi contains the oldest surviving beer
recipe, describing the production of beer from
barley via bread.The Babylonian Code of
Hammurabi required that tavern-keepers who
diluted or overcharged for beer should be put to
death. During medieval times fasting monks
drank beer for nutrition as well as a tasty
drink. Historians report that each monk was
allowed to have 5 liters of beer per day. The
Pilgrim Fathers landed at Plymouth Rock, instead
of further south, partly because they were out of
beer. Journal entry dated December 19, 1620
said "We could not take time for further search
or consideration our victuals being much spent,
especially our beer".
5
Foods produced using microorganisms - cheese,
buttermilk, sour cream, yogurt - bread (pizza
crust) - soy sauce, miso, vinegar - sauerkraut,
kimchi, pickles - beer, wine, rootbeer, ginger
ale (actually the soft-drinks are now prepared
commercially without brewing or fermentation)
6
Micro organisms too small to be seen without a
microscope 0.5 - 2.0 µm (micrometers or microns)
in size

• Bacteria (kingdom Monera) single-celled
• Yeasts, Molds, Mushrooms (kingdom Fungi)
  single-celled (yeasts) or multicellular
• Protozoans (kingdom Animalia), single-celled
  animals
• Viruses, Prions (nonliving particles)

Magnified 1000x
7
The microorganisms that produce beer are a.
bacteria b. fungi c. protozoans d. viruses
8
Beer is produced using the natural process of a.
pasteurization b. fermentation c.
decomposition d. photosynthesis
9
Fermentation
Part of the process which microbes use to produce
ENERGY when oxygen is unavailable (anaerobic)
lactic acid or alcohol is a byproduct milk
products lactose ? lactic acid sugary
solutions glucose ? CO2 EtOH
10
Beer Production 101

• Barley germinated in water produces a sweet
  syrup, termed malting. The barley malting
  process lasts for forty-eight hours.
• The sprouted barley grain (malt) is then
  roasted. A longer, higher roast produces a
  darker, more flavorful barley, hence a darker,
  more flavorful beer. Conversely, a lower, shorter
  roast produces a less flavorful beer.
• The roasted barley kernels are ground and mixed
  with water to form a mash. Enzymes in the grain
  convert the starches of the mashed grains into
  sugar. The sweet liquid is called a wort.
• Wort is boiled and Hops are added to create a
  hopped wort.
• 5) The liquid is cooled to the right temp yeast
  are added.

11
Louis Pasteur, 1860s - Beer wine was going sour!

• Showed that fermentation was an anaerobic process
  carried out by microorganisms
• Showed certain organisms produced lactic acid,
  others produced alcohol
• Discovered that heating the solution prevented
  souring of wine during aging, extended shelf life
  of beer milk

Later germ theory of disease, anthrax rabies
vaccines
12
Pasteurization revolutionized the beer
industry it also changed the taste but since
beer could now be bottled and shipped all
overconsidered a minor detail Draft beer
nonpasteurized Bottled beer pasteurized Filtrati
on - 1959 the Adolph Coors company figured out
how to filter out leftover yeast bacteria
without heat, thus preserving flavor Japanese
developed a better ceramic filter Sapporo
Draft Anheuser-Busch company adopted filtration
methods Miller Draft Most American breweries
still employ pasteurization methods.
13

• Q Whats the alcohol content of typical
  American beers?
• A 3.6-3.8 by weight (4-5 by volume)
• Q What about "light" beer?
• A between 2.3 and 3.2 by weight (2.8 - 4 by
  volume)
• Q Why is the alcohol content of beer so low?
• A CO2 build up (too much pressure will stop
  yeast from fermenting)
• Yeast runs out of sugar (can add sugar to
  increase alcohol content)
• But - at 15-20 ETOH the alcohol level kills the
  yeast

14
Assignment

• Due in cluster Tuesday morning, 11/22
• Minimum of 2 page LLOG (described below)
• Minimum of 1 full page to consist of one topic
  related to beer production that you do research
  and expand on go into further depth (at least 3
  credible sources)
• ½ page on one aspect related to the cultural
  importance of fermentation
• ½ page on take-away, hardest thing, connection,
  competency.
• Remember CONCISENESS and QUALITY CONTENT are
  important qualities in writing about science!