1. By Dmitry Liskin Norfolk, VA October 2012
Biochemistry of Beer

2. What is Beer?
According to Rheinheitsgebot (1516) beer should only contain:
Water
Barley
Hops
Yeast was discovered in 1800 by L. Pasteur

3. origin of beer Beer-like beverages appeared around 10,000 BC
First evidence points at Mesopotamia region
Is said to be responsible for development of agriculture

4. water Hardness Other ions Carbonate – temporary Sulfate – permanent
Gave birth to beers with malty, smooth finish
Munich, Dublin, London, St.Louis, Milwaukee
Sulfate – permanent
Bitter, pale beers
Burton-on-Trent
Other ions
zinc, copper are necessary for fermentation
Iron, manganese and chloride will cause flavor problems

5. barley Malt: barley that has been sprouted and dried Color Aroma
Golden to black
Aroma
Bready, malty, nutty, toasty, roasty
Flavor
Caramel, toffee, molasses, coffee
These characteristics develop due
to non-enzymatic browning reactions

6. Caramelization Thermal decomposition of sugar, pyrolysis
110 oC – 180 oC
Low-moisture
Produces a variety of products

7. Maillard reactions Reaction between amino acid and sugar
48 oC – 230 oC

8. hops
Beer preservation
Bitterness
Flavor
Aroma

9. yeast Brewers’ best kept secret Converts fermentable sugars to alcohol
Top fermenting – ale; bottom - lager
Contributes to flavor
with other byproducts
Fusel alcohols
Esters
Aldehydes

10. Classic Beer styles Bitters and Pale ale Stout Scottish ale
India Pale ale
Lager

11. Bitter and Pale Ale The beer of an Empire (1702 – 1714)
Use of coal gave birth to pale malt
Firm hop bitterness
Low hop character
Touch of caramel from malt (bitters)
Light fruity character from yeast
About 5% alcohol

12. Stout Dark beer with roasty character
Refreshing low alcohol to warming high gravity beers
Dry stout
Sweet stout
Oatmeal stout
Imperial stout

13. Scottish ale Malt sweetness, smoky Clean finish Low bitterness
Wide range of alcohol levels
60/-, 70/- and 80/-

14. India pale ale (IPA) Bitter, hoppy ale Crisp finish
Malty, some caramel flavor
Moderately strong
(5% - 7.5% alcohol)

15. lager Malt focused beers Low hop character 4.4% – 5.4% alcohol
Clean finish
Most food friendly style

16. Making of beer - mashing
Base malt with specialty grains
Mashing
Hydration of malt
Gelatinization of starches
Release of natural enzymes
Conversion of starch to
fermentable sugars

17. Enzymatic activity Starch conversion (60 oC – 75 oC) Protein rest
Alpha-amylase
Beta-amylase
Limit-dextrinase
Alpha-glucosidase
Protein rest
Proteases
peptidases

18. Boiling the wort Beer clarity Hop additions
The hot break – protein coagulation
The cold break – protein coagulation
Hop additions
Bitterness – min
Hop flavor – 20 min
Hop aroma – 5 min or dryhopping

19. Alpha acid isomerization
Alpha acids = Bitterness of beer
Humulone
Cohumulone
Adhumulone
Measured by IBU’s (International Bittering Unit)
1 IBU = 1 mg alpha acid per 1 L

20. Flavor and aroma compounds
Myrcene – pungent
Humulene – delicate and refined
Caryophyllene oxide – herbal/spicy

21. fermentation Beer is born when yeast is pitched Yeast characteristics
Type – Lager, Ale, Weizen
Flavor – malty, fruity, woody, etc.
Attenuation – degree of fermentation
Temperature – impacts flavor
Flocculation – precipitation of yeast
Sugar, oxygen, nitrogen and minerals are needed

22. Yeast at work Adaptation Attenuation Conditioning High growth
Aerobic process
A few hours
Attenuation
Production of alcohol
Anaerobic process
Fermentation of simple sugars
4 – 10 days
Conditioning
Conversion of byproducts to ethanol
Flocculation

23. Yeast byproducts Diacetyl and pentadione – buttery flavor
Acetaldehyde – green apple aroma and flavor
Fusel alcohols – oxidation to esters; fruity aroma
These byproducts will be metabolized during conditioning stage

24. Finished product Water Malt Hops Yeast
Hardness affects mash pH and taste
Malt
Color, flavor, aroma and body
Hops
Preservation
Bitterness, flavor, aroma
Yeast
Alcohol, flavor, aroma, clarity
Combination of these factors gives the finished product
Complex flavors are desired while complicated ones to be avoided

25. acknowledgements Referenced literature O’Connor Brewery
Randy Mosher “Radical Brewing”
John Palmer “How to Brew”
Ray Daniels “Designing Great Beers”
Jamil Zainasheff and John Palmer “Brewing Classic Styles”
BYO “Brew Your Own” magazine
O’Connor Brewery
Christopher Newport University department of Molecular Biology and Chemistry
Fellow brewers