The science of malting, brewing, and fermenting beer. Oct 6, 2010. Protein : a chain made up of 20 different amino acids from a few to as many as 34,350 residues. α -amylase. DNA. transcription. translation. RNA. Temperature effects on biology and chemistry.
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Protein: a chain made up of 20 different amino acids from a few to as many as 34,350 residues
The Structure and Properties of Water
D. Eisenberg and W. Kauzmann
glucose and other sugars
lactic acid (-198 kJ/mol)
ethanol + CO2
R = some chemical group
A member of the grass family. It is a self-pollinating, diploid species with 14 chromosomes. The wild ancestor of domesticated barley, Hordeum vulgare subsp. spontaneum, is abundant in grasslands and woodlands throughout the Fertile Crescent and has been cultivated for millennia.
Malting barley is usually lower protein which leads to more uniform germination, with shorter steeping.
The lower protein content also reduces the haze that results from precipitated protein.
Two-row barley generally has a lower protein content compared to six-row.
-A single mutation is responsible for the difference between two-row and six-row barley.
-Two mutations of wild barley prevent the spike from shattering.
Traditionally barley was classified by morphological differences and were considered to be different species.
-Two-rowed barley with shattering spikes (wild barley) is classified as HordeumspontaneumK.Koch.
-Two-rowed barley with non-shattering spikes is classified as H. distichum L.
-Six-rowed barley with non-shattering spikes as H. vulgare L. (or H. hexastichum L.).
-Six-rowed with shattering spikes as H. agriocrithonÅberg.
Recent cytological and molecular evidence has led most recent classifications to consider all forms as a single species, H. vulgare L.
Maris Otter is a 2-row, "winter" variety bred by researchers at Cambridge and introduced in 1966 possessing low nitrogen (protein) and superior malting characteristics.
It is a cross of Proctor and Pioneer.
During drying and or kilning, some enzymes become denatured. Generally darker grains are roasted longer and at higher temperatures and thus have less active enzymes then pale malt. Crystal malt is kilned without drying which denatures all enzymes.
Importantly, during the drying phase, most lipase and lipoxygenase enzymes are destroyed. These enzymes are implicated in the formation of off flavors in beer as it ages. Kilning also roasts the grain. During the roasting process a glorious reaction called the Maillard reaction occurs.
Modification: the degree of breakdown of the starch-protein matrix during the malting, drying, and kilning process
A general reaction between an amino acid and a reducing sugar and contributes to the color and flavor of browned bread, chocolate, seared meat, caramel and deep fried death.
(dark color and toasty aroma)
isobutyraldehyde (wet cereal/straw)
The modern history of enzymes began in 1833 when French chemists described the isolation of an amylase complex from germinating barley and named it diastase.
Sugar enzymology I
breaking down more chains of stuff
Generally only needed when using >25% unmalted wheat or barley, corn, or rye
β-1,4 glycosidic linkage
Protein rest: lower temperatures (122ºF (50ºC) ) yield shorter peptides and single amino acids (free amino nitrogen aka FAN) which aren’t as good for head retention.
Temperatures closer to 133ºF (55ºC) leave longer peptide chains and more available amino acids for yeast.
Generally only needed when using minimally modified malt or a lot (>25%) of adjuncts
Some recent research suggests that most proteases are destroyed during kilning and that there is no significant reduction in the molecular weight spectrum of the mash.
Enzyme activity is affected mainly by temperature, but also pH, presence of metals or cofactors, substrate concentration, viscosity, etc
The thicker the mash, the more active the enzymes.
Maximum rate possible
reaction rate ([producet]/second)
Soft Resins 13%
Alpha Acids 8%Beta Acids 4%Other Soft Resins 1%
Hard Resins 2%Essential Oils 1%
Hydrocarbons 0.75%Oxidation Products 0.2%Sulphur containing compounds 0.05%
Vegative Matter 84%
D-form amino acids tend to taste sweet,
L-form amino acids are generally tasteless.
Proteins use L-amino acids
Most sugars we digest and incorporate are D
Hop compounds act as ionophores that exchange protons for cellular divalent cations. This decreases the intracellular pH and dissipates the transmembrane proton gradient (ΔpH) and the proton motive force (pmf). Bacteria have evolved a number of ways to resist killing by hops.
HorA (a) and probably also by a pmf-dependent transporter (b)
overexpressed H+-ATPase increases the pumping of protons released from the hop compounds (c) Galactosylated glycerol teichoic acid in the cell wall and a changed lipid composition of the cytoplasmic membrane of beer spoilage lactic acid bacteria may increase the barrier to hop compounds.
-Single-celled fungus from the phylum Ascomycota
-One of the most well characterized organisms
-Genome sequenced in 1996
-Capable of sexual and asexual reproduction
-Found in wild on fruit surfaces
Lager yeast is more complex. First called S. carlsbergensis or S. pastorianus, then considered to be S. cerevisiae, are now recognized as a hybrid of S. cerevisiae and S. bayanus
Gene expression in lag phase and early log phase
Brejning et al. J Appl Microbiol. 2005.
Fermentation profiles with various sugar supplements
Piddocke et al. Applied Microbiology and Biotechnology 2009
Stationary phase is more complex than it seems
Extending healthy life span--from yeast to humans.
Fontana L, Partridge L, Longo VD.
Science. 2010 Apr 16;328(5976):321-6. Review.
Insulin/IGF-I and related signaling pathways regulate aging in nondividing cells: from yeast to the mammalian brain.
Parrella E, Longo VD.
ScientificWorldJournal. 2010 Jan 21;10:161-77. Review.
Genetic links between diet and lifespan: shared mechanisms from yeast to humans.
Bishop NA, Guarente L.
Nat Rev Genet. 2007 Nov;8(11):835-44. Review.
Gray et al. Microbiology and Molecular Biology Reviews. 2004.
Yeast can suppress respiration in the presence of glucose and oxygen
yeast convert acetolactic acid into valine instead of diacetyl (butanedione) and converts any butanedione into butanediol which is neutral as far as beer flavoring
Lagering: beer stored at 34-40 F for a few weeks. levels of diacetyl, acetaldehyde and sulfur compounds decrease.
The dynamics of the Saccharomyces carlsbergensis brewing yeast transcriptome during a production-scale lager beer fermentation.
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FEMS Yeast Res. 2002 Dec;2(4):563-73.
Two-dimensional gel analysis of the proteome of lager brewing yeasts.
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Yeast. 2000 Apr;16(6):511-22.
nd Not determined, SMM S-methyl methionine, and 3-MTP 3-methylthiopropionaldehyde
aUnless stated otherwise, odor threshold values were determined in beer.
bIn alcohol-free beer
Landaud et al. App. Microbiol. Biotechnol. 2008
Breeding an Amylolytic Yeast Strain for Alcoholic Beverage Production.
Cheng MC, Chang RC, Dent DF, Hsieh PC.
Appl Biochem Biotechnol. 2010 Sep 5. [Epub ahead of print]
The potential of genetic engineering for improving brewing, wine-making and baking yeasts.
Appl Microbiol Biotechnol. 2001 Sep;56(5-6):577-88. Review.
Improvement of Saccharomyces yeast strains used in brewing, wine making and baking.
Donalies UE, Nguyen HT, Stahl U, Nevoigt E.
Adv Biochem Eng Biotechnol. 2008;111:67-98. Review.
Genetic improvement of brewer's yeast: current state, perspectives and limits.
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Multiobjective optimization and multivariable control of the beer fermentation process with the use of evolutionary algorithms.
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Tumor cell energy metabolism and its common features with yeast metabolism.
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Neoplasma. 2008;55(5):387-93. Review.
Brewer's/baker's yeast (Saccharomyces cerevisiae) and preventive medicine: Part II.
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National Institutes of Health digital archive of biomedical and life sciences journal literature
Site of Brew Your Own magazine
Site of UC-Davis Anheuser-Busch Endowed Professor of Brewing Science Charles Bamforth
Rensselaer Polytechnic Institute brewing class
High performance liquid chromatograph (HPLC)
Gas chromatograph (GC)
Electrospray ionization m
mass spectrometer (ESI-MS)