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Páginas: 5 (1132 palabras) Publicado: 14 de abril de 2011
3/31/2011

ACS Webinars™

We will start momentarily at 2pm ET

Download slides: http://acswebinars.org/bamforth2011

Contact ACS Webinars™at acswebinars@acs.org

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Help Shape the future of ACS Webinars!

Join the ACS Webinars Audience Advisory Panel! Learn more: www.acswebinars.org

Contact ACS Webinars™at acswebinars@acs.org

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3/31/2011

Have Questions?
Use theQuestions Box!

Or tweet us using #acswebinars
Download slides: http://acswebinars.org/bamforth2011

Contact ACS Webinars™at acswebinars@acs.org

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You could be the lucky winner!

One lucky winner will receive a signed, hardback copy of Charlie’s book, Beer is Proof God Loves Us: Reaching for the Soul of Beer and Brewing!

Contact ACS Webinars™at acswebinars@acs.org

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Do You Know a Hero of Chemistry? Nominate them now
At the 2011 ACS Fall National Meeting in Denver, we will be honoring Heroes of Chemistry for the vital role these industrial chemical scientists and their companies play in improving human welfare through successful commercial innovations and products. It presents an ideal opportunity to enhance the public image of the chemical andallied industries. Each year, Heroes of Chemistry are nominated by their own companies to recognize their talent, creativity, and innovation. More information can be found at www.acs.org/industry

American Chemical Society

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Upcoming ACS Webinars™
www.acswebinars.org/events

Tuesday, April 5, 2011

Successfully Working with Recruiters – Dos and Don’ts
Patrick Ropella, Ropella, and DonAlexander, Carlyle & Conlan

Thursday, April 7, 2011

Optimizing the Workplace Across Five Generations of Scientists
Tamara Erickson, author and trainer on how to build an innovative organization

Contact ACS Webinars™at acswebinars@acs.org

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3/31/2011

ACS WEBINARS™ March 31, 2011 Advanced Chemistry of Beer and Brewing

Charles Bamforth, UC Davis

Steve Carlo, Chemist,Homebrewer

Please submit your questions for the speaker via the Questions Panel in GoToWebinar

Download slides: http://acswebinars.org/bamforth2011

Contact ACS Webinars™at acswebinars@acs.org

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Advanced Chemistry of Beer and Brewing
Charlie Bamforth
March 31 2011

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3/31/2011

Quality of Beer Package Foam Gushing Clarity Color Flavor Stability Safety & wholesomeness Notmutually exclusive

Barley
malting

Malt
mashing boiling

Wort
fermentation

“Green Beer”

Beer
stabilization filtration

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Aspects of beer foam
Formation (nucleation, beading) Stability (head retention) Lacing (cling, adhesion) Texture, whiteness etc

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Drainage

Q= 2ρgqδ 3η where Q is flow rate η is viscosity of film liquid ρ is density q islength of Plateau border g is acceleration due to gravity δ is thickness of film

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Beer foam Physics
Disproportionation

Beer foam Physics
Disproportionation (continued) rt2 = ro2 - 4RTDS γ t Pθ where rt is the bubble radius at time t ro is bubble radius at the start R is the gas constant T is absolute temperature D is the gas diffusion coefficient S is the solubility ofthe gas γ is the surface tension P is atmospheric pressure θ is the film thickness between bubbles

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Foam
Positives polypeptide iso-α-acids Me 2+ N2 Negatives Lipid Detergents Ethanol

Which proteins?

-Discrete polypeptide hypothesis - Generalized amphipathic polypeptide hypothesis

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Some proposed foaming proteins Lipid Transfer Protein (LTP1) Frombarley Unchanged in malting and mashing Activated during boiling by denaturation

Protein Z (40kD protein) - from barley - attached to β-amylase

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Protein mixture Salt solution Octyl sepharose

Hydrophobic protein binds strongly

unbound water hydrophilic

glycol

→ increasingly hydrophobic

The generalized amphipathic polypeptide hypothesis

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