9/24/2009
- Want to do project on light struck beer flavor compound formation. Want to use second life.
[You might get some good hits from a SciFinder search of "beer" JCB]
[First create an account at http://seconlife.com and download the free software on your laptop JCB]

10/01/2009

- Created an account on secondlife.[What is your avatar's name? JCB]
- Checked out a few books on beer processing from the library.
- Searched Web of Knowledge for "beer" and "hops".
- Beer Search DOI
- Did a wikipedia search for "Hops".
- Wikipedia Hops

10/15/2009
- Avatar's name on secondlife is "alxb Davidov" [OK just friended you - I'm Horace Moody JCB]
- Will focus paper on the formation and detection of different beer flavor compounds.
- Found three new papers using SciFinder. One on Carbonyl flavor compounds in beer. One on detection of 3-methyl-2-butene-1-thiol(MBT) using spectrophotometric methods. One on MBT formation and using Headspace SPME GC-MS to analyze the formation.
- Found ChemSpider site for MBT

10/29/2009

Rough Outline of Research Paper:

1) Introduction
  • Brief Beer Processing Intro.
    • Brewing history, brewing technology
    • Different types of beer (different desired flavors)
  • Intro to Flavor Compounds in Beer
  • Intro to Methods of Detection (GC/MS, HPLC, etc.)

2) Chemical Rxns in Beer/Compounds Formed
  • Production Reactions
  • Storage Reactions
    • Short term and long term
  • Flavor compounds produced during these stages.
    • The Good
    • The Bad
    • The Ugly
3) Effects of different flavor compounds
  • What flavors do different compounds actually produce?
  • Which ones are desired? How much?
  • Which ones are negative? How much?
  • Characteristic flavors vs. off flavors.
4) Detection of different compounds.
  • Methods of detection.
    • GC/MS
    • Spectrophotometric
    • HPLC
  • Detection requirements
    • Limits of detection (human vs. instrumental)
    • Preparation of samples.
  • Comparison of different methods
    • Which is better for different types of compounds.
  • Examples of work done on beer flavor compounds.
5) Conclusion


Based on previous outline, is this getting specific enough or too specific?


Secondlife Part

- I am thinking of building a quiz game in Second Life. Make it interactive with the possibility of using the act of choosing different beers(or drinking them if possible?) and having them correspond to note cards. The quiz would be based off of these notecards.

[Full Marks JCB]

Link to Summary Article Summary Article

Article Summary

Spectrophotometric Method for Exploring 3-Methyl-2-butene-1-thiol (MBT) Formation in Lager

Abstract
  • Riboflavin dissapearance in beer at 445 nm linked to light-struck character
  • Beer was exposed to light and measured catechin, epicatechin, or tryptophol.
  • Spectrophotometric method used to measure this change.

Introduction
  • Light struck flavor is very displeasing to drinkers of beer.
  • Flavor and aroma caused by MBT
  • Isohumulones in beer react with sulfur compounds to form MBT.
  • Isohumulones do not absorb in the correct wavelength range for MBT formation study.
  • Riboflavin does. Also MBT does not form without Riboflavin present.
  • MBT has low flavor threshold and low concentration in beer. Challenge.
  • GC/MS can be used to analyze but it is expensive and time consuming.
  • Objective of study was to create simpler and cheaper method of detection.
  • Concluded that spectrophotometric measurement of ribovlavin was valid for detecing MBT.

Materials and Methods
  • Catechin, epicatechin, and tryptophol from Sigma-Aldrich.
  • Lager was from Foster's Australia.
  • Model beer prepared using citrate buffer, riboflavin, isohumulones, ethanol, and cysteine.
  • Samples were exposed to light of intensity 526, 3580, 4580 1x.
  • Riboflavin concentration determined using Beckman DU640 UV-Vis spectrophotometer at 445nm.
  • Sensory analysis performed by Carlton & United.
  • MBT was synthesized by dissolving Thiourea in 18% HCL, Prenol was added, stirred for 30 min. Solution heated to boiling and stirred overnight at 60C. Solution was made alkaline with KOH 30%w/w. Refluxed for 2 hr. Solution cooled and n-pentane was added. The MBT solution was stored as 10mg/L aqueous solution at -20C.

Results
  • Riboflavin absorbance peaks at 373 and 445 nm.
  • Model beer without riboflavin did not absorb here.
  • Riboflavin excited to singlet state, transitions to triplet.
  • Exposure of beer to light gave loss of color and development of light struck character.
  • The polyphenols that were added could prevent light struck character formation for >1hr.
  • Rate of riboflavin loss determined.
  • When isohumulones were added cloudiness occured after 40min.
  • Bubbling oxygen through the samples returned to normal color. Suggests light struck riboflavin is oxidized back to its original state or a derivitave thereof.
  • Addition of acorbic acid, a well known quencher and antioxidant of riboflavin, showed the ability to reduce light struck character.

11/08/2009


Searched: "Beer Flavor Compounds"
-Bitter Compounds in beer(alpha-acids) Bitter Compounds
-Volatile Compounds in "Low-Malt" Beer Low-Malt Volatiles
-Aging Characteritics of Beer Beer Aging
-Flavor Active Esters Esters
-Polyfunctional Thiols in Beer Thiols


11/09/2009

Chemical Properties Assignment

FurFural - Carbonyl Compounds in Beer Article
[Full Marks JCB]
-Boiling Point-
161-162dC Food/Ag. Org
162dC
162dC
323dF=161.7dC NIOSH
161.7dC

-Melting Point-
-38.8dC Journal of Chemical Engineering Science, 6, 1956/1957, 116-118.
-36dC NIOSH
-36dC
-38.1dC CRC Handbook of Chemistry and Physics
-38dC

-Flash Point-
60dC
60dC
140dF = 60C NIOSH
60dC Food/Ag. Org
58.3dC ChemSpider Predicted

-Specific Gravity-
1.159g/cm^3
1.16 g/mL 25dC
1.16g/cm^3 NIOSH
1.153-1.162g/cm^3 Food/Ag. Org
1.1594g/cm^3 CRC Handbook of Chemistry and Physics

-Refractive Index-
1.515 ChemSpider Predicted
1.51612
1.5246 (589nm)JACS
1.521-1.529 Food/Ag. Org
1.5261 (589nm) CRC Handbook of Chemistry and Physics

11/10/2009

Searched SciFinder: "3-methylbut-2-ene-1-thiol"
-Photoxidation of Beer Beer Bittering
-MBT in Wines (Detection Method Related to Beer) Wines
-Odor Active Compounds in Hopped/Un-Hopped Beer Odor
-Stale Beer Odorant Stale Beer
-Coffee Headspace Analysis for MBT Similar Techniques
-SPME Method Determining Sulfur Compounds in Beer SPME

11/19/2009

Searched References from Low-Malt Volatiles
-Aroma compounds in beer SPME Aroma SPME
-Aldehydes in Beer GC-MS Aldehydes GC-MS
-Lightstruck BeerPhotoxidative Degradation
-Beer Volatiles DetectionSPME GC-MS
-Headspace Single Drop ME BeerSingle Drop ME

Searched References from Bitter Compounds
-MBT FormationKinetics of MBT

Fermentation
-Ester FormationEsters