Beer is a popular beverage produced by the fermentation of hopped malt extracted from barley and other grains. Some compounds (flavors) have a positive effect on aroma (attributes) and some have a negative effect (defects). This presentation will focus on a new method that enables the investigation and characterization of flavors and defects of beer in one analysis using HS trap/GC/MS.
Classically, this analysis is performed on four separate detectors. This new method employs one detector (MS) to provide these solutions required for the production and the testing of beer. The outcome is a more cost effective, accurate means to ensure the validity and the quality control of their product. Other benefits include enhanced productivity, attaining more information from a single analysis, and requiring less bench space.
The following experiments and results will be discussed.
• Quantitation of dimethyl sulfide (DMS), 2,3-butanedione (diacetyl), 2,3-pentandione and t,2-nonenal • Characterization of several types of beers • Fermentation profiling • Analysis of raw materials • Aging studies
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Determining Flavors and “Defects” in Beer by Headspace Trap/Gas
Chromatography/Mass Spectrometry
Andrew Tipler, Chromatography R&D ManagerLee Marotta, Field Application Scientist
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This presentation will describe a system that provides an almost comprehensive analysis of flavor compounds and defects in beer Theory Design and operation Beer Application
The system comprises the following components: A headspace trap sampling system A gas chromatograph A mass spectrometer
Flavor Compounds – MS (characterization) Alcohols Ketones Esters Acids Turpenes
Fermentation Markers Diacetyl
Replacing Multiple Systems with One …
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The authors would like to thank Bill Yawney of the LongTrail Brewery, Vermont, for his advice, inspiration and some of the analytical data used in this presentation
Headspace Instrumentation – Theory, Design and Operating Principles
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Principles Behind Headspace Sampling
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Besides actually making beer, much of the fun is associated with drinking it!
It’s nutritious, it makes the world easier to live in and it tastes good.
Taste is obviously subjective but we beer connoisseurs generally consider the following when drinking a fine beer: Don’t drink out of the bottle Don’t cool the beer to Arctic temperatures Use an appropriately shaped glass Don’t fill the glass completely
Tasting Beer
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Besides actually making beer (of course), much of the fun is associated with drinking it!
It’s nutritious, it makes the world easier to live in and it tastes good.
Taste is obviously subjective, but beer connoisseurs will generally consider the following when drinking a fine beer: Don’t drink out of the bottle Don’t cool the beer to Arctic temperatures Use an appropriately shaped glass Don’t fill the glass completely These are all done to ensure that the beer
aroma is involved in the tasting process (beer aroma, or ‘nose’ as it’s called, is an important part of the formal beer-judging process)
Tasting Beer
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Headspace sampling is a bit like smelling the aroma
Step 1 – put beer sample into a vial and seal it
Step 2 – heat the vial for a period of time at a constant temperature
Step 3 – extract some of the vapor and analyze it by gas chromatography
Headspace Sampling
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During the equilibration step, molecules distribute themselves according to their partition coefficients
Molecules with low partition coefficients favor the vapor (headspace) phase whereas molecules with high partition coefficients favor the liquid (sample) phase
Partition coefficients are reduced as the temperature is increased
At equilibrium, the concentration in the headspace phase is proportional to the original concentration in the sample
Determining the composition of the headspace phase enables the composition of the sample to be established.
Theory
Liquid Sample
Compound
K=Cl/Cv
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Key Components in the PerkinElmer Headspace System
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Since polar compounds in water (or beer) have very high partition coefficients – often less than 0.5% of the compound in the sample may pass into the headspace.
With headspace without the trap, only a small fraction of the total headspace vapor will enter the column
The headspace trap technique can enhance detection limits by 100 times by withdrawing the entire HS volume and enabling several injections from same vial to be focused on trap
Characterizes beer by Providing component identity – WHAT IS IT? Qualitative information Providing relative component ratio information Providing concentration (quantitative) information – How much?
Enables the investigation of other beers – What makes my neighbors beer so very delicious?