Transcript Background - Factors that Affect Beer Shelf Life

123rd MBAA Anniversary Convention
Fresh Beer, Fresh Ideas
MBAA – New England
January 2014
Alastair Pringle
Pringle –Scott LLC
Objective and Outline
• Objective
– Identify practical solutions for keeping beer as fresh as
possible.
• Outline
–
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–
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Background
What is freshness?
Reactions in brewhouse, fermentation, & finishing
Practical steps to freshness improvement
Making decisions on freshness
2
Background
- Factors that Affect Beer Shelf Life
• Microbiological spoilage
– Bacteria: lactic acid, diacetyl, H2S, etc
– Yeast: over-attenuation, over carbonation
–
• Physical stability
– Chill-haze
– Permanent haze
• Flavor stability
– Changes in flavor
This talk will focus on flavor stability
3
Background
- Why Worry About Flavor Stability?
• Customers want a consistent flavor
• They accept consistent flavor, even if it
includes off-flavors
– e.g. DMS, oxidation, light-struck
• They reject variable flavors
– Beer will not meet their expectations
– Do not like surprises
4
Freshness in the Marketplace
Frequency
• Wide freshness variation – confuses the customer
Fresh
Stale
Frequency
• Narrow range – customer gets a consistent product
Fresh
Stale
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WHAT IS FRESHNESS?
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Freshness
• Freshness is how close a
product is to when it was :
– Picked from the field
– Made in the bakery or
brewery
• Implied:
– Better taste
– Better nutrition
– No artificial preservatives
7
Changes in Beer
• Freshness begins to decline once beer is
packaged
• The decline is accelerated by increased
temperature
9
36oF
Less Fresh
8
7
6
70oF
5
80oF
4
0
100
200
Days
300
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Intensity
Why Does Beer Lose Freshness?
Time
Staling is the sum of many flavor changes:
- no single compound or mechanism is responsible
- there is no single solution
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Where Should You focus?
• Across the entire system
Brewery
Brewhouse
Wholesaler
Fermentation
Retailer
Finishing
Packaging
We will first look at the brewing process
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BREWHOUSE
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First, a Word about Carbonyls
• A class of compounds that contain a C=O group
A
C=O
B
• Include:
– long-chain unsaturated aldehydes.
• 1969 - trans-2-nonenal was shown to impart a stale,
cardboard, flavor when added to beer.
– other volatile carbonyls:
• ketones, esters
12
Brewhouse Chemistry
- Mashing and Lautering Malt Protein
Malt Lipids
Malt polyphenols
Lipase
Protease
Unsat. Fatty Acids
Polyphenols
O2
Lipoxygenase
Amino Acids
Carbonyls
Tannins
Oxygen is important in carbonyl production
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Brewhouse Chemistry
- Boiling Unsat. Fatty Acids
Hops
Polyphenols
From
Mashing
Sugar
Extraction
O2
Carbonyls
Wort
protein
Carbonyl-protein
Amino acids
Heat
Malt
Isomerization
Tannins
Tannins +
Protein
Iso-alpha acids
Vessels
& coils
Maillard
Products
Oxygen and heat drive complex reactions
Copper
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FERMENTATION
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Fermentation Chemistry
Carbonyls
Sulfate
Sugars
Iron
Uptake
Yeast
Yeast
Autolysis
SO2
H+
Alcohols
Protein–
carbonyl
SO2–
carbonyl
SO2
Ethanol
Iron
SO2 is an important anti-oxidant, especially in lagers
16
Carbonyls become bound to protein and SO2
FINISHING AND PACKAGING
17
Finishing and Packaging Chemistry
Filter medium
Oxygen
Iron
Reactive Oxygen Species
O2- superoxide anion
HOO- perhydroxyl radical
H2O2 hydrogen peroxide
HO. hydroxyl radical
18
Chemistry in the Package
- reactions involving oxygenFinished
Beer
Iron &
Copper
Package
D.O.
ingress
Oxygen
Reactive Oxygen Species
Sulfate
Sulfur Dioxide
Harsh, astringent
Polyphenols
Iso-alpha acids
• tannins
Side chain
Sweet, fruity
+ Ethanol
• e.g. Ethyl isovalerate
Others reactions – oxidation of ethanol and higher alcohols
Diagram courtesy of Grace Darex Packaging Technologies
Chemistry in the Package
-reactions independent of oxygenSO2– carbonyl
Carbonyl + SO2
Protein – carbonyl
Maillard Products
+ Ethanol
Paper, cardboard
• e.g. Trans-2-nonenal
Solvent
• e.g. furfuryl ethyl ether
Other reactions
– esterification, etherification, glycoside hydrolysis, & ester hydrolysis
These compounds, which developed in the brewhouse,
result in stale flavors in the package
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The Brewing Process
- factors that are important for freshness Brewhouse
• Oxygen
• Heat
Fermentation
• Yeast
– SO2
Finishing
Packaging
• Oxygen
• Oxygen
• Metal ions
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PRACTICAL STEPS TO FRESHNESS
IMPROVEMENT
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How can Freshness be improved?
Brewery
Wholesaler
Retailer
• Maximal freshness can only be achieved by
making improvements across the entire
production chain
– Chain is as good as its weakest link
– Do not only focus on one area
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Brewhouse Freshness Best Practices
Mashing
Effective mixing that
minimizes foam and
creates no vortex
Water
Course
grind
Malt
Fore
masher
Bottom
entry
No scorching or build-up
No votex upon
emptying
Pump seals
maintained to
avoid air pick-up
Minimize exposure to air
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Brewhouse Freshness Best Practices
- Lautering Not
exposing the
grain bed
Minimal
Foam
Side mash
entry
or
Bottom
mash entry
Minimize exposure to air
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Brewhouse Freshness Best Practices
– Boiling Vigorous boil
Avoid boil
temperatures
above 212 F
Avoid extended
boil time
Efficient heat transfer
– minimal scorching
Gentle fill
minimizing foam
No vortex
during emptying
Minimize air and heat
Pump seals
maintained to
avoid air pick-up
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Brewhouse Freshness Best Practices
- WhirlpoolMinimal foam on
wort surface
Tangential flow
Gentle wort
flow
Avoid excess
time
Pump seals
maintained to
avoid air pick-up
Minimize air and heat exposure
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Fermentation Best Practices
• Increase SO2 levels in lagers
Fermentor
Yeast
– SO2 is an antioxidant
– below level requiring labeling
• Minimize yeast autolysis
– Can release iron into beer.
Increase SO2
Maturation
Lower ferm. temp
X
Lower aeration rate
X
Lower pitch rate
X
Increase yeast food
X
Reduce autolysis
X
Lower maturation temp.
X
Reduce maturation time
X
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Finishing Best Practices
De-oxygenate
adjustment water
Water
Filter
Use low
iron D.E.
Buffer
Gas with CO2
before filling
Chillproofer
De-oxygenate
water
Chiller
Maintain to
avoid oxygen
pick up
Filter Beer
Tank
Seals maintained
to avoid air pick-up
Minimize air and iron pickup
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PACKAGING
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Packaging Freshness Best Practices
• Minimize oxygen
– Finished beer D.O. should be low (50 ppb or less)
– Bottles
• Evacuation
• CO2 flushing
• Proper adjustment of jetters
– Cans
• Use CO2 flushing
• Bubble breakers
• Under-cover gassing with CO2
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Measuring Package Oxygen
• Shake-out method – fair
– Better than not measuring oxygen
– Detects very high levels
– Too inaccurate to be used for driving
down oxygen levels
• Dissolved oxygen – better
– Pierce package and run beer
through a DO meter.
– Detects beer DO levels - but not
headspace oxygen
• Total package oxygen - best
– Oxygen in beer + headspace oxygen
– Semi-automatic
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Packaging Materials Best Practices
• Many more times the oxygen may
enter the package over its shelf-life as
is present immediately after packaging
Package Type
Source of oxygen ingress
Improve freshness through:
Glass Bottle
• Crown
• Barrier crown - better
• Absorbing crown – best
Plastic Bottle
• Closure
• Barrier crown – better
• Absorbing crown – best
• Bottle
• Oxygen barrier – nylon
• Absorbing technology – e.g. Co
Can
• Minimal ingress
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Diagram courtesy of Grace Darex Packaging Technologies
DISTRIBUTION
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Distribution Chain Control
- It all about Time and Temperature – 2 to 4 times more for every 18oF
(10oC)
– Beer stored at 80o F for 50 days
will be as fresh as beer stored at
70oF for 100 days
• Draft beer that is kept cold will
remain fresher than packaged
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40oF
8
Less Fresh
• Higher temperature leads to a
rapid loss of freshness
7
6
70oF
80oF
5
4
0
100
200
300
Days
Keeping beer cool and for shorter times
means beer is consumed fresher
– local production and distribution helps
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MAKING FRESHNESS DECISIONS
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Photo courtesy of PureMalt
Tools to Assess the Process
• Process assessment
– Visual:
• Vortexing
• Excessive foam in brewery vessels
• Scorching on heat exchange surfaces
– Measurement
• Excessive levels of dissolved oxygen
where you have clear liquid
– Lauter
– Wort receiver
– Kettle knock out
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Freshness Measurement
• Focus on a reliable measure related to the consumer
experience.
– Sensory is the best measure
– Avoid complex chemical analyses
– Measurement of radicals is mainly related to SO2 and or iron level
• Develop a Freshness Panel
– Train using in-house or outside expertise (FlavorActiv)
– Develop a scale: e.g. 1 to 10
• Use the panel to provide feedback on experiments and
process improvement efforts
– Does a process change improve freshness?
– Is the cost worth it?
– What is the shelf-life of a beer?
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Beer Shelf-Life Determination
9
8.5
8
7.5
7
6.5
6
5.5
5
4.5
4
Less Fresh
32 F
X
70 F
0
50
100
150
Days
200
250
300
Shelf-life is the time before the beer tastes unacceptably
different from fresh beer
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Summary
Brewery
Wholesaler
Retailer
• Freshness of beer in the marketplace is affected
by:
– Production methods from the brewhouse to the
finished package
– Storage conditions after the beer is packaged
• The freshness of beer that reaches the consumer
can be enhanced by systematically improving
each link in the chain as much as practically
possible
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The Art of Beer
Pringle-Scott.com
Questions?
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