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
–
–
–
–
–
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
5
WHAT IS FRESHNESS?
6
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
8
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
9
Where Should You focus?
• Across the entire system
Brewery
Brewhouse
Wholesaler
Fermentation
Retailer
Finishing
Packaging
We will first look at the brewing process
10
BREWHOUSE
11
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
13
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
14
FERMENTATION
15
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
20
The Brewing Process
- factors that are important for freshness Brewhouse
• Oxygen
• Heat
Fermentation
• Yeast
– SO2
Finishing
Packaging
• Oxygen
• Oxygen
• Metal ions
21
PRACTICAL STEPS TO FRESHNESS
IMPROVEMENT
22
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
23
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
24
Brewhouse Freshness Best Practices
- Lautering Not
exposing the
grain bed
Minimal
Foam
Side mash
entry
or
Bottom
mash entry
Minimize exposure to air
25
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
26
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
27
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
28
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
30
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
31
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
32
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
34
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
9
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
35
MAKING FRESHNESS DECISIONS
36
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
37
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?
38
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
39
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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