123rd MBAA Anniversary Convention

Fresh Beer, Fresh Ideas

Alastair PringlePringle –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

3

This talk will focus on flavor stability

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 • Wide freshness variation – confuses the customer

• Narrow range – customer gets a consistent product

5

Fre

quen

cy

Stale Fresh

Fre

quen

cy

Stale Fresh

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

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Changes in Beer • Freshness begins to decline once beer is

packaged

• The decline is accelerated by increased temperature

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4

5

6

7

8

9

0 100 200 300Days

80oF

70oF

36oF

Less

Fre

sh

Why Does Beer Lose Freshness?

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Staling is the sum of many flavor changes:

- no single compound or mechanism is responsible

- there is no single solution

Inte

nsi

ty

Time

Where Should You focus?

• Across the entire system

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Brewery Wholesaler Retailer

Brewhouse Fermentation Finishing Packaging

We will first look at the brewing process

BREWHOUSE

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First, a Word about Carbonyls

• A class of compounds that contain a C=O group

C=O

• 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

A

B

Brewhouse Chemistry - Mashing and Lautering -

13

Unsat. Fatty Acids

Carbonyls

Lipase

Polyphenols

Tannins

O2

Lipoxygenase

Malt polyphenolsMalt LipidsMalt Protein

Amino Acids

Protease

Oxygen is important in carbonyl production

Brewhouse Chemistry- Boiling -

14

Polyphenols

Carbonyls

O2

Iso-alpha acids

Extraction

Isomerization

Tannins +

Protein Carbonyl-protein

Wort

protein

From

Mashing

Maillard

Products

Unsat. Fatty Acids

Heat

Amino acids Hops Sugar

Copper

Vessels

& coils

Oxygen and heat drive complex reactions

Malt

Tannins

FERMENTATION

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Fermentation Chemistry

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Carbonyls

Alcohols Protein–

carbonyl

SO2

SO2–

carbonyl

Sulfate

H+

Yeast

Ethanol

Sugars

SO2

SO2 is an important anti-oxidant, especially in lagers

Carbonyls become bound to protein and SO2

Iron

Yeast

Iron

Uptake

Autolysis

FINISHING AND PACKAGING

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Finishing and Packaging Chemistry

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Iron

Reactive Oxygen Species

O2- superoxide anion

HOO- perhydroxyl radical

H2O2 hydrogen peroxide

HO. hydroxyl radical

OxygenFilter medium

Chemistry in the Package- reactions involving oxygen-

Oxygen

Reactive Oxygen Species

Finished

Beer

Package

Iron &

Copper

Sulfur Dioxide

Iso-alpha acids

Sulfate

Sweet, fruity• e.g. Ethyl isovalerate

Side chain

PolyphenolsHarsh, astringent• tannins

+

Others reactions – oxidation of ethanol and higher alcohols

Ethanol

Diagram courtesy of Grace Darex Packaging Technologies

ingressD.O.

Chemistry in the Package-reactions independent of oxygen-

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SO2– carbonyl

Protein – carbonyl

Carbonyl +

Maillard Products +

Paper, cardboard

• e.g. Trans-2-nonenal

Solvent

• e.g. furfuryl ethyl ether

SO2

Other reactions

– esterification, etherification, glycoside hydrolysis, & ester hydrolysis

Ethanol

These compounds, which originated in the brewhouse,

result in stale flavors in the package

The Brewing Process -factors that are important for freshness-

• Yeast

– SO2

– O2 uptake

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Brewhouse Fermentation Finishing Packaging

• Oxygen

• Metal ions

• Oxygen

• Heat

• Oxygen

PRACTICAL STEPS TO FRESHNESS IMPROVEMENT

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How can Freshness be improved?

• Maximal freshness can only be achieved by making improvements across the entire production chain

– Chain is as good as its weakest link

– Recommend that you do not only focus on one area

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Brewery Wholesaler Retailer

Brewhouse Freshness Best PracticesMashing

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Bottom

entry

Fore

masher

Course

grind Malt

No scorching or build-up No votex upon emptying

Water Effective mixing that minimizes foam and

creates no vortex

Pump seals maintained to

avoid air pick-up

Minimize exposure to air

Brewhouse Freshness Best Practices- Lautering -

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Bottom

mash entry

Side mash

entry

Minimal

Foam

Not exposing the

grain bed

or

Minimize exposure to air

Brewhouse Freshness Best Practices– Boiling -

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Gentle fill

minimizing foam

Avoid extended boil time

Efficient heat transfer – minimal scorching

No vortex during emptying Pump seals

maintained to avoid air pick-up

Avoid boil temperatures above 212 F

Minimize air and heat

Vigorous boil

Brewhouse Freshness Best Practices- Whirlpool-

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Tangential flow

Minimal foam on wort surface

Pump seals maintained to

avoid air pick-up

Gentle wortflow

Avoid excess time

Minimize air and heat exposure

Fermentation Best Practices

• Increase SO2 levels in lagers

– SO2 is an antioxidant

– below level requiring labeling

• Minimize yeast autolysis

– Can release iron into beer.

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Fermentor

Yeast

Maturation

Increase SO2 Reduce autolysis

Lower ferm. temp X

Lower aeration rate X

Lower pitch rate X

Increase yeast food X X

Lower maturation temp. X

Reduce maturation time X

Finishing Best Practices

29

De-oxygenate adjustment water

Filter Beer

Tank

Water Filter

Gas with CO2

before filling

Use low iron D.E.

Chiller

Buffer

Chill-

proofer

Maintain to avoid oxygen

pick up

Seals maintained to avoid air pick-up

De-oxygenate water

Minimize air and iron pickup

PACKAGING

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Packaging Freshness Best Practices

• Minimize oxygen – Finished beer D.O. should be low (50 ppb)

– Bottles • Evacation

• 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 high levels – Too inaccurate to be used for driving

down oxygen levels

• Dissolved oxygen – better – Pierce package and run beer

through a D.O. meter. – Detects beer D.O. 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

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Package Type Source of oxygen ingress Improve freshness through:

Glass Bottle • Crown • Barrier crown - better• Absorbing crown – best

Plastic Bottle • Closure

• Bottle

• Barrier crown – better • Absorbing crown – best

• Oxygen barrier – nylon • Absorbing technology – e.g. Co

Can • Minimal ingress

Diagram courtesy of Grace Darex Packaging Technologies

DISTRIBUTION

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4

5

6

7

8

9

0 100 200 300

Days

Distribution Chain Control- It all about Time and Temperature -

• Higher temperature leads to a rapid loss of freshness – 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

80oF 70oF

Keeping beer cool and for shorter times

means beer is consumed fresher

– local production and distribution helps

Less

Fre

sh

MAKING FRESHNESS DECISIONS

36Photo courtesy of PureMalt

Tools to Assess the Process

• Process assessment

– Visual:

• Vortexing

• Excessive foam in brewery vessels

• Scorching on heat exchange surfaces

– Measurement

• Excess 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? 38

Beer Shelf-Life Determination

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4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

0 50 100 150 200 250 300

Days

70 F

32 F

Less

Fre

sh

Shelf-life is the time before the beer tastes unacceptably

different from fresh beer

X

Summary

• 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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Brewery Wholesaler Retailer