Clarification and Clarity of Cask Ales

Clarifica(on and Colloidal Stabiliza(on of Cask Ales Ian L Ward
Brewers Supply Group
Nov 2011
Cask Ale • 
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Naturally Carbonated Cellar Temperature Subtle, Nuanced Aroma and Flavor Cloudy? Cask Ale should be clear! •  Cask Ale should be clear bright and appealing –  Cask Ales served in England oDen rejected if not sparkling bright •  With aGen(on to process and detail cask ales can be bright as well as delicious! What causes beer haze? BIOLOGICAL PARTICLES
Brewers Yeast
Wild Yeast
Bacteria
NON BIOLOGICAL PARTICLES
(NMP)
Particulate matter
Protein – Polyphenol complex
Carbohydrate e.g. Starch
Calcium oxalate
Lipids
CLARIFICATION & PACKAGING
Brewers Yeast
Wild Yeast
Bacteria
Calcium oxalate
Protein – Polyphenol complex
Carbohydrate
Addition Related
Brewing Process Control Measure
Turbidity Input
Dust from malt handling
Malt
Husk material
Mash tun
Pneumatic or
mechanical
grain cleaning
Protein
Polyphenols
Lauter tun
Filtration of wort through husk
Hop Particles
Trub
Wort kettle
Coagulation of protein
poly phenol to give trub
Whirlpool
Yeast
Precipitation of cold break
Precipitation of protein
polyphenol complexes
Fermenter
Storage / maturation
Filtration
PACKAGING
Separation of trub & Hops
Settlement of cold
break
Application of Yeast Flocculent
Final Filtration
Control of haze inputs Since no final filtra(on haze inputs must be controlled at every opportunity –  Biological inputs controlled by good hygiene –  Wild yeast and bacteria very difficult to fine by standard fining techniques –  Good brew house and cellar hygiene a given –  Casks to be properly cleaned & inspected. Selec(on of Raw Materials •  Malt quality is the first step in controlling the protein load presented the the clarifica(on system •  Ideally malt should be < 10% protein –  UK brewers seek less than 9.5% –  Since Cask Ales are oDen low in alcohol flavorsome varie(es such as Maris OGer or Golden Promise find favor –  Malt should be well modified Milling & Mashing •  Proper control of mill se]ngs to control husk and ensure a proper mash tun / lauter bed •  Cask Ale can be made using isothermal mash tuns, lauter tun or mash filter systems provided that system gives good wort clarity –  Avoid flooded bed or channeling, excessive raking, or over extrac(on Brewing
Process
Maturation
Fermentation
Whirlpool
Kettle Cast
Kettle Up
Last Runnings
First Runnings
Mash In
Polyphenol Concentration mg/l
Changes in Total Polyphenol Levels
During the Brewing Process
Proline Residue and Polyphenol Interac(on Polyphenol- Protein Complex
Polyphenol monomer
Proline residue HA protein
Control of Wort Proteins – Good vigorous boil •  Although important for a host of reasons –  Hop isomeriza(on –  Flavor development –  DMS reduc(on –  Steriliza(on etc… •  Protein coagula(on during boil is cri(cal to reduce to par(culate load in green beer. In Cask ale no filtra(on •  Brewer cannot rely on a final filtra(on to correct deficiencies •  Clarity is achieved by gravity! v = 2(ρp-­‐ρf)r2g 9η V = velocity of settlement
ρp = density of the particles
ρf = density of the fluid
r = radius of the particle
g = acceleration due to gravity
η = viscosity of the fluid
Brewing Process Control Measure
Turbidity Input
Dust from malt handling
Malt
Husk material
Mash tun
Pneumatic or
mechanical
grain cleaning
Protein
Polyphenols
Lauter tun
Filtration of wort through husk
Hop Particles
Trub
Wort kettle
Coagulation of protein
poly phenol to give trub
Whirlpool
Yeast
Precipitation of cold break
Precipitation of protein
polyphenol complexes
Fermenter
Storage / maturation
Cask Racking
Separation of trub & hops
Settlement of cold
break
Application of Yeast Flocculent
Control of Wort Proteins – KeGle Finings •  Tradi(onally Irish Moss ~ Chondrus crispus •  Raw seaweed added to the keGle to provide protein coagula(on •  Ac(ve ingredient K-­‐carrageenan •  Modern materials derived from Euchema coGonii Ac(on of KeGle Finings •  K-­‐carrageenan is a nega(vely charged carbohydrate polymer that binds to posi(vely charged wort proteins •  Op(mally keGle fined worts present beer fining systems a manageable par(culate load •  Several product formats available from powders granules to tablets •  Typically added 10-­‐20 minutes to end of keGle boil Kettle Fining and Protein Levels
Control 10ppm
20ppm
30ppm
40ppm
50ppm
Fermenta(on & Condi(oning •  pH drops reducing solubility of proteins •  Protein-­‐polyphenols react to form large insoluble proteins •  Yeast flocculates at end of fermenta(on –  Ensure selec(on of good floccula(ve yeast –  Ensure good cold condi(oning Brewing Process Control Measure
Turbidity Input
Dust from malt handling
Malt
Husk material
Mash tun
Pneumatic or
mechanical
grain cleaning
Protein
Polyphenols
Lauter tun
Filtration of wort through husk
Hop Particles
Trub
Wort kettle
Coagulation of protein
poly phenol to give trub
Whirlpool
Yeast
Precipitation of cold break
Precipitation of protein
polyphenol complexes
Fermenter
Storage / maturation
Cask Racking
Separation of trub & hops
Settlement of cold
break
Application of Yeast Flocculent
Tradi(onal Finings ~ Isinglass Isinglass Mechanism of Interaction
1. Negatively
charged yeast cells
and neutral NMPs.
2. Positively
charged isinglass
interacts with
negatively
charged yeast
cells to form flocs
3. Flocs settle
rapidly as
described by
Stokes Law,
entrapping NMP s
Isinglass Mechanism of Interaction
1. In practice as well as
yeast cells, dead cells and
protein are present as
uncharged or +ve species
2. Auxiliary finings are
strongly –ve polymers
which adhere to the +ve
protein and dead cells
rendering everything in
suspension -ve
3. Isinglass reaction is
now possible by
adsorption
4. Complete clarification
is observed fit for cask
beer
Electron Micrograph of Isinglass & Yeast Rules for Isinglass Use • 
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Once in liquid for keep cold! <10degC Use liquid isinglass within 3 weeks Isinglass must be well mixed into the beer Make sure the beer is cold when fining –  Solubility of beer proteins propor(onal to temperature –  Isinglass only removes insoluble material –  Allow beer to warm to serving temperature –  Any residual protein is likely to dissolve rather than precipitate Applica(on of Finings •  Auxiliary finings added to the cask or matura(on tank prior to beer (typically 0.25 pt per firkin) •  Beer filled into cask •  Isinglass solu(on (0.3% w/v, typically 1 pint per firkin) •  Isinglass not mixed with Auxiliary Finings •  Bung hammered in Alterna(ves to Isinglass •  Isinglass non-­‐vegetarian •  Although overblown, concern over fish allergies •  Bovine collagen heavily researched but even less desirable than isinglass •  Colloidal Silica holding promise –  Combined fining and stabiliza(on –  Does not readily reseGle mul(ple (mes Effect of Dry Hopping •  Wonderful for aroma! •  Terrible for clarity! •  Extra polyphenol loading interacts with beer proteins to yield a haze •  Hop Aroma products •  Use of silica / isinglass New Development – Fastcask™ •  Beer seGled at the brewery •  Yeast immobilized onto gel beads are added to the cask like finings •  Yeast provides for carbona(on as normal •  Due to size and density gel beads seGle very quickly •  Cask Ale can be served bright immediately •  Beer can be reseGled mul(ple (mes