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Transcript of Bottle conditioning
Bottle Conditioning:Yeast Refermentation
Neva ParkerHead of Laboratory Operations
White Labs, Inc.
Outline
• Basics of bottle-conditioning– Overview of the biology – Methods– Advantages & Challenges
• The Refermentation– Yeast strain selection– Yeast quality & yeast health– Dosing rate
Basics of Bottle Conditioning
Yeast MetabolismHappens during fermentation & refermentation
EtOH & CO2
Basics of Bottle Conditioning
Fermented Beer + Sugar + Yeast (+ 2-3 weeks)
= Carbonated Beer
Basics of Bottle Conditioning
A quick note on CO2:
Dissolves in beer – more dissolves at lower temps
Measured as Volumes of CO2 - each Volume is basically ~2 g/L
Most labs use a pressure gauge & conversion chart to measure Volumes
Basics of Bottle Conditioning
Methods:
1. Krausening2. Partial forced-carbonation & bottle-condition3. Use clear/filtered beer, add back sugar, add new
yeast
Why Bottle-Condition?
Tradition
Special Products/Marketing
Stable Shelf-Life
Improved Sensory
Challenges to Bottle-Conditioning
Consistent carbonationEnvironmental (for yeast) – alcohol & pH levelsCan be more difficult & time-consumingTemperature to hold packagesTime & cost of holding inventoryPotential flavor impacts from second fermentationAppearance of sediment to consumers
The Refermentation: What you need to know
Yeast Strain Selection
Dry vs. Liquid – is there a difference? - In laboratory trials – performance is similar- Possible flavor impact, but its strain-dependant
Alcohol & pH tolerant yeast- California Ale Yeast or equivalent- Some neutral wine strains
The Refermentation: What you need to know
Yeast Strain SelectionFlocculation properties
- Settles well at the end of refermentation
The Refermentation: What you need to know
Yeast Strain SelectionFlocculation properties
- Sticks to bottom of package - Produces a fine sediment
The Refermentation: What you need to know
Yeast Strain SelectionSensory Contribution
The Refermentation: What you need to know
Yeast Strain SelectionSensory Contribution
Flavors:- Generally, not perceivable if using a neutral yeast
strain- Some esters & fusels will be produced as part of
the fermentation- Will help prevent oxidation and consume any
left-over diacetyl
The Refermentation: What you need to know
Yeast Strain SelectionSensory Contribution
Mouthfeel- Bottle-conditioned beer has been reported to
have a fluffier, longer-lasting head- By trained taste panel, described as being
smoother carbonation & more efferevescent
The Refermentation: What you need to know
Yeast Strain SelectionUsing Brettanomyces
- Produces CO2 as brewers yeast, can be dosed similarly
- Contributes flavor compounds but takes longer to develop
- Can metabolize larger sugars, so that should be taken into account
The Refermentation: What you need to know
Yeast QualityShould be fresh yeast (early generation, 3rd or less)
Poor viability = Poor CO2 productionCan also lead to autolysis & cell components leaking
into beer = yuck Contamination can lead to off-flavors in final package
The Refermentation: What you need to know
Yeast Dosing Rate
Typical beers range from 2.5-3.5 Volumes CO2
Recommended:500,000 cells/ml beer – 1 million cells/ml beer
SO….you need to do a CELL COUNT
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:
• Yeast cells are easily seen at 40X power.
• You may also notice trub in your viewing field that may stain.
• Yeast buds emerging from the mother cell are counted as separate cells if the bud is at least one-half the size of the mother.
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:
• Dead cells will stain dark blue• Cells that are clear or pale
blue in color are considered alive.
• Some budding cells will stain dark blue, but they are not dead! Buds are busy with growing metabolism and not extruding the dye.
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:Calculate your Cell Count:
Take the total # of cells you counted in the 25 squares 1,510Determine your dilution factor of your sample. 1:100 Volume in Hemacytometer chamber is 1/10,000 ml
Yeast cells/ml= Total cells in 25 squares x dilution factor x volume in hemacytometer chamber (1x10^4)
Example:1,510 x 100 x (1 x104) = 1.51 x109 or 1.51 billion cells/ml
The Refermentation: What you need to know
Yeast Dosing RateA quick refresher on cell counting:
Calculate your viability:
# of live cells ÷ total number of cells x 100% = viability %
Example: 7 dead cells total 1475 ÷ 1510 x 100% = 97.7% viable
You’ll want yeast to be as viable as possible – nothing below 90%
The Refermentation: What you need to know
Yeast Dosing Rate
Calculation:{(1x10^6 * 119,333)/2.41 x 10⁹} / 1000
= Liters of yeast slurry
Volume of wort in milliliters
Cell count of slurry (cells/ml)
Conversion factor for Liters
Desired pitch rate (cells/ml)
The Refermentation: What you need to know
Sugar – what kind and how much?
- Malt or DME- Corn sugar or table sugar- Various other sugars such as cane sugar,
honey, corn syrup, Belgian Candy sugar
The Refermentation: What you need to know
Sugar – what kind and how much?
- Typically 0.5lb-0.75lb to achieve 2.5-3.0 Volumes of CO2
- Bottle-Conditioning worksheet by John Mallet of Bell’s Brewing
Remember: the type and amount of sugar can influence the yeast fermentation
Successful Conditioning
Proper sugar additionProper yeast strainGood yeast quality and yeast healthProper dosing rateImplementation of a good quality control program
for bottled product