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May 23
Mash off temperatures and astringency
by  Karl OckertNo presence information  on 5/23/2013 5:17 AM
Category: Sensory

​Q:  Most of books or people’s experience say a mash out temp should be about 76-77 C and not exceeding 80 C as polyphenols from grain husk may/must be dissolved which causes harsh taste in finished beer. By looking at decoction involved with a third of thick mash being heating up to boil for 5-40 min and pumped back to main mash for temperature adjustment I would be curious if boiling mash is acceptable in decoction but not in mash out, or it is ok to heat mash out temp above 80 C without further harshness?

 

Understood the pH being raised up upon run-off would accelerate polyphenols dissolving especially above 80 C; therefore to control sparging temp at 76-77 C is important.
 
A:  I have always wondered about that as well, I think there are some flavor differences between the beers that undergo decoction which probably does pick up some astringency, and those that use either single infusion or upward infusion mashing.  For US-Canadian lagers the harshness of the polyphneol pick up might not reflect well in the overall light flavor profile desired, for higher BU German beers (30-35 BU) the astringency may actually be part of the flavor profile.  Bitterness is a basic flavor and astringecy a mouthfeel but they are closely identified.  So I think it depends on the beer you are brewing, higher BU beers like German pils or IPA would probably not be adversley affected and perhaps even benifit from some added astringency while, lighter more delicate beers may suffer. 

 

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April 15
Brewhouse efficiency
by  Karl OckertNo presence information  on 4/15/2013 5:07 PM
Category: Calculations

Question

I am reading the brewhouse yield section of "a Handbook of Basic Brewing Calculations" and it states in order to know your brewhouse yield one piece of information needed is your brewhouse efficiency.  In the book it seems to me they guess at an efficiency but how does one calculate this number?

Answer

There are several efficiency calculations that are good to know from your brewhouse and every operation will be different depending on the process and materials used.  However the calculations for everyone are basically the same.  Let’s start with your mash yield which is a measurement of how much of the available starch you are converting and extracting from your mashing/lautering process per the amount of material used. 

Mash yield = Lbs of extract collected/lbs of malt (or other material) used. 

 
To get lbs of extract you need to accurately measure the volume of wort collected in your brewkettle (remember to multiply this number by 0.96 to account for thermal expansion) and the degrees Plato.  You can get the lbs extract/bbl from extract tables (MBAA Practical Handbook for the Specialty Brewer Table 5.2) or using the equation:
 
[(259 + deg P)deg P]/100
Normally the mash yields will be about 65% for malt, 75% for corn grits and 82% for syrups. This is a useful ratio used to calculate recipe grist weights.
 
Brewhouse efficiency is simply a ratio of what is recovered vs what was put in:   Lbs of extract collected divided by lbs of extract potential from the grist.  Although this efficiency ratio can be used at any step in the process, ie lauter to kettle, kettle to whirlpool tank, etc, ultimately brewhouse efficiency uses this ratio of outputs to inputs to measure just how efficiently the brewhouse has used the malt and other materials to produce a given volume of wort at a particular Original Extract (OE).  The higher the number, the less waste and loss.
 
To determine your brewhouse efficiency you will need to know how much extract is in each ingredient in the grist.  The malt house will supply a Certificate of Analysis and on the COA are numbers for % extract.  The listed extracts will normally include a “Fine Grind dry basis” which is the ultimate available amount of extract in complete extraction and does not include the weight of moisture.  The more practical “Coarse Extract as is” (moisture included) will give you a more realistic limit of how much your brewhouse could yield from the malt and is the number to use when making efficiency calculations.
 
The brewhouse efficiency then will be a ratio between what you could possibly expect to yield and what you actually yield.  To determine efficiency first multiply the coarse grind as is extract % by the weight of the grist  for each component, ie lbs pale male x X% coarse extract to get lbs extract possible from pale malt, same with crystal malt, wheat malt, etc. Total up the weight from each and this will give you total lbs of extract potential in the grist.
 
Your final yield from the brewhouse can be defined as the amount of extract actually recovered as cold wort in the fermenter compared to what you started with in the mash tun.  To get that number you will accurately measure the volume of cooled wort collected in the FV tank and its gravity in degrees Plato.  From the extract tables or extract equation determine the lbs of extract/bbl.  Multiply the lbs extract/bbl by the bbls of wort collected to get lbs of extract in the FV.  This is your realized lbs of extract from the grist.
 
Total up the lbs of potential extract from your grist and then divide into the lbs of extract collected in your fermenter and this will give you the brewhouse efficiency.  You can use this same ratio at each step in the brewhouse process to determine efficiencies and find sources of losses.  Brewhouse efficiencies of 90-93% for single infusion mash tuns are possible with a good mill, grind control and good lautering practices as well as minimal losses through to the FV tank.  Automated brewhouses with a lauter tun or mash filter will see brewhouse efficiencies of 96-98%.

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April 04
Bottle conditioning
by  Karl OckertNo presence information  on 4/4/2013 6:12 PM
Category: Packaging

Question

What is the best process and technique for introducing wort and yeast back into a beer just prior to packaging? The goal is to bottle condition the ale using wort that is produced in our brewhouse and yeast we pull from our FV cones.  I am concerned about hygiene and sterility of the transfer vessel, as well as of the final product.  Perhaps injecting pasteurized wort?  If we take the wort from our brew house post heat exchanger into a sterile vessel (keg), and then stored it in a cold box/refer, how long do you think that wort would be good for?

Answer

I worked with bottle conditioning for about 15 years (BridgePort IPA), and my first quesiton back to you is why do you want to use wort?  In my experience wort for bottle conditioning has problems with inconsistency, contamination and trub solids carryover.  Wort that is not used fresh but kept refrigerated is prone to contamination and flavor issues.  Use of dextrose sugar on the other hand will give you consistent, predictable control over fermentability, sterility and there is no trub or other solids that will carry through.  A good place to start experimenting with dextrose additions is about 1 lb per bbl.  To prepare the sugar solution and yeast inoculation:

  • Dissolve the sugar in a few gallons of water and heat to a minimum of 180 deg F for a minimum of 20 minutes
  • Pump the hot sugar solution into the bright beer tank
  • Pump beer into the tank
  • During the tank transfer, inject yeast slurry to achieve 1 million cells/ml at tank full
  • Check tank gravity and cell count to confirm
  • Mixing the sugar solution and yeast into the beer can be done by pump recirculation or agitator and should be done through the packaging of the beer
 
You might find that for bottling it’s a good idea to carbonate slightly to achieve fobbing prior to crowning.  Test your results by taking daily carbonation and gravity measurements over 14 days.

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April 03
Hydrometers
by  Karl OckertNo presence information  on 4/3/2013 5:02 PM
Category: Measurements

Question

I am a young brewer and have been wondering for some time about gravity of my lauter.  It is common knowledge that you stop collecting wort into the boil kettle when the gravity reads below 1.008 – 1.010.  However is this gravity being corrected for its elevated temperature or do you take it “as is”?  In other words, if I take a sample of wort toward the end of my lautering process and it reads 1.002 at 160 degrees Fahrenheit,  is this the point to stop?  Or do I correct for temperature which results in an actual gravity of 1.024.  To be safe I have stopped lautering when I fall below the specified range, but my efficiency takes a bit of a hit.  Just wondering if maybe I am being to careful.

Answer

It’s pretty well documented that you should stop lauter running’s at 2 deg Plato (SG 1.008) to avoid absorbing astringent tannins from the grain into the wort.  Your hydrometer is calibrated to read at a certain temperature which should be stamped or labeled on the stem, usually 60 deg F or 68 deg F, that is the temperature where the reading will be accurate.  The hydrometer measurement is based on the density of the wort, the warmer the liquid the less dense it is so it will read lower at a warm temperature than it will at a cooler temperature.  If you are reading the hydrometer at 160 deg F you are reading it at a very low density and it will give you an inaccurately low reading.  In your example you are taking a measurement at 160 deg F and getting a reading of SG 1.002 (0.5 deg Plato) with a  corrected reading of SG 1.024 (6 deg Plato), the latter is the accurate reading and you should continue to run off until you get a corrected reading of 2-2.5 deg Plato (SG 1.008-1.010).  The reason why you are losing efficiency in extracting from the mash is because you are cutting your run-off too early. 

To cool the sample quickly in the brewhouse you can use a small stainless cup for the sample sitting in a water bath with cold water running through or ice.  Stir the wort sample in the cup with a bi-metal or digital thermometer (never mercury!!) until the desire temperature is reached then take your hydrometer measurement.  Invest in a good quality calibrated hydrometer with temperature compensation to get the most accurate results, these are available through commercial brewing supply or laboratory supply websites.  The most accurate will come in concise ranges, ie 0-12 deg Plato and 9-21 deg Plato.

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April 03
Problems with foamy nitro beers
by  Karl OckertNo presence information  on 4/3/2013 4:10 PM
Category: Nitro beers

​Question

We are having problems with foaming in our nitro beer, we carbonate it to a low level and then use a blended gas to push it through the nitro tap. 

Answer

The thing that makes nitro beers give that wonderful “break out” of tiny bubbles and produce the creamy, stable head of foam is that unlike CO2, nitrogen does not dissolve well into beer but once dissolved it likes to stay there, in fact the nitro tap system forces the beer under high pressure through an “agitator plate” containing small holes in order to rouse the nitrogen to start its foaming process.  In the world of physics and gas laws substances try to come back into equilibrium with their atmospheric concentration and the atmosphere we are breathing right now is about 78% nitrogen, 21% oxygen and about 0.04% CO2.   That means that once nitrogen has been dissolved into the beer under high pressure it wants to stay in solution and forms those tiny bubbles which have a high surface tension and are wonderfully stable at the top of the pint.  Essentially a stable nitrogen beer is interrupted by large amounts of carbonation present, which unlike nitrogen, wants to come out of solution fairly readily (there being a much smaller concentration of CO2 in the atmosphere).  CO2 present in large amounts in the beer under the high driving pressure of a nitro tap will yield foam.  To produce nitrogenated beers you need to eliminate carbonation- CO2 is not your friend- that means:
  • Only Nitrogenate beer in a tank that is ASME rated for 2 bars (30 psig) or more and fitted with overpressure relief
  • Nitrogenate in the bright tank with pure Nitrogen gas (only- no CO2 blends) under high pressure, 25 psi plus and at cold temperature (0C)
  • Use pure Nitrogen gas in purging and pressurizing the keg, instead of CO2 or blends, at only a slightly lower pressure than the drive pressure from the bright tank
  • Use pure Nitrogen to counter pressure the bright tank while kegging

  • Nitrogen taps can use a “Guinness blend” of about 25% CO2 and 75% Nitrogen, this will allow a very small amount of carbonation to develop and assist the nitrogen breakout.

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Have you ever had a brewing, brewery, or technical question but didn't know who to ask?
 
Send your questions or comments or recipes to the MBAA Technical Director Karl Ockert.
 
Karl will post questions and answers as frequently as possible in a blog format as a benefit to all MBAA members.

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