Basic Brewing Radio Interview:
I bought a microscope and hemocytometer and had a microbiology buddy of mine come by and show me how to use them (Thanks Adam!). So, what to do with this new found knowledge? A pitching rate experiment of course! I’ve read over and over again that underpitching will boost esters/phenols and overpitching has the opposite effect. Take that and combine it with my wife’s love of Hefeweizens and testing this theory with German Wheat Spicy Bananafantasticness is a no brainer.
The basic test is this. Brew 3+ gallons of 1.050 Wheat DME based wort, split that across 3 different 1 gallon fermenters and pitch those from the same yeast starter but with different amounts of starter to vary the pitch rate. So, same beer, same yeast just varying amounts of yeast. Here is the recipe with notes:
Beer Name: hefeweizen test ebiab 1
Original Gravity: 1.050
Final Gravity: 1.013
Alcohol: 4.9 %
Bitterness: 10 IBUs
Kettle Gravity (start of boil): 1.042
Starting Boil Volume: 4.125
Boil Duration: 30 Minutes
Evaporation Rate: 1.25 Gallons per Hour
Final Boil Volume: 3.5
|Weight (Lbs)||% by Weight||Name||Yield||SRM|
|4.15||100.0||Briess DME Bavarian Wheat||91.3||8.0|
|Weight (ozs)||Name||AAU||Time (mins)||Use||IBUs / Addition|
Yeast and Friends
|1 vial||White Labs WLP300 Hefeweizen Ale|
|.5 tsp||Yeast Nutrient (Wyeast)||10|
starter made on 4/28/15 so viability should be high (assuming ~80%)
this starter should generate 290 billion cells in 1.5L
I am doing 3 x 1 gallon test beers all from the same wort (1.050 wheat dme with 10 IBUs of spalt)
cooled to ~63F and fermented at 65F
beer 1 pitch rate of .375 (half of standard ale rate) which is 17.5 billion cells in 1 gallon which for above starter would be 90 mL
beer 2 pitch rate of .75 (standard ale rate) which is 35 billion cells in 1 gallon which for the above starter would be 180 mL
beer 3 pitch rate of 1.5 (double the standard ale rate) which is 70 billion cells in 1 gallon which for the above starter would be 360 mL
will take remainder and test cell count to see how close i was
Temperature at Bottling: 72 F
Volumes of CO2: 3
Amount of Beer: 1 Gallons
Amount of tableSugar to add: 33.1 grams or 1.2 ounces
4/28/15 Made 1.5L starter w/ 150grams of light pilsner dme and 1 vial of WLP300
4/29/15 starter had significant blow off so likely lost a good amount of yeast
pretty standard extract brewday. no issues.
beer 1> no kreusen
2> a little kreusen
3> full blown kreusen and chugging along
5/3/15 all still have big kreusens but bubbling is beginning to slow.
5/4/15 fermentation appears to be done and yeast is beginning to drop
did cell count of leftover starter.
53,43,41,49,48 = 46.8 avg
46.8 x 25 (total cells in field)
x 10 (I did a 10:1 dilution)
x 10,000 (hemocytometers field size)
= 117 million cells / ml
in 1.5L starter this is 175.5 billion cells which is 60% of what I expected. this is easily explained by significant blow off starter.
so, actually pitch rates are:
1> 10.5 billion cells (30% of 0.75 million cells/ml/degree Plato)
2> 21 billion cells (60%)
3> 42 billion cells (120%)
5/14/15 bottled. each was just under a gallon in the bottling bucket so to get 3.0 volumes I did 32 grams of sugar in 1/2 cup of filtered water which I brought to a boil, cooled and added to the bottling bucket and stirred in very thoroughly. produced 6 bottles of each beer.
6/2/15 took beers to homebrew club meeting and had 13 tasters. pretty good agreement that 30% pitch rate had the most banana character and the overpitch 120% was more muted and 60% was in between with more balance of banana and clove. almost no agreement on which was preferred. i tested earlier with my wife and we both preferred the 60%. no real flaws detected so all turned out well.