Beer Style: American Pale Ale
4.5 gallon batch
4.2% ABV
42IBU
Grainbill:
5.25lb Briess Pale Ale - Liquid Malt Extract
Boil:
1oz Brewers Gold @ 30 minutes
1oz Brewers Gold @ 15 minutes
Yeast: Safale - US05
2g for 1.3 gallons (Low)
4g for 1.3 gallons (Recommended)
8g for 1.3 gallons (High)
Gravity:
OG: 1.042 / FG: 1.01 (all conditions)
Observations:
12 hours after pitching.
Overpitched carboy was already quite active. Beer was cloudy with yeast cells and beginning to churn.
Recommended rate carboy was beginning to form a small krausen and appeared slightly more active than the underpitch carboy.
24 hours after pitching: The "Blups Per Minute" Calculation (BPMs)
24 hours after pitching, a "Blups Per Minute" calculation was taken in order to determine any differences in CO2 production as a proxy for fermentation activity.
1 Blup is defined as one bob of the airlock.
All airlocks were filled to the same level at the time blups were counted.
A Casio Watch was used to time 1 minute. 3 1-minute Blup readings were taken for each of the 3 carboys to determine an average Blups per Minute.
Underpitch: Average was 14 BPMs
Recommended: Average was 19 BPMs
Overpitch: Average was 27 BPMs
As you can see, the BPM rates for each of the experiment conditions is consistent with the assumption that additional yeast would result in more rapid fermentation activity 24 hours after pitching. Unfortunately, scientists were away from the laboratory as fermentation slowed and data is not available on when each carboy finished fermentation.