It has been a month since we last brewed, and we need to have the new beer ready before the previous batch runs out. Today we have two objectives.
- The inaugural brew on our new set-up and test the ice bath as an effective chilled water source for cooling wort.
- Test the effect on beer flavor of mashing in at ‘protein-rest’ temperature (~45 degrees Celsius) vs mashing in at conversion temperature (~65 degrees Celsius).
Objective one was completed rather successfully. The system needs further optimization, but overall, the brew day went very smoothly. We discovered we could not fit the brew stand through the gate to the back yard. So we brewed in the driveway. We met more neighbors in a few hours of brewing than we had in an entire month. We were able to cool 4 gallons of wort to 20 degrees Celsius with 5 gallons of water with 10 pounds of ice. The water out from the heat exchanger was added back to the ice bath. By the time the wort was cooled, the ice had melted, but no significant increase to the water temperature was observed. Got to love the isothermal nature of a phase change.
Objective two is to determine if a low temperature ‘protein-rest’ will affect the beer flavor/aroma/mouth feel. We are more concerned with residual B-glucanase activity. Depending on one’s school of thought, this enzyme might have been inactivated in the malting process during kilning, but there is anecdotal evidence that a low temperature rest may result in the break down of B-glucans. With any luck, the result of both experiments will be a drinkable beer. Recipe is listed below, with identical recipes used for each experiment.
Grain Bill: 12 lbs Domestic 2-Row, 1 lb American Pale, 1 lb Crystal 75 L
Hops (Pellets): 0.5 oz Magnum (12.1% AA) 60′, 1 oz Willamette (5.1% AA) 15′
Boil Kettle Volume: 7.5 gallons
Cellar Volume: 4 gallons
Yeast: White Labs PurePitch WLP002 British Ale
Experiment 1 Gravity: 1.0611
Experiment 1 Efficiency: 59%
Experiment 2 Gravity: TBD
Experiment 2 Efficiency: 59.5%
Experiment 1: Mash-in at 48 degrees Celsius and rest for 20 minutes. 2:1 water to grist ratio (w:w). Using the plate heat exchanger, recirculate wort to increase temperature to 64 degrees Celsius and allow conversion to proceed for 30 minutes. Sparge at 72 degrees Celsius. Boil for one hour, whirlpool. Fermentation temperature 20 degrees Celsius.
Experiment 2: Mash-in at 64 degrees Celsius and allow conversion to proceed for 30 minutes. 2:1 water to grist ratio (w:w). Sparge at 72 degrees Celsius. Boil for one hour, whirlpool. Fermentation temperature 20 degrees Celsius.
- Experiment 1 mash-in temperature was a higher than desired, and conversion temperature was lower than target (67 degrees Celsius). To ensure that the only variable was the ‘protein-rest’, experiment 2 conversion temperatures were also modified.
- Experiment 2 the fly sparge became a batch sparge due to an airlock in the pump, thus adding another variable to our experiment.
- At the end of our sparge, the wort was tested. The reading was ~7 degrees Plato. There is still sugar to be recovered. We could slow down our sparge rate to increase efficiency of sugar recovery. This will also increase the recovery of undesirable compounds (tannins, polyphenols).
- We experienced a greater boil off than anticipated based on our experiences from a month ago. It should be noted that we had a much stronger boil an greater evaporation because we were not fighting the wind to keep a constant flame as we had to do our previous brew day.
- We used approximately 40 gallons of water to generate 8 gallons of beer.
- Fermentation started Monday morning.