Garrett_McT
Seeker of Knowledge, and Homebrew
HBT Community,
I have experienced a weird anomaly while monitoring the temperature of my lager fermentation. White Labs German Lager Yeast WLP830. I have been monitoring the wort/fermenting beer temperature periodically, while also continuously monitoring the ambient fridge temperature through the use of a Govee thermometer. After my diacetyl rest I reached a gravity of 1.016, whereas my final target gravity is 1.015. I assumed that I reached my final gravity and pushed it into my slow decline for the cold crash. I took a couple gravity readings while I have been monitoring the cold crash temperature and both came back at 1.019. I was wondering if this was possibly an anomaly due to some aspect that I am over looking. For instance while I am taking gravity readings of my finished boiled wort, I notice if I do not stir the wort vigorously then I get gravity readings below the actual true reading. I am hoping that this is a similar case because I hope that there is not some residual fermentable sugars lying around in my almost completed beer leading to bottle bombs later.
For your information the following data was collected. I have far more data if it is needed.
Target Primary Wort Temp = 52.0 F
T = 0 min, Wort Temp = 53.0F, Ambient Fridge = 39.92F, SG = 1.065
T = 96 hr 30 min, Wort Temp = 51.8 F, Ambient Fridge = 47.84 F, SG = 1.046
T = 145 hr 15 min, Wort Temp = 52.4 F, Ambient Fridge = 48.2 F, SG = 1.022
T = 159 hr 45 min, NOTE: Start of Diacetyl Rest, Target Diacetyl Rest Temp = 60 F
T = 159 hr 45 min, Wort Temp = 52.5 F, Ambient Fridge = 48.38 F, SG = 1.020
T = 213 hr 15 min, Wort Temp = 74.4 F, Ambient Fridge = 75.2 F, SG = 1.016
T = 237 hr 0 min, NOTE: Start of Cold Cash, Target Daily Decline = 3.7 F
T = 268 hr 15 min, Wort Temp = 50.9 F, Ambient Fridge = 48.02 F, SG = 1.019
T = 329 hr 30 min, Wort Temp = 49.6 F, Ambient Fridge = 45.5 F, SG = 1.019
I have approximately 2 days left in my cold crash to reach 38 degrees. Then I plan on bottle conditioning at Primary Fermentation temperature for just short of 4 weeks, and cold storing for 4 weeks. I used a refractometer for all of my gravity readings, and the refractometer has given me consistently true results as compared to my hydrometer.
I feel as though since the wort temperature had dropped at T = 213 hr 15 min to below the ambient fridge temperature that this was a true sign that fermentation has ended, due to the fact that yeast fermentation is considered an exothermic reaction. Especially because, although lager yeast is not top fermenting, there was a sufficient amount of yeast which fell from the top layer at this same time.
But what I could have easily have overlooked is the fact that the temperature change as the fridge warmed during the diacetyl rest changed quicker than the fermenting wort temperature resulting in the Wort Temp<Ambient Fridge, along with the fact that since the diacetyl temp went way higher than I had wanted, so much that it was outside the range of the specified temperature for the yeast culture, which caused the yeast to go dormant and the result of the yeast at the top falling to the bottom.
Thoughts, expertise, experience and opinions are all welcomed! Thank you for your time and sharing of your enlightened knowledge,
Garret_McT
I have experienced a weird anomaly while monitoring the temperature of my lager fermentation. White Labs German Lager Yeast WLP830. I have been monitoring the wort/fermenting beer temperature periodically, while also continuously monitoring the ambient fridge temperature through the use of a Govee thermometer. After my diacetyl rest I reached a gravity of 1.016, whereas my final target gravity is 1.015. I assumed that I reached my final gravity and pushed it into my slow decline for the cold crash. I took a couple gravity readings while I have been monitoring the cold crash temperature and both came back at 1.019. I was wondering if this was possibly an anomaly due to some aspect that I am over looking. For instance while I am taking gravity readings of my finished boiled wort, I notice if I do not stir the wort vigorously then I get gravity readings below the actual true reading. I am hoping that this is a similar case because I hope that there is not some residual fermentable sugars lying around in my almost completed beer leading to bottle bombs later.
For your information the following data was collected. I have far more data if it is needed.
Target Primary Wort Temp = 52.0 F
T = 0 min, Wort Temp = 53.0F, Ambient Fridge = 39.92F, SG = 1.065
T = 96 hr 30 min, Wort Temp = 51.8 F, Ambient Fridge = 47.84 F, SG = 1.046
T = 145 hr 15 min, Wort Temp = 52.4 F, Ambient Fridge = 48.2 F, SG = 1.022
T = 159 hr 45 min, NOTE: Start of Diacetyl Rest, Target Diacetyl Rest Temp = 60 F
T = 159 hr 45 min, Wort Temp = 52.5 F, Ambient Fridge = 48.38 F, SG = 1.020
T = 213 hr 15 min, Wort Temp = 74.4 F, Ambient Fridge = 75.2 F, SG = 1.016
T = 237 hr 0 min, NOTE: Start of Cold Cash, Target Daily Decline = 3.7 F
T = 268 hr 15 min, Wort Temp = 50.9 F, Ambient Fridge = 48.02 F, SG = 1.019
T = 329 hr 30 min, Wort Temp = 49.6 F, Ambient Fridge = 45.5 F, SG = 1.019
I have approximately 2 days left in my cold crash to reach 38 degrees. Then I plan on bottle conditioning at Primary Fermentation temperature for just short of 4 weeks, and cold storing for 4 weeks. I used a refractometer for all of my gravity readings, and the refractometer has given me consistently true results as compared to my hydrometer.
I feel as though since the wort temperature had dropped at T = 213 hr 15 min to below the ambient fridge temperature that this was a true sign that fermentation has ended, due to the fact that yeast fermentation is considered an exothermic reaction. Especially because, although lager yeast is not top fermenting, there was a sufficient amount of yeast which fell from the top layer at this same time.
But what I could have easily have overlooked is the fact that the temperature change as the fridge warmed during the diacetyl rest changed quicker than the fermenting wort temperature resulting in the Wort Temp<Ambient Fridge, along with the fact that since the diacetyl temp went way higher than I had wanted, so much that it was outside the range of the specified temperature for the yeast culture, which caused the yeast to go dormant and the result of the yeast at the top falling to the bottom.
Thoughts, expertise, experience and opinions are all welcomed! Thank you for your time and sharing of your enlightened knowledge,
Garret_McT