Exploring water temperature consistency.
In part 3 of my Oracle Touch consistency exploration, I will focus on the group head of the Oracle Touch, specifically temperature consistency. This article relies on data from the Consistency Part 3 video, linked at the bottom of this page.
For our experiment setup, I am using the Scace Thermofilter, loaded into the Breville Oracle Touch naked portafilter. I have a digital thermometer and a computer to log the temperatures in real-time as I conduct each extraction.
I will be testing the actual brewing temperatures when the water temperature is set on the machine menu to 190 Degrees Farenheit, 195 degrees, 200 degrees, and 205 degrees.
For each extraction, I will highlight the temperature at the 5 second mark, which is when the puck is fully soaked from pre-infusion, at the10 second mark, which is around the time of your first espresso drop, and at 28 seconds, which is around the end of a shot for a medium roast.
Here is the data I collected for each test:
When the machine was set at a 190 degrees, the water temperature
- at 5 seconds was 151.6
- at 10 seconds it was 188.9
- and at 28 seconds it was 199.1
When the machine was set at 195 degrees, the water temperature
- at 5 seconds was 179.3 - at 10 seconds it was 194.6 - and at 28 seconds it was 200.9
When the machine was set at 200 degrees, the water temperature - at 5 seconds was 182.3 - at 10 seconds it was 199.2 - and at 28 seconds it was 207 degrees
When the machine was set at 205 degrees, the water temperature - at 5 seconds was 189.6 degrees - at 10 seconds it was 204.2 - and at 28 seconds it was 211.9
You can see that the temperature variation from the machine setting to actual brewing temperature at the first drop of espresso is fairly small: - just 0.4 when set at 195
- 0.8 when set at 200
- and 0.8 when set at 205
So the machine actually does a pretty good job at getting the brewing temperature close to the target by the start of the extraction.
From 10 seconds to 28 seconds, the water temperature rises gradually in all four tests and ends with a more significant variation from the machine setting:
- 5.9 degrees when set at 195 degrees
- 7 degrees when set at 200
- And 6.9 when set at 205
From my testing, I can say that the machine does not maintain brewing temperature perfectly even. So in terms of consistency, perhaps the water temperature fluctuation could impact your extraction. So if temperature is important for you, take into account this data.
Personally, and this is just my opinion, I don't think that a gradual increase of 6 to 7 degrees is enough to ruin an extraction, unless perhaps if you are already brewing at 205... because a peak temperature of 211.9 is really quite high. Obviously, a 6 degree variation is not ideal, but I am generally happy with my extractions, so I am not going to stress about this; my shots never taste bad or burnt when I have a good extraction.
Nevertheless, given this data, I plan to experiment with some new temperatures: I will start using 194 for dark roast (instead of 195), 199 for medium roast (instead of 200), and 202 for light roast (instead of 205). I think this adjustment will mitigate the downside of the temperature increase for each type of roast.