Aeropress Comparisons Part 3: Temperature Tests and Results

Equipment:

• Flow-control caps. Aeropress steel flow-control cap for the glass and steel versions, and the Fellow Prismo cap for the plastic brewer
• Plastic Aeropress - smoked version purchased during Alan Adler's AeroPress leadership
• Glass Aeropress Premium
• Aeropress Steel
• Preheat water - Mueller electric kettle that heats to boiling
• Brew water - Fellow electric kettle that heats to 200F/93C
• Timemore Millab E01 grinder set to 4.0
• 1 stainless steel carafe for brewing into
• 2 Fellow Carter mugs (12 ounce)
• ThermoWorks Thermapen ONE thermometer

Temperature Tests

Recipe - The Tim Wendelboe from the Aeropress Timer app: 

• Traditional (non-inverted) brewing
• 15g of coffee ground to medium-fine
• Water at 200F (93C). The recipe calls for 195g of water, but I used 240g
• Pour all 240g of water, stir for 5 seconds, steep for 30, stir for 10, and plunge for 30
• Beans: Joe Bean Jeovany Lara Honduras 

Temperature control: 

This test is intended to determine whether or not preheating the individual brewers made a difference in the cup.  One brewer will be tested each day by brewing two sequential 1-serving recipes. The first brew will be done with no preheating, and the second with preheating. I took temperature readings at the following times:

• As soon as the Aeropress was filled with brew water (to see how much the brewer itself drops the temperature)
• Just before plunging (to see how well the brewer maintained temperature during the brew process)
• The temperature in the steel carafe as soon as pressing was complete (before diluting with an additional 100 grams of brew water)
  

Process:

1. Grind beans
2. Heat brew water and assemble brewer
3. Place grounds in brewer
4. Brew according to the recipe above, taking temperature readings
5. Add 100g of additional brew water
6. Transfer brew to Carter insulated flask and close the flask
7. Heat preheat water, then rinse and reassemble the brewer
8. Grind beans
9. Fill brewer with preheat water; wait 10 seconds
10. Pour preheat water from brewer into steel carafe; wait 10 seconds and discard water
11. Place grounds in brewer
12. Brew according to the recipe above, taking temperature readings.
13. Add 100g of additional brew water
14. Transfer brew to Carter insulated flask, close the flask.
15. Wait 4 minutes, and remove the lid of the preheated brew and allow to cool for 2 minutes before performing taste test.

Taste Results:

• Steel - While both were very good, the coffee made in the preheated brewer was noticeably better.
• Plastic - Both were very good. Preheated was slightly better, less astringent.
• Glass - Both were excellent. I'm not sure why this one turned out so much better than the other two in this instance (practice? I've been performing this test all week). Normally, the glass doesn't produce remarkably better cups.  The room-temp brewer produced a smoother flavor, and the preheated brewer produced a more intense flavor.

Temperature Readings

Fahrenheit / Centigrade	AeroPress Classic Plastic	AeroPress Glass	AeroPress Steel
Ambient Room Temperature	65 / 18.3	65 / 18.3	60 / 15.6
Room-Temp Brewers
Brew temp just after filling with water:	183 / 83.9	179 / 81.7	186 / 85.6
Brew temp just before pressing:	173 / 78.3	169 / 76.1	178 / 81.1
Temperature of coffee just after pressing	156 / 68.9	151 / 66.1	159 / 70.6
Preheated Brewers**
Brew temp just after filling with water:	188 / 86.7	189 / 87.2	189 / 87.2
Brew temp just before pressing:	179 / 81.7	180 / 82.2	182 / 83.3
Temperature of coffee just after pressing	162 / 72.2	164 / 73.3	165 / 73.9

Articles in the series:

Aeropress Comparisons Part 1 - First Impressions: Aeropress Steel

Aeropress Comparisons Part 2 - Single and Double Serving Tests and Results

Aeropress Comparisons Part 3: Temperature Tests and Results (this article)