TEMPERATURE, TIME AND TURBULENCE. AN ANALYSIS OF ITS EFFECT IN AN IMMERSION METHOD

Experiment Description:

Six different tests were carried out using an AeroPress. In all tests, 16 grams of coffee with a coarse grind 70 clicks and 230 grams of Lanjarón water at 95 degrees were used except in test 6, which was 85 degrees and without preheating the aeropress. Variables such as turbulence (N,S,E,W), temperature and total dissolved solids (TDS) were observed and recorded. The aeropress was preheated at the beginning of each test with steam from the kettle, reaching a constant temperature of 72 degrees. In tests 1, 2, 3 and 6 the Aeropress was extracted at minute 10, while in test 4 the extraction was carried out at minute 6 and in test 5 the extraction was carried out at 100 minutes.

Breakdown of Tests and Results

• Test 1 :
  • Turbulence at second 20 (27 cross) and at minute 8:30 (26 cross).
  • Temperature: Minute 3:30 (75 degrees) and Minute 9:50 (70 degrees).
  • TDS: 1.40%.
• Test 2 :
  • Maximum turbulence with multiple points recorded.
  • The temperature decreased noticeably during preparation.
  • TDS: 1.43%.
• Test 3 :
  • No turbulence.
  • The temperature decreased slightly but was noticeably the most stable compared to the other tests.
  • TDS: 1.38%.
• Test 4 :
  • No turbulence.
  • Extraction reduced to 6 minutes.
  • Temperature: Minute 2:50 (79 degrees), Minute 3:40 (78.5 degrees), Minute 5 (77 degrees).
  • TDS: 1.30%.
• Test 5 :
  • No turbulence.
  • The temperature gradually decreased, staying at about 38 degrees.
  • TDS: 1.56%.

Test 6 :

• No turbulence.
• Without preheating.
• The temperature gradually decreased, staying at about 65 degrees.
• TDS: 1.29%

Analysis:

The Saturation Point is a critical observation throughout these tests. Test 1 and 2, although showing variations in turbulence, had a similar TDS. This indicates that after a certain amount of agitation, adding more turbulence does not significantly improve extraction. Test 3, which completely eliminated turbulence, still achieved comparable TDS, reinforcing this point.

Temperature :

• Relevance and Observations : Maintaining the proper temperature is crucial for effective extraction. Test 3, with its relatively constant temperature, evidenced the importance of this factor, producing a TDS comparable to that of the tests with variable turbulence.
• Interaction with Turbulence : Test 2 demonstrated that high turbulence can cause a more rapid drop in temperature. This relationship suggests that although turbulence is beneficial to some extent, it can be counterproductive if it negatively affects thermal stability.
• Temperature emerges as the most critical variable. Tests indicate that even small variations in temperature can have a significant impact on extraction quality. Test 2, with maximum turbulence, showed the greatest temperature fluctuation, which could have affected its TDS. Test 3 and 4, with more stable temperatures, presented consistently lower TDS, but it should be noted that one test was 4 min shorter and both had an absence of turbulence, suggesting that temperature stability can lead to a more uniform and possibly more efficient extraction.

Turbulence :

• Relevance and Observations : Turbulence facilitates uniform saturation of the coffee and improves extraction. This statement is reinforced by comparing Tests 1 and 2 with Test 4, where the complete absence of turbulence reduced the TDS.
• Saturation Point : Despite the higher turbulence in Test 2, the TDS did not significantly exceed that of Test 1, indicating a saturation point in the extraction where additional turbulence is no longer beneficial.

Time :

• Relevance and Observations : Every second counts in coffee extraction. The differences in contact time in each test, especially between Tests 1 and 4, reflect their direct impact on TDS.
• The Extraction Time , varied in Test 4, also showed to be a relevant factor. Despite keeping the temperature and recipe consistent, reducing extraction time resulted in lower TDS. This highlights the importance of time in the relationship with the other variables.
• Despite the long duration of test 5 which took 1 hour and 40 minutes, there was not proportionally a very large difference with respect to the TDS, reaching 1.56%.

Detailed Comparison between Tests :

• Test 1 vs. Test 2:
• Despite the notable difference in turbulence, the TDS obtained were surprisingly similar. This suggests that, while turbulence is essential in the initial stages, its effect is attenuated as the process progresses.
• Test 2 vs. Test 3:
• These tests represent extremes in terms of turbulence. However, the consistency in temperature in Test 3 compensated for the lack of turbulence, resulting in similar TDS but not as much as Test 1 vs 2, with a difference of 0.05% between Test 2 vs 3 and a 0. .03 between 1 vs 2.
• Test 3 vs. Test 4:
• When comparing these tests, the impact of time becomes more evident. Despite eliminating turbulence in both tests, the drastic reduction in time in Test 4 led to a lower TDS, highlighting the relevance of time in the process.
• Test 4 vs. Test 5:
• These tests reveal the limit of the time-TDS relationship. Although Test 5 had an extremely long extraction time, the increase in TDS was not proportionally significant. This suggests that there is a temporary saturation point at which additional benefits from extraction become marginal.
• Test 1 vs. Test 5:
• Comparing these tests highlights the importance of time and its relationship with TDS. Test 5, with a much longer extraction time, only showed a slight increase in TDS compared to Test 1. This reinforces the idea that, after a certain point, extending the extraction time does not produce substantial improvements in the TDS.
• Test 3 vs. Test 6:
• These tests are relatively similar unlike the initial temperature which in test 3 was 95 degrees and in test 6 was 85 degrees apart from the fact that in test 6 the aeropress was not preheated, here the results were quite noticeable with a difference of 0.09%. This again reinforces the idea that temperature plays a crucial role.

Conclusion:

• Saturation Point and Turbulence: Turbulence, that is, the degree of agitation of the water and coffee, has an impact to a certain extent. Tests 1 and 2 are a clear testament to this, as despite the differences in turbulence, both resulted in similar TDS. This highlights the existence of a saturation point for turbulence, after which no significant additional benefit is obtained in extraction. Consequently, Test 3, which eliminated turbulence, still achieved comparable extraction, further underscoring this finding.
• Temperature - The Queen of Extraction: Throughout all the tests, temperature has proven to be the most influential and critical factor. Even small fluctuations can dramatically alter extraction quality, evidenced by TDS differences in tests where temperature varied. A stable temperature, or its controlled manipulation, is essential for optimal extraction. For example, in Test 2, despite maximum turbulence, the greater temperature fluctuation may have negatively affected its TDS. It is also observed that the crust that forms acts as a seal in a certain way and prevents further temperature loss.
• The Delicate Art of Time: Extraction time not only determines the duration of contact between water and coffee, but also intervenes in the interaction with turbulence and temperature. Although Test 4 held other variables constant, the reduction over time resulted in a lower TDS, underscoring its importance in the overall extraction process.
• On the other hand, we can observe with test 5 that despite the enormous difference in contact time with respect to the previous tests, the TDS has not changed proportionally in a drastic way. This once again reinforces the idea of ​​the saturation point of water.
• Temperature, especially after looking at the results of Test 6, emerges as the most critical factor in extraction using AeroPress.

• Each variable, whether time, turbulence or temperature, plays a critical role and is intrinsically interconnected with the others. Achieving perfection with AeroPress and any other immersion method is both a challenge and an opportunity, allowing baristas to explore and experiment to find that flawless extraction. The search for the perfect cup, then, lies in the precise balance of these variables and a deep understanding of their interaction.