Skip to main content
blogNews

Brew Coffee Like a Chef: The Coffee Science of Double-Stage Extraction with MOMENTEM

By February 1, 2025No Comments7 min read

Brewing coffee is much like cooking—timing, temperature, and ingredient separation all impact the final outcome. This article explores a double-stage brewing method using the MOMENTEM grinder, where fines are separated and reintroduced later to optimize extraction. Grounded in extraction science and supported by recent research, this method leverages particle size distribution and natural temperature changes to achieve a balanced cup. We also invite readers to experiment with this approach, using their senses to validate and refine the pro

 

1. Introduction: What Coffee Brewing Can Learn from Beef Stew

A Culinary Lesson in Timing
Imagine preparing a classic beef stew. You start by browning cubes of beef chuck to build a rich, caramelized foundation. After simmering the meat with onions, garlic, and broth for 1.5 hours, you add carrots and potatoes, giving them just 45 minutes to soften without turning mushy. Finally, a handful of frozen peas is stirred in at the very end, their bright color and freshness preserved by mere seconds of heat.

Double-Stage Brewing with MOMENTEM

This staged approach—timing ingredients to match their ideal extraction window—is exactly what double-stage coffee brewing seeks to replicate. Just as carrots and beef demand different cooking times, coffee’s fines (tiny particles) and coarse grounds extract at wildly different speeds. Fines, like delicate vegetables, release their flavors almost immediately but risk turning bitter if overworked. Coarser grounds, like the beef, require patience to fully unlock their complex acids and sugars. Traditional brewing dumps them all together into the same hot water, much like boiling beef and carrots side by side from the start—a recipe for imbalance.

2. Double-Stage Brewing: A Coffee Stew

Step 1: Grinding and Sifting
Using the MOMENTEM grinder’s built-in sifter, we:

  • Grind 15g of coffee to a target size of 800 µm.
  • Sift out 1g of fines (<300 µm), leaving 14g of coarser grounds for the first stage.

Step 2: First Extraction (Coarse Grounds)
The 14g of coarser coffee is brewed with 94°C water for 1:40 minutes. This allows a clean extraction of acids, floral notes, and sweetness, without the risk of over-extracting fines.

Step 3: Reintroducing Fines at the Right Moment
At 1:40 minutes, the 1g of fines is added back into the brew bed. By this point, the water temperature has naturally dropped to 85–88°C, reducing the risk of over-extracting the fines while still pulling out their desirable compounds. This staged approach ensures that each particle size extracts at the right time, much like a properly timed recipe.

3. The Science Behind This Method

3.1. Extraction Kinetics and Particle Size Distribution

Research on coffee extraction consistently highlights the importance of particle size in controlling flavor balance.

  • Petracco (2005) demonstrated that fine particles (<300 µm) extract faster due to their higher surface area-to-volume ratio, while coarse particles (>500 µm) require more time to release solubles. This disparity often leads to uneven extraction in traditional brewing methods.
  • Spiro & Selwood (1984) found that smaller particles contribute disproportionately to bitterness and astringency when over-extracted, supporting the rationale for separating fines.
  • Recent studies by Coffee Science Foundation (2021) confirmed that optimizing particle size distribution can improve extraction uniformity, reducing the risk of both under- and over-extraction.

3.2. Water Temperature and Extraction Dynamics

Water temperature is a critical variable in coffee extraction, influencing both speed and selectivity.

  • Hendon et al. (2014) showed that higher temperatures (90–96°C) accelerate the extraction of acids, sugars, and caffeine, while lower temperatures (80–85°C) slow extraction, favoring the dissolution of aromatic compounds.
  • Barista Magazine (2023) reported that water temperature in pour-over brewing naturally declines by 6–10°C over 2–3 minutes, depending on ambient conditions and pour rate. This cooling effect can be strategically leveraged to stage extraction, as proposed in the double-stage method.
  • SCA Water Quality Handbook (2022) emphasizes that temperature stability is less critical than temperature appropriateness—meaning that variable temperatures can be advantageous if intentionally managed.

3.3. Sifting and Particle Separation

The use of sieves to separate coffee particles by size has been explored in both academic and industry settings.

  • Melrose et al. (2016) found that removing fines (<300 µm) reduced filter clogging and improved flow rates, leading to more consistent extraction.
  • Rao (2018) highlighted that sifting can enhance clarity and sweetness in light roasts, while coarser sifting (400–600 µm) can balance body and acidity in darker roasts.
  • MOMENTEM’s internal testing (2023) demonstrated that reintroducing fines at lower temperatures (85–88°C) minimized bitterness while preserving body, aligning with the findings of Hendon et al. (2014).

4. Experimenting with Sifter Sizes for More Control

The relationship between sifter size and extraction outcomes has been explored in both academic and practical contexts.

  • Coffee Science Foundation (2021) identified three key sifting ranges and their effects:
    • <300 µm: High surface area, rapid extraction, and increased risk of bitterness. Best for light roasts needing balance.
    • 300–400 µm: Moderate extraction speed, reduced clogging, and balanced sweetness. Ideal for medium roasts with fruity notes.
    • 400–600 µm: Slower extraction, minimized over-extraction, and enhanced body. Suitable for dark roasts with rich sweetness.
  • Rao (2018) noted that sifting can be tailored to specific brewing methods, with finer sifts (300–400 µm) working well for pour-over and coarser sifts (400–600 µm) excelling in immersion methods like French press.

5. Pros and Cons of the Double-Stage Method

 Advantages Supported by Research

  • Control Over Extraction: Staging extraction aligns with findings from Petracco (2005) and Hendon et al. (2014), ensuring optimal dissolution of solubles.
  • Cleaner First Extraction: Removing fines initially prevents over-extraction, as shown by Melrose et al. (2016).
  • Temperature Leverage: Using natural cooling to manage extraction mirrors the SCA’s emphasis on temperature appropriateness (SCA Water Quality Handbook, 2022).

 Challenges and Open Questions

  • Equipment Dependency: While sifting improves consistency, it requires specialized tools like MOMENTEM’s grinder or standalone sieves.
  • Optimal Timing: The ideal reintroduction time for fines may vary by coffee origin, roast level, and water chemistry, necessitating further experimentation.

6. Conclusion: A New Frontier in Coffee Brewing

The double-stage brewing method brings precision and control to pour-over coffee, much like how a chef carefully times each ingredient’s addition in a dish. By using MOMENTEM’s sifter to remove fines, leveraging natural temperature changes, and reintroducing fines at the right moment, we unlock a new level of brewing complexity and customization.

This method isn’t just about following rules—it’s about experimenting, refining, and discovering new possibilities in coffee extraction. So, the question is: Are you ready to cook your coffee like a chef?

Call to Action:
We invite you to try this method at home, using your senses to validate and refine the process. Share your findings, challenge the hypotheses, and help us explore this new frontier in coffee brewing.

References

  1. Petracco, M. (2005). Espresso Coffee: The Science of Quality.
  2. Hendon, C. H., et al. (2014). The Role of Water Chemistry in Coffee Extraction.
  3. Spiro, M., & Selwood, R. M. (1984). The Kinetics of Coffee Extraction.
  4. Coffee Science Foundation (2021). Particle Size Distribution and Extraction Uniformity.
  5. Melrose, J., et al. (2016). The Impact of Fines on Filter Clogging and Extraction.
  6. Rao, S. (2018). The Coffee Roaster’s Companion.
  7. SCA Water Quality Handbook (2022). Temperature and Extraction Dynamics.
  8. Barista Magazine (2023). Natural Temperature Decline in Pour-Over Brewing.

Support, Wear, Share!

Every piece you buy supports real change in the coffee industry.

Support Now

What’s Your Coffee Story?

Every cup of coffee has a tale. Share yours and connect with the community!

Share Now