WHICH IS BETTER?: Conical vs Flat Bottom Brewers

Introduction to Darcy's Law and Flat Bottom vs Cone Drippers

In this video, the speaker discusses the physics of percolation and introduces Darcy's Law. They also compare flat bottom and cone drippers for coffee brewing.

Understanding Percolation with Darcy's Law

• Darcy's Law is a fundamental concept in understanding the physics of percolation.

• It describes how fluid flows through a porous medium such as ground coffee in a cylindrical container.

• The law was first derived from observations.

Comparing Flat Bottom and Cone Drippers

• The speaker introduces the topic of comparing flat bottom and cone drippers for coffee brewing.

• A study conducted at the University of California at Davis compared the two types of filters using over 100 non-expert tasters.

• Over three weekends, participants tried nine to ten coffees overall, hitting 29 coffees in total with 118 different people tasting over 3,000 coffee samples served.

• Out of six variables tested (brew temperature, roast level, origin, acidity concentration, brew recipe, grind size), roast level was found to be the most significant factor affecting flavor perception.

Coffee Brewing Variables

In this section, the speaker discusses the different variables that affect coffee brewing and how they impact the taste of coffee.

Types of Coffee

• Different types of coffee have different tastes and strengths.

• People have different preferences when it comes to coffee strength and taste.

Importance of Brew Recipe

• The brew recipe is more important than the pour pattern, temperature, or other factors.

• The ratio of coffee to water is a crucial factor in determining the concentration and taste of coffee.

Basket Geometry and Grind Size

• The basket geometry (flat bottom vs semi-conical) affects the taste of coffee.

• People can distinguish between different basket geometries even with everything else being equal.

• Grind size also affects the taste of coffee but less so than basket geometry.

Taste Differences Between Flat Bottom and Semi-Conical Brewers

In this section, the speaker discusses how flat bottom brewers produce a different taste profile compared to semi-conical brewers.

Taste Profile for Flat Bottom Brewers

• Flat bottom brewers produce a floral, chocolatey, dried fruit flavor profile with black tea notes.

Taste Profile for Semi-Conical Brewers

• Semi-conical brewers produce a citrusy, berry-like flavor profile with sharp acidity notes.

Drippers and Peculiarities

In this section, the speaker discusses different drippers and their peculiarities.

Cone Drippers

• Cone drippers have a smaller hole at the bottom which can lead to clogging.

• The angle of the cone affects how water flows through it.

Flat Bottom Drippers

• Flat bottom drippers have a larger hole at the bottom which allows for faster flow rates.

• The shape of the flat bottom affects how water flows through it.

Wave Drippers

• Wave drippers have a wavy filter that slows down water flow and produces a unique taste profile.

Understanding Bypass in Coffee Brewing

In this section, the speaker explains how bypass occurs in coffee brewing and its impact on extraction.

The Impact of Ridges on Bypass

• The ridges inside a Hario V60 dripper push the filter off the side, creating gaps between the filter and wall.

• This allows water and coffee to bypass the bed of coffee, resulting in uneven extraction.

• Garnier's study showed that as more water is poured over the bed, bypass increases exponentially.

Cone vs. Flat Bottom Drippers

• In cone drippers like the V60, water tends to favor the middle as it flows through, resulting in a gradient from north to south.

• In flat bottom drippers, there is more even extraction on top with a gradient going down.

• Cone drippers have a concentration of coffee that gets less and less as you go down, making it easier for the middle to extract.

Evenness of Extraction

• Even if both cone and flat bottom drippers have evenness of extraction when quantified at each level (extra extracted, medium extracted, less extracted), they still have different extraction dynamics due to their shape.

Two Different Styles of Extraction

In this section, the speaker discusses two different styles of extraction that occur during pour-over coffee brewing.

Extraction with Water vs Extract

• The top layer of coffee is heavily extracted with water in pour-over brewing.

• As the water goes down, it extracts with extract, resulting in a different style of extraction.

• Even if both styles hit a similar extraction yield, they are still different.

Filter Dynamics: Kono and Flower Drippers

• The Kono dripper has ridges at the bottom and a smooth top part.

• If the paper filter is situated well, there will be complete suction against the smooth walls.

• Down at the bottom where the filter sticks off of the wall, there will be partial bypass.

• The flower dripper has finger-width grooves that push liquid straight down past the bed.

Wetting Your Filter and Mitigating Bypass

• Wetting your filter before use can help mitigate bypass by pushing it against those walls with water weight.

• Not wetting your filter can lead to inconsistencies from brew to brew due to folds happening as it gets wet.

• Pour-over brewers have uncontrollable bypass but there are ways to mitigate it.

Importance of Consistency in Coffee Grounds

• Using a blade grinder or cheap grinder and sifting out small particles will not produce similar grounds as a high-quality grinder due to differences in particle shape and flow rate through the bed.

• Uneven flow through the bed causes channeling which affects extraction consistency.

• Start coarser when dialing in pour overs or espresso and go finer until you find what you like for more even flow through the bed.

Brew Time and Temperature

In this section, the speaker discusses the variables of brew time and temperature.

Brew Time

• People were not able to tell the difference between a six-minute brew and a three-minute brew.

• The only issue with long brew times is if there is a lot of channeling going on.

• Grinding coarser is always better, especially when using a cheaper grinder.

Flat Bottom Brewers

• Frilly styles of filters like the Kalita filter or Stag filter have frills around the edges.

• These filters are easier to make and are used in labs often to filter things out.

• However, they promote a lot of bypass which can cause issues during brewing.

Other Styles of Filters

• A trend in recent years has been fitting other styles of filters into flat bottom brewers.

• Using tools like The Negotiator can help fit these filters against the walls well but still may result in minimal bypass.

• Different hole patterns on the bottom dictate flow rate coming out.

Increasing Water Weight

• Increasing water weight by increasing height can compact bed and increase flow rate.

• Pouring massive water columns may not be ideal for grounds with wide particle distribution as they can smush together more easily.

Bed Depth

• Wider brewers do not necessarily result in faster drawdown unless dose is increased systematically.

• Minimum bed depth should be maintained for proper extraction.

Flat Bottom vs Cone Brewer

In this section, the speaker discusses the differences between flat bottom and cone brewers. They conducted a test to compare the two and share their findings.

Differences in Extraction

• The extraction process is similar for both flat bottom and cone brewers.

• Different components are extracted differently in each of them.

• The biggest difference is how that extraction is occurring because of the shape of the bed.

Importance of Variables

• Roast level is the most important variable when brewing coffee.

• Recipe or ratio/concentration/TDS is second most important.

• Basket geometry (brewer itself), grind size, brew time, and brew temperature follow in order of importance.

Test Results

• The speaker conducted a test using identical recipes with both flat bottom and cone brewers.

• Both samples had identical TDS but tasted different due to different components being extracted differently.

• The speaker recommends conducting a similar test at home with same recipe, grind size, filter paper, etc. to compare results.

Conclusion

• Flat bottoms produce more balanced brew while cones produce more acidic and stratified brew.