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Lits fluidisés

Fluidised Beds

This microscope image shows the interior cell walls of a coffee bean. Image by Wenn, Royal Photographic Society. In our latest poll on the BH Facebook Group, you asked us to check this out: 'If flow goes in much faster than it comes out, then you have the potential to...

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Acier, verre, céramique?

Steel, Glass, Ceramic?

What's the most temperature-stable material to use when brewing? The short answer is: plastic cones are best. They absorb heat from the brew water less quickly, absorb less heat overall, and lose that heat to the air more slowly.  This conclusion may seem disturbing...

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Quelle est la meilleure conception de la tête de pulvérisation?

What’s the Best Sprayhead Design?

Photo: A UFO Sprayhead   Is it better to have as many holes as possible in your spray head; hardly any to make more agitation; or somewhere in between?   To achieve even extraction in batch brewing, it’s important to get all the grounds evenly wetted —...

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Recettes d'eau bricolage Redux

DIY Water Recipes Redux

A couple of years ago, we published a method for making your own water recipes, using concentrated mineral solutions, diluted with deionised water, to make a range of waters with different hardness and alkalinity. This post updates this, with new recipes that allow...

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Si ce n'est pas la canalisation, alors quoi?

If not Channelling, Then What?

"Professor Abbott told us he doesn’t really believe channelling occurs in espresso (except in drastic cases). So if not channelling, then what?" Only a few weeks ago we were telling you that over-extraction isn’t really a thing, and that it’s all caused by...

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Amende Migration

Fines Migration

You asked us to look into this topic, “In espresso, fines migration may not be as much of a thing as we thought.” Here’s what we found.  Fines are the smallest particles created when you grind coffee. Depending on who you’re talking to, they might be defined as any...

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Est-il préférable de filtrer les particules plus petites que 400μm?

Is it Better to Sieve out Particles Smaller than 400μm?

Or is it better just to leave them in, when brewing filter coffee? Back in 2012, our very own Matt Perger won the World Brewers Cup, using a 250μm sieve to remove fines. This created a more even extraction, which allowed him to extract higher without getting dry and...

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Match à mort de célébrité: Forchheimer vs Darcy

Celebrity Deathmatch: Forchheimer vs Darcy

A science professor told BH that with espresso, “in technical terms you have Forchheimer flows instead of good old Darcy flows”. What’s that? Keen readers of this series will remember Darcy’s law from our discussion of bed depth in espresso. Darcy’s law is an equation...

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Can You Please Summarise Cafe Imports’ Water Activity Paper   In our bi-weekly poll on the BH Facebook-group you asked us, "Can you please summarise this impressive research paper", which is based on a huge amount of cupping and data logging by influential green...

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Comment lire les équations chimiques

How to Read Chemical Equations

Any time you’re reading about chemistry, you’re going to come across chemical formulae and equations. You might well remember these from high school chemistry, but if it feels like a distant memory then this refresher might be useful. This post goes out to the BH...

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Qu'est-ce que la réaction de Maillard et pourquoi est-ce important?

What is the Maillard Reaction and Why is it Important?

The Maillard ‘reaction’ is actually a whole series of chemical reactions that are crucial to creating the characteristic flavours and brown colour of roasted coffee and many other foods - including chocolate, toast, and grilled steak. The reactions are named after...

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FAQ sur la science de l'eau

Water Science FAQ

      What is the difference (if any) between a mineral salt, a dissolved mineral, and a mineral ion? A salt, in chemistry, refers to any ionic compound (IUPAC, 1990). For example, table salt, sodium chloride, is an ionic compound composed of sodium...

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Parfois, les graines de Geisha ne ressemblent pas à la forme typique de Geisha

Sometimes Geisha seeds Don’t Look Like the Typical Geisha Shape

Geisha, or Gesha, is a highly prized variety, with a distinctive jasmine aroma, and bright fruity acidity. These distinctive characteristics mean it has dominated coffee competitions, and become infamously expensive as a result. Geisha beans are often quite large and...

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‘Seasoning’ group heads. Useful or nonsense?

‘Seasoning’ of a group head refers to the practice of making one or more ‘sink shots’ after cleaning an espresso machine - that is, shots that are thrown away with no attempt to taste them. Advocates of seasoning claim that the first shots have an unpleasant metallic...

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Le grand débat sur la distribution: les résultats

The Great Distribution Debate: Results

Tldr: we found a statistical difference between using the OCD and finger distribution, and between palm tapping and finger distribution — but no significant difference between palm tapping and OCD. But we’re going to continue researching and have some cool ideas for the next experiment.

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