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#161: Post by decent_espresso (original poster) »

Scott Rao interviews John Buckman

A one hour conversation recorded live from Instagram. We'll be releasing chopped-up single-question videos from this, next week. From https://www.instagram.com/p/CHy4aw8pRoC/

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#162: Post by decent_espresso (original poster) »

12 questions from when Rao interviewed Buckman

Scott Rao interviewed me last week, and we've split the hourlong conversation into 12 questions, which makes short, sweet & "to the point" viewing.
http://www.youtube.com/playlist?list=PL ... GKuPr1jNRH

Calling it an interview isn't quite right as Scott (quite rightly) spoke a fair amount. I tend to babble on too long in most interviews, but with Scott I found that I reigned that tendency in, likely because I knew that he'd continue to pilot the conversation is an interesting direction.

Scott suggested to me, that we have another conversation in maybe 6 months. However, as this one went so well, I'm thinking of perhaps more regularly conversations between the two of us. And perhaps with less of of an interview structure, more of a conversation about topics besides Decent, might be quite interesting.

-john


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shotwell

#163: Post by shotwell »

There are some real gems in this interview John. A particularly great insight is the thought process behind the fill stage in blooming shots; I used to think about using a pressure mark or slight beading with the Bianca to do this. Using time to fill a reasonably consistent volume made this much easier. Thanks for taking the time to break all that down.

icantroast

#164: Post by icantroast »

Yeah, I have to say, I'm not really in the market for a Decent but the guy who made it seems like a really top notch dude. Love his transparency and how well he explains everything.

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#165: Post by decent_espresso (original poster) »

A unified theory of espresso making recipes

I've been working on a "unified theory of espresso making recipes", which results in 4 "mother" recipes.


The optimal espresso curve

But before I plunge into that, I want to make the argument that there is an arguably optimal pressure curve for espresso recipes.

You can see it as the pressure profile that occurs naturally when constant flow water is used to make an Allongé recipe coffee on the Decent. The resulting pressure is a reflection of the declining puck resistance over time, as the puck loses material to the espresso drink.





This curve has the following characteristics:
  • a preinfusion that takes about 10 seconds before pressure builds
  • a peak pressure around 8.6 bar
  • an end pressure around around 4 bar
  • a total espresso making time around 30 seconds
I think it's no coincidence that this is exactly the pressure curve that most spring lever espresso machines naturally give you. The people who designed their machines, very likely did this on purpose, by using their eyes and taste buds, as they didn't have access to the data we now have.

I'm going to argue that the "best" espresso recipes are all variations on the curve above, as they recognize the reality of the physics of the coffee puck during espresso extraction.

For me, "best" = "tastes most pleasing" = "most good flavors, minimizing bad flavors". I realize that people have different levels of acidity they seek, and I'm deliberately putting that aside here, focussing instead on flavors.



The "four mother" recipes

My position is: a bean's roast level is the most important consideration in choosing a recipe for making espresso.

This is because, the darker a coffee bean is roasted:
  • the more soluble it becomes ("more easily gives up material to water")
  • the more integrity the coffee puck will have (it is less likely to fall apart and channel badly during espresso making).
Put another way: the less soluble a bean is, the more your recipe will have to work harder to get material out of the bean.

The three main ways to get more material out of a bean are:
  • increase time: the amount of time that the beans are in contact with water
  • increase water flow rate through the grounds bean puck
  • increase the water temperature, which increases the efficacy of the water to extract material (but not always the good flavors)
Finer grind size also increases extraction, but is not an independent variable. There is typically an appropriate grind size for each type of recipe.

This gives us:





Which gives us these insights:
  • Classic Italian espresso machines are hard-wired to give their best results with Italian-style roasted beans (medium dark to dark). FYI: I consider the common "flat 9 bar" profile to be a simplified (and less good) version of the Lever profile. Lever Profile results in typical extraction yields of 19% to 21%, that are the lowest of the 4 recipes, since flow rate is lowest and water contact time is the shortest, with this recipe.
  • Light roasts are known to fall apart quickly and channel during espresso making when using the Lever (or flat 9 bar) profile. This is likely why those whose machines can only that recipe of espresso will tend to compensate by either making Ristretto (short time) shots, or putting a lot more coffee into the basket. If you don't do this, you get very acidic, generally under-extracted espresso, because you haven't appropriately compensated for the lower solubility of the beans you're working with.
  • The Blooming recipe works well on medium to light roast beans, but with ultralight roasts, the puck tends to fall apart at the end of Blooming shots, as ultralight beans don't have enough puck integrity to survive the last stage. Rao tries to work around this by having the last stage flow profiled, so that if the puck integrity fails, at least the flow rate doesn't go super-fast. The long preinfusion demands a super-fine ground. Blooming results in the highest extractions, both because of the long water contact time, but also because this recipe requires the finest ground beans, which also increases extraction.
  • The Allongé recipe works best with ultralight roasts because it demands so little puck integrity, and the fast flow rate require coarse grounds in order to not go over-pressure. The Allongé recipe is the follows the findings from the widely quoted Hendon research paper https://www.sciencedirect.com/science/a ... 8519304102 that coarse grinds, and fast flow, result in relatively high extractions and good consistency. The typical EY of 21%-23% is likely due to the coarser grind than Blooming. But because Hendon didn't use a flow-profiling or pressure profiling espresso machine, his espresso suffered from rapid loss of puck integrity, and so he ended up advocating for shorter duration espresso recipes. By using constant flow (or decreasing pressure) it's possible to use the coarse grind/fast-flow approach but to pull the shot to the normal 30 second duration.
  • Each recipe has an ideal bean roast level. If you use dark roasted beans for any non-lever recipe, you'll likely over-extract it. Light beans on Lever will often under-extract and/or channel.
  • People with manual lever machines are able to make all these recipes, and have long been able to make delicious espresso with light roasted beans. Typically, this has been either a Blooming shot, or they've cleverly made 50 seconds Lever profile shots, thus extending the water contact time over the entire duration of the recipe.

Roast Levels

My definition of roast levels is flavor based, which isn't necessarily that common an approach but here is how I think of them:
  • dark roast: dark chocolate flavor, some "burnt forest" flavors. Often served very thick. Taste profile similar to dark cooking chocolate.
  • medium-dark: a mix of chocolate flavors, both dark and medium, with little (if any) burnt flavors, and some layering of different styles of chocolate.
  • medium: less dark chocolate flavors, but no burnt flavors. Can include layers of different chocolate roast level flavors.
  • medium-light: same as medium (layers of chocolate), but with some fruity (tropical and red fruits are typical) or floral notes added as well. Can have a "milk chocolate" flavor. Taste profile is similar to expensive "single origin chocolates".
  • light: no chocolate flavors. A "well developed" light has other Maillard flavors such caramel, toffee, cooked pear. A "less developed" light roast will not have any flavors arising from caramelization. Fruit, floral, meat, and more. An amazing panorama of flavors is possible with light roasted beans, which is why so many coffee experts favor this roast style.
  • ultralight: intense fruit flavors. Often tastes more like expensive tea than traditional coffee.

This article is a work in progress, and represents my current thinking. I very much would like to discuss it and you're welcome to revise my chart above with your ideas.
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michael

#166: Post by michael »

How many seconds in a short preinfusion 8)

mathof

#167: Post by mathof »

decent_espresso wrote:A unified theory of espresso making recipes

Roast Levels

My definition of roast levels is flavor based, which isn't necessarily that common an approach but here is how I think of them:
  • dark roast: dark chocolate flavor, some "burnt forest" flavors. Often served very thick. Taste profile similar to dark cooking chocolate.
  • medium-dark: a mix of chocolate flavors, both dark and medium, with little (if any) burnt flavors, and some layering of different styles of chocolate.
  • medium: less dark chocolate flavors, but no burnt flavors. Can include layers of different chocolate roast level flavors.
  • medium-light: same as medium (layers of chocolate), but with some fruity (tropical and red fruits are typical) or floral notes added as well. Can have a "milk chocolate" flavor. Taste profile is similar to expensive "single origin chocolates".
  • light: no chocolate flavors. A "well developed" light has other Maillard flavors such caramel, toffee, cooked pear. A "less developed" light roast will not have any flavors arising from caramelization. Fruit, floral, meat, and more. An amazing panorama of flavors is possible with light roasted beans, which is why so many coffee experts favor this roast style.
  • ultralight: intense fruit flavors. Often tastes more like expensive tea than traditional coffee.

This article is a work in progress, and represents my current thinking. I very much would like to discuss it and you're welcome to revise my chart above with your ideas.
I want to take issue with a small part of your roast levels and taste chart. I think you leave out bean characteristics. For example, you characterise light and ultra-light roasts as lacking chocolate flavours. But this is not always the case. I've recently had some Tim Wendelboe Finca Tamara beans.
https://timwendelboe.no/product/finca-t ... cba1185463
As it says in the tasting notes, one of the flavours is sweet chocolate. That is my experience too, and the beans (as measured on my Tonino) are among the lightest I've ever pulled.

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#168: Post by decent_espresso (original poster) » replying to mathof »

I'm not surprised that you can find beans with those flavors, as I did write:
An amazing panorama of flavors is possible with light roasted beans, which is why so many coffee experts favor this roast style.
But I'm going to argue that the "sweet chocolate" flavor in those Wendelboe beans is NOT a product of Malliard reactions, but inherent to the bean itself (ie, an "origin characteristic").

My point in the roast descriptions was to indicate that that light roast beans are unlikely to *create* Malliard (aka "caramelization") flavors. However, it's entirely possible that the beans have that flavor innate to them.

Which is why light roasts are so interesting, as they preserve what's in the bean, as opposed to replacing it with created-through-roasting flavors.

-john

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#169: Post by decent_espresso (original poster) »

michael wrote:How many seconds in a short preinfusion 8)
I can't give you a simple answer. Different Italian machines have been produced over the years to slow-in-general, or ramp-up, the water flow at the start of the shot, in many different ways.

Roughly speaking, I'd say it's typical to see espresso liquid coming out of the puck within 5 seconds, and definitely within 10 seconds, of the shot start with what I call the Lever recipe.

mathof

#170: Post by mathof »

decent_espresso wrote:I'm not surprised that you can find beans with those flavors, as I did write:
An amazing panorama of flavors is possible with light roasted beans, which is why so many coffee experts favor this roast style.
But I'm going to argue that the "sweet chocolate" flavor in those Wendelboe beans is NOT a product of Malliard reactions, but inherent to the bean itself (ie, an "origin characteristic").

My point in the roast descriptions was to indicate that that light roast beans are unlikely to *create* Malliard (aka "caramelization") flavors. However, it's entirely possible that the beans have that flavor innate to them.

Which is why light roasts are so interesting, as they preserve what's in the bean, as opposed to replacing it with created-through-roasting flavors.

-john
Put this way, I agree with your point. I too wanted to say the chocolate in the Wendelboe roast I referred to is an inherent characteristic of the bean (and not an artifact of the roast).