It’s not a law, but the rule of thumb is +10°C _doubles_ the rate of chemical reactions*.
If we take the ‘typical’ rule of thumb for coffee brew water temperature, we get:
195-205°F = Δ5.6°C ∴ ±~56% change in reaction rates, and every 1°F represents approximately 5% change in the rate of reaction. Think about this when your brain are hyper-focused a scale while trying to get your 350g brew water weight precision down to 1.0g (which is 0.2%).
*-the classic rule of thumb on rules of thumb is that thumbtimes it’s true, thumbtimes it isn’t.
Summary & Links:
The PRESS RELEASE we read on the show
YouTube link: Bree (the most popular Barista in the Pacific Northwest)
ICE Coffee “C” Futures
“At The Cupping Table” with Trish and Mie from 49th Parallel.
Ethiopian Coffee “BladderGate” (more reading) LINK: Portafilter Podcast #58 interview with Getachew Mengistie
The future of the Keurig single-cup coffee system (LINK: SF Bay Coffee OneCup)
Our Top-5 list of the Most Fascinating Things in Specialty Coffee in 2011
Duration: 1h 31m 19s
Critical analyses of coffee brewing methods involves taking a close look at what happens to individual coffee particles through the course of the brew. Every brew method involves three notable steps: Wetting, extraction, and separation. For some methods, extraction and separation happen mostly simultaneously (i.e., drip brewing). For other methods like cupping, french press, or Clever dripper (among others), extraction happens in a relatively static environment with separation occurring only (or mostly) at the end. It’s important to note: separation always includes extraction, often with an accelerated or more forceful dynamic.
During such methods, the fact that separation of grinds and brewed product (the beverage) happen at the end of the brew also means that the separation is occurring when the risk of over-extraction is high. You could stir the hell out of a brew at the beginning, but the cross-over into over-extraction usually won’t happen until later in the brew time.
MOST french press brews out there in the world are woefully underextracted, and not representative of this brew method’s potential. Worse, high-sludge content due to sloppy or poor technique, contribute what can only be called “false body,” that is, mouthfeel that comes from the super-fine coffee particles in the brew, rather than from the coffee itself. This is even further exacerbated by very dark roasted coffees, for which the roasty-toasty-burnt flavors are so soluble that they dominate an otherwise weak and underextracted brew. Grinding approximately for drip and brewing for under 5 minutes is generally leaving desirable flavors out of your brew.
So to make a delicious french press is to make a properly extracted french press. To do that, there are three key elements to consider:
1) proper wetting
2) the static environment
3) the separation dynamic
*1) Proper wetting*
In order for extraction to happen efficiently, the coffee particles must be free of gas, and surrounded by water on all sides. If coffee grounds are floating, or intermixed with gaseous bubbles, one or both of these requirements aren’t met. Gentle stirring, a prolonged pour of brew water, or a light plunge of the filter screen will help fully wet the coffee.
*2) The static environment*
A static extraction is both good and bad for the quality of the beverage. It’s good because certain brew methods can inflict too much kinetic energy (read: turbulence) on the coffee grounds which causes the surfaces of the coffee grounds to extract too quickly. A more static environment allows the solubles to diffuse more naturally into the brew water. Conversely, a static environment can cause the water around the coffee grounds to become over-saturated with solubles, which slows down the osmosis effect necessary to get the solubles out of the coffee particles.
So the solution is to extend the brew time beyond what’s typical for a drip-style brew, and grind significantly coarser. If an ideal drip-grind peak particle size is approximately 800μm (0.8mm) in diameter, something around 1200μm (1.2mm) is great for french press. Why?
The longer brew time is necessary to correspond with the static brew environment. However, since a longer brew time would normally lead to over-extraction, reducing the overall surface-area to coffee-mass ratio helps reduce the proportion of over-extraction in the brew. Remember, because coffee grinds are not truly uniform in particle size (unless we physically separated them and removed outlying particle sizes), a coffee brew is always a mixture of “good” brew, overextraction, and underextraction. The overall better-quality brews are simply higher-proportions of “good’ brew than not. The smaller-than-peak grinds will overextract. The larger-than-peak grinds will underextract.
So if a drip brew with 800μm grind sizes is a 4-minute brew, and a french press is a 6-minute brew, and we wish to reduce the surface-area-to-mass ratio of the coffee grinds accordingly, we come to a 1200μm grind size.
Obviously a coffee particle is not a sphere, but the results are the same if you use any shape as a model:
Volume of a sphere = 4/3 * π * radius-cubed
If diameter = 0.8mm, volume = 0.268 cubic mm
If diameter = 1.2mm, volume = 0.905 cubic mm
Surface area of a sphere = 4π * radius-squared
If diameter = 0.8mm, surface area = 2.01 square mm
If diameter = 1.2mm, surface area = 4.52 square mm
Volume / Surface area
@0.80mm, 0.268/2.01 = 0.133
@1.20mm, 0.905/4.52 = 0.200
∴ 0.133 : 0.200 :: 4 minutes : 6 minutes
So grind coarse (about 1.2-1.5 mm diameter peak grind), and 6-8 minutes. Yes, really. Not only does this coarseness work in consort with the brew method, grinding this coarsely results in a smaller proportion of extra-fine particles.
It may help to very-gently stir-up the coffee grounds at the end before you plunge, so that the flavor compounds that diffused out of the grinds sitting at the bottom of the glass (which you’ll have if you were successful in your wetting) will be added to the mixture, rather than just sitting at the bottom of the glass.
*3) The separation dynamic*
The separation between grinds and resulting beverage should always be as gentle and low-kinetic-energy as possible, especially for brewing methods with a primarily static brew dynamic like french press. The particles at the end of a brew have already released the desirable flavor compounds. If you forcefully stir or squeeze the coffee particles at the end of the brew, you’re much more likely to add overextraction-flavors to the brew than otherwise.
So plunge gently. If you feel even the slightest resistance due to a layer of coffee grinds building under the plunger, back off gently and press on. If you forcefully press grounds downward in the glass with the plunger, you’re forcefully extracting those grounds. So don’t do it. You’re also forcing more super-fine coffee particles (a.k.a. fines or sludge) through the mesh if you plunge hard.
Otherwise, you know what to do. 60-70 grams of coffee per liter of water, and ~200°F (±5°F) brew water to start. Final point: technique (or method) is important, but quality of coffee, quality of grinder (uniform as possible), and quality (clean) water round-out the four pillars of great coffee brewing.
Let me know in the comments how this works out for you!
UPDATE 2014: This blog post refers to the previous sensory skills test. It was revised in 2013 to correct the Part 3 “trick question” issue. Now the concentrations from parts I and 2 are indeed carried over to Part 3. Leaving this post up for reference, but do understand the update. Mmmkay?
The SCAA Sensory Skills Test is out there. It’s touted as an objective test of your taste acuity, removing olfactory (aroma) to focus on your papillae. The problem is, the test is poorly designed and those who have the acuity often still fail. It was once required to pass this if you wanted to be a World Barista Championship taste judge, and it’s still part of the CQI Q-Grader exams. If you’re going to take this, study this guide first.
Part 1: Three different strength levels of Salt (table salt NaCL), Sweet (table sugar, sucrose), and Sour (citric acid) are presented in groups, for a total of nine solutions. Identify the strengths in order for each group (i.e., Salt 1, 2, & 3)
Part 2: The nine solutions from Part 1 are presented in random order. Identify the type (salt, sweet, sour) and the strength (1, 2, & 3).
Part 3: Eight mixtures of Salt, Sweet, and Sour are presented. Four are 2-part mixtures, four are 3-part mixtures. Identify each component type and the strength in each mixture.
If you can’t pass the test Parts 1 and 2, you’re on your own… you might be a non-taster and may want to consider this in your career choices.
Part 3, depending on how it’s presented to you, is likely a TRICK QUESTION.
The “trick” is that there are eight mixtures, four 2-parters and four 3-parters. That’s all fine. The misconception is that when you combine the tastes, your palate is confused by the mixtures somehow. THIS IS NOT TRUE.
THE PROBLEM :
What most instructors don’t tell you or don’t know themselves (and that the materials don’t explain), is that if you have a 2-part mixture, each component is now HALF the strength it was before. If Salt-1 is 1.0-grams-per-liter, and you dilute it with one part of Sweet 2 solution, the resulting solution is now 0.5-grams-per-liter… because the other half is the Sweet solution.
THEN, for THREE-PART solutions, each component is diluted by 66.6%. The 1.0 g/L Salt-1 is now 0.33 g/L. In other words, a “Salt-2″ will taste WEAKER in a three-part solution, than in a two-part solution.
The written instructions DO tell you to FIRST, separate the solutions into two-part and three-parters, and then analyze the components. This is a good tip. However, if you don’t realize the dilution is happening (which, frankly NOBODY does), then you’re going to find it much more difficult.
THE TIP :
The best advice is DO NOT use the test Parts 1 & 2 as any sort of reference except for calibrating yourself to the relative relation between various tastes and strengths. In other words, Parts 1 & 2 will give you a general idea about how different the strengths are from each other, and about what each component tastes like. Part 3 should be considered a COMPLETELY NEW test.
In other words, if during Part 3, you search for the Salt-2 or Sweet-3 or Sour-1 that you remember from test Parts 1 and 2, you’ve been tricked. They don’t exist anymore. Forget those. Write them a card if you miss them, but let them go.
First, taste each solution and for each, ask yourself, “Do I taste salt? Do I taste sweet? Do I taste sour?” and check each off on your worksheet. Then, separate the two-part solutions from the three-part solutions. You should have four of each. THESE TWO GROUPS SHOULD ALSO BE CONSIDERED SEPARATELY FROM EACH OTHER.
Start with the two-part solutions now. Find the strongest component you can find. It might be a sweet, sour or salt. This is going to be a level-3 strength. Now recalibrate your brain to think of that as the level-3, and extrapolate downwards in your mind, re-imagining the level-2 and level-1 strengths. There will be at least one or two level-3 components of some sort, but there might not be a level-3 for all three components. Don’t over-think it, but proceed through each solution.
Then, erase that experience from your mind, and proceed to the three-part solutions. Same thing: Find the strongest component you can find. It might be a sweet, sour or salt. This is going to be a level-3 strength. Now recalibrate your brain to think of that as the level-3, and extrapolate downwards in your mind, re-imagining the level-2 and level-1 strengths. There will be at least one or two level-3 components of some sort, but there might not be a level-3 for all three components. Don’t over-think it, but proceed through each solution.
This will set you up for the best chances to pass the dreaded Sensory Skills Test. Good luck!
Summary: World Coffee Events/SCAE Competition Wrap-Up, “The SPRUDGE Radio Minute,” we talk about the recent Twitter debacle, “At The Cupping Table” with Trish and Colleen, and we answer a couple of calls and discuss grinders and hipsters in coffee.
Duration: 1h 16m 10s
I wasn’t there, but I watched online. Looked AMAZING from where I was sitting! Congrats all, especially Alejandro!!!
By no means the most deserving of accolades, but want to highlight the first live audio commentary pilot programming, courtesy Peter Giuliano and James Hoffmann. People have complained for years that the competitions aren’t very engaging to watch. What Peter and James added was a lot of what’s missing, and it was a great peek at what’s possible in the future. LOTS of notes for WBC 2012 Vienna!
That is all.
Duration: 52m 58s
As the manual-brewing trend has developed over the past few years, various coffee-making tools have emerged on the market. Some are classic methods that have been around for decades, others are brand new to the market (often in more ways than one), while still others are new versions of older methods.
When critically analyzing filter-coffee brewing devices and methods, I usually start with a set of assumptions:
1) Materials and design that promotes a stable brew temperature is best
A brewing environment will, for most brew methods, lose temperature naturally as heat dissipates to the surrounding air and materials that it comes in contact with (the exceptions are methods that add heat energy during the brew, such as vacuum/siphon or machine-drip). Certain materials serve as effective insulators (such as air and plastic) that slow this temperature loss, while others can serve as “heatsinks,” which by their nature will transfer heat outward (glass, ceramic, metal).
So the material that the brewing space comes into contact with matters. Even if you “preheat” a dripper, it’s going to be fairly impractical to actually get it to a high enough temperature to mitigate its heatsink action during the brew. The alternative is a design that reduces the physical contact that the brewing space has with the dripper material.
2) a design and method that promotes even extraction is best
When brewing coffee, “even extraction” is a simple idea that, in practice, is actually extremely complicated. In manual brewing it’s really managing the amount and degree of unevenness. Because at some point, you need to separate the coffee grounds from the resulting beverage, it’s pretty much impossible to achieve a truly even extraction.
For manual brewing, “even extraction” can be best managed by optimizing pour, flow, and geometry.
By “pour,” I’m referring to the action of pouring water upon the coffee bed. I believe that reducing the “pour” down to ZERO should be the goal when brewing drip coffee. To explain this, let me explain “flow.”
By “flow,” I’m referring to the action of water flowing through the coffee bed. The flow of water through the bed (due to gravity) creates a lot more effective turbulence than most would assume. Remember, the coffee grounds are being held in place by the filter, which means the water is flowing past the grounds. When do you directly experience more turbulence: when you’re floating in an inner-tube down a river, or when you’re trying to stand still in that river?
So if the coffee bed is experiencing a certain amount of turbulence due to the flow of water, what about the pour? How does the amount of extra turbulence you create by pouring water on the top of the coffee bed change the evenness of turbulence? How does the depth of the coffee bed affect this unevenness?
This is why I stated that reducing the “pour” down to ZERO should be the goal when brewing drip coffee. If you’re still with me, you might be realizing that NO brewer available actually works this way.
By “geometry,” I’m referring to the shape of the brewing space, and how water flows through the bed and through the system.
A conical or wedge-shaped geometry will not brew very evenly. Just like a piece of meat won’t grill evenly unless its top and bottom run parallel, the shape of a brewing space is very important.
Okay. Those are my assumptions. Moving forward.
This is why I’m encouraged by these two brew methods we’ve started importing from the KALITA company in Japan.
The Wave Series drippers provides a flatter bottom geometry than the others on the market, with the brew water flowing down through the bed and out the bottom. This first quantity are Kalita’s 185-size, which is comparable to the 02-size for Hario V60 drippers and a Melitta #2. We will soon be bringing in the smaller 155-size drippers and filters. Why smaller? The smaller the filter, the smaller the distance of your pour.
The other unique design feature is the Wave filter. Because of the wavy-sidewalls, there is minimum contact between the brewing space and the dripper sidewalls. The filter actually “floats” in the dripper and doesn’t touch the bottom of the dripper.
The Kantan Drip from Kalita is something truly special. Their main downside is that they only hold about 16 grams of coffee grounds. More than that, and you’ll be overflowing after the bloom. Other than that, they’re pretty badass. They’re flat-bottomed as well, but because they’re so small, you can actually pour with zero pour distance: you can actually place the tip of your pouring kettle on top of the bed of coffee as you pour. It’s really as even as drip brewing gets, and in a origami-type fold-out design, which starts and stores flat. Oh, and there’s effectively no “dripper” involved to steal heat.
I wanted to introduce these to the North American market because they have unique qualities which I think make them viable options for the pourover enthusiast. You may notice that they’re a little more expensive than some of the others out there, but Kalita is, both here and in Japan, a premium product designed by and for coffee-professionals. What that means to you and me is that they make it easier to make consistently good quality brews. Isn’t that what we want?
Summary: Mark busts Nick’s chops, SCAA Chronicle article “Important or Self-Important,” the inaugural SPRUDGE Radio Minute, and the first in a multi-part exploration of the coffee C-Market with Peter Giuliano from Counter Culture Coffee.
Duration: 1h 07m 49s
After a three year hiatus, the Portafilter Podcast is back for all the good coffee-loving girls and boys! New co-host, new feel, new and improved! This episode, we talk about the Good Food Awards, the USBC Brewers Cup competition, and the volatile NYBOT coffee market.
OUR CALL IN NUMBER is 805-727-3638.
42 minutes and 16 seconds – MP3 format, 38.7 MB
Click “Portafilter Podcast” link at the top of this webpage for more info.