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Dialing In Espresso Extraction Temperature - Page 2

Postby Joejoe on Thu Jan 17, 2013 2:31 pm

Thanks Mitch, I have read this, and I just did again and I think it all just clicked.

So my question is (based on the above link) does temperature changes the total yield of solubles from a basket, or the level of extraction, keeping the yield the same?
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Postby Peppersass on Thu Jan 17, 2013 2:56 pm

Joejoe wrote:D) The overall balance of the extraction, whether it is sour or bitter is based on the flow of the extraction, lungo vs ristretto flows.

As stated, this isn't quite right.

Flow rate does have a big impact on sour/bitter balance, but lungo vs ristretto has nothing to do with it. You can pull a perfectly balanced lungo or a perfectly balanced ristretto. Or, you can pull either of them sour. Or you can pull either of them bitter.

Lungo and ristretto are terms that describe brew ratio ranges, which in turn determine the strength of the shot. The brew ratio is the weight of the dose divided by the weight of the beverage. For example, if your dose is 20g and you pull 28g of beverage, your brew ratio is 71%. That's considered ristretto. In espresso, the target brew ratio is selected based on your preference (some people like really strong espresso, some people prefer milder espresso) and what tends to work best for bringing out the flavors of the bean. For example, some coffees work better when you pull them ristretto because certain desirable flavors get amplified.

For more information about brew ratios, consult Andy Schecter's seminal post on the subject (click here.)

As someone familiar with other brew methods, this concept shouldn't be new: when you prepare brewed coffee, you know that the strength of the cup will be determined by the ratio of grounds to water.

If you haven't already, get a 0.1g scale and start weighing both your doses and shots. That will ensure you are achieving whatever brew ratio you have selected.

Also, if you haven't already, get a bottomless portafilter. When new to espresso, you need to be able to see whether your distribution technique is adequate, and the best way to do that is with a bottomless portafilter.

I wouldn't say that, generally speaking, 14g doses are necessarily any easier to dial in. But some machines are sensitive to dose size and may be less forgiving of distribution errors with larger doses. So go ahead and pull 14g doses until you figure out how to get the best balance and flavor out of them. But bear in mind that the best flavor a coffee has to offer might not be found at a 14g dose. Some blends and SO roasts will shine the most at higher doses.

Small comment on something you said in your OP: grinding finer extracts more for two reasons. First, it exposes more surface area; second, it slows the flow rate, which increases contact time between the hot water and the grounds. This is no different than what happens with brewed coffee.
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Postby Peppersass on Thu Jan 17, 2013 3:12 pm

Joejoe wrote:So my question is (based on the above link) does temperature changes the total yield of solubles from a basket, or the level of extraction, keeping the yield the same?

Not sure about your terminology. What do you believe to be the difference between "level of extraction" and "yield"? I think they're the same.

Perhaps what you mean is "extraction yield" (amount of solubles per unit of water) versus the actual compounds extracted.

As far as I know, we don't have scientific data on exactly what compounds are extracted at what temperatures and in what quantities. We do know that temperature does affect the taste, and specifically the sour/bitter balance, but typically to a much smaller degree than altering the grind or dose. At least, that's what I taste and that's what I see on my VST refractometer. For example, I might be able to nudge a slightly sour shot toward the bitter end of the spectrum by bumping the temperature up one degree. Typically, this will show up as less than 1% difference in extraction yield on the refractometer/MojoToGo.

The best temperature for balance and flavor seems to be a function of the varietal and roast level of the coffee. It's yet another variable, but one that should be adjusted after you have optimized the grind and dose. In other words, it's most useful for fine-tuning.

That said, temperature stability of the espresso machine can be important. If the temperature profile is unpredictable, then you won't be able to pull the same shot consistently, which makes it impossible to dial in.
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Postby Joejoe on Thu Jan 17, 2013 5:35 pm

So peppersas if the ideal TDS of a certain bean is 20% you could in theory:

A) Put in 15 grams of beans in a basket then grind it to a certain grind that let's you pull out 20% TDS of the beans in say 30ml of water, 50% ratio

B) Then put in 10 grams of beans in the same basket and grind it to a certain grind (finer) that would also give you 20% TDS in 20ml water, same 50% ratio. (granted this would be difficult I suspect as it would have to be perfect)

You should have identical drinks, just drink B would be shorter, but this is not the case.

So I am trying to wrap my head around why 50% ratio of 20% dissolved solids can taste different.

And I do have a .1g scale and a bottomless portafilter, I did lots and lots of reading (probably too much) before my purchase. Extracting evenly out of the filter doesn't seem to be a problem for me.
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Postby Joejoe on Thu Jan 17, 2013 6:22 pm

I don't know why this is so difficult for me to get, but I reread jims paper for like to 30th time and think I get it, I am almost sure I get it :idea:

The grind dictates the % of extraction because of particle size. Finer particles get more extracted, coarser particles get less extracted.

Now grind size also effect the ratio of the the drink but it is better adjusted by:

Adjusting the ratio with dose changes, while this does change the extraction % it is only a small amount because you have a longer extraction but with less water to offset it.

Please tell me this is right, if it isn't I am still going to believe it. :shock:

An example would be if you try to make a ristretto with the same dose as a well extracted normale, but with a smaller grind, it would be bitter. If you up the dose a few grams, it will have a nice, strong, slightly bitter sweeter character (we hope)
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Postby mitch236 on Thu Jan 17, 2013 8:35 pm

Joe, you're over thinking this. Just keep pulling shots and experiment with dose and grind and ratios. Leave the temperature alone for now unless it's far away from 200f. After a while you'll get it.

Don't try to over analyze your espresso until you've pulled enough shot to know in your mind what's happening because of what you changed.
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Postby Peppersass on Thu Jan 17, 2013 8:50 pm

Joejoe wrote:A) Put in 15 grams of beans in a basket then grind it to a certain grind that let's you pull out 20% TDS of the beans in say 30ml of water, 50% ratio

B) Then put in 10 grams of beans in the same basket and grind it to a certain grind (finer) that would also give you 20% TDS in 20ml water, same 50% ratio. (granted this would be difficult I suspect as it would have to be perfect)

You should have identical drinks, just drink B would be shorter, but this is not the case.

So I am trying to wrap my head around why 50% ratio of 20% dissolved solids can taste different.

First, your example mixes apples and oranges. Brew ratio is the weight of the grounds divided by the weight of the beverage, not the volume of the beverage.

Second, it's not correct to say, "pull out 20% TDS of the beans". %TDS (total dissolved solids) measures the percentage of your beverage that consists of dissolved solids. 20% TDS would mean that 20% of the weight of the beverage consists of dissolved solids from the coffee. Incidentally, this would be a *really* bad cup of espresso: typical %TDS measurements for espresso should be in the 9%-14% range, give or take a little. By way of comparison, typical %TDS for brewed coffee would be in the 1.2%-1.5% range.

%TDS tells you how strong the coffee is -- i.e., the ratio of dissolved solids to water. But it doesn't tell you whether the dissolved solids in the cup represent an optimum extraction from the grounds (i.e., how much of the bean weight was extracted.)

You may be confusing %TDS with % extraction yield. The latter is the percentage of bean weight that has been extracted. Research studies have indicated that most people prefer coffee made with an extraction yield of between 18%-20%, give or take a little. That's where the sour and bitter flavors will be in the best balance. In other words, you want 18%-20% of the weight of the grounds to end up in the cup.

The % extraction yield tells you whether the coffee is going to taste balanced or not. The % extraction yield can be determined in the lab by dehydrating the espresso or coffee, then weighing the remaining solids to determine their percentage of the starting dose weight. This is a tedious and difficult (and smelly) undertaking, but there's a better way: You can compute the % extraction yield if you know the %TDS, which can be measured with a refractometer, along with the starting dose weight, the starting water weight and the ending beverage weight. VST has computer programs that do this: ExtractMojo and MojoToGo.

Back to your example. Let's restate it using the correct terminology:

Peppersass wrote:A) Set the grind so that 15g of grounds produces 30g of beverage in 25-35 seconds and produces an extraction yield of 19.5%. This will be a brew ratio of 50%, right in the middle of the Normale range. According to MojoToGo on my iPad, the %TDS for that pull will be about 9.7% (beverage weight will actually be 30.2g).

B) Then put 10 grams of beans in a basket with the same properties, adjusting the grind so that you still have a 50% brew ratio (20g of beverage), %TDS of 9.7% and an extraction yield of 19.5%.

In theory, these two cups should taste exactly the same. The only difference is that there's more coffee produced with brew formula A. This shouldn't come as a big surprise. When you brew coffee, you adjust the amount of grounds based on the amount of coffee you want to produce (full pot, half pot, etc.) Typically it's not necessary to adjust the grind because a dose change from a full pot to a half pot doesn't change the flow rate all that much. You might have to make a small grind adjustment between a full pot and for a single-cup pourover, though. The point is, with espresso these adjustments have much more impact on the flow rate and extraction yield.

I said "in theory the two cups should taste the same". In some ways they will. Because the brew ratio and %TDS are the same, they should be of exactly the same strength. Further, because the extraction yield is the same, the acid/bitter balance should taste about the same. But just because the strength and acid/bitter balance are the same, it doesn't follow that the varietal and roast flavors have emerged to the same degree, and therefore the cups could taste quite different to a sensitive palette. This is because these flavors are highly sensitive to the grind setting, which is different for the two different dose sizes. It's also possible that the different thicknesses of the puck, and resulting longer or shorter travel for the water, cause somewhat different extractions.

This suggests that a good extraction depends not only on getting the right percentage of dissolvable solids out of the beans, but also getting the right compounds out of them. While we have a pretty good understanding of the former and how it affects balance, I don't think we know very much about the latter -- i.e., for any given coffee, which compounds in which ratios produce the unique and sometimes subtle varietal and roast flavors we seek.

On your second post (the one after the one with the A and B examples), it's not just grind that determines the extraction yield. It's also the dose. Together, they determine the flow rate. The flow rate has a big impact on the acid/bitter balance.

Grind affects the extraction in multiple ways, which is why it has such a big impact on flavor. First, the amount of surface area affects which compounds will be extracted and in what quantities. Second, the density of the grind, and particularly the percentage of fines produced, affects the flow rate. Dose has a very direct impact on flow rate (thicker puck, slower flow rate), and in turn the acid/bitter balance, but it also can have an impact on the more subtle flavors, perhaps because of the water path through the puck.
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Postby Peppersass on Thu Jan 17, 2013 9:01 pm

One more thing. My previous post said to put the 10g dose into a basket with identical properties. I was trying to point out that the basket has an impact on the extraction, too. In particular, some machines are very sensitive to the amount of headspace above the puck, which may require further changes in the grind to get the same flow rate.
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Postby Joejoe on Thu Jan 17, 2013 11:11 pm

[quote]First, your example mixes apples and oranges. Brew ratio is the weight of the grounds divided by the weight of the beverage, not the volume of the beverage./quote]

Yes, I should have said grams of water, I was thinking the water weight prior to extraction which would be 30g so thank you for the clarification (I have been doing drip for a while).

Second I don't have a MOJO, I always read people taking about TDS but to get the extraction % you have to do some calculation of the TDS, beverage weight, and grind weight. What I was referring to was the percentage of solids extracted from the beans, whatever that is called is fine with me.
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Postby Joejoe on Thu Jan 17, 2013 11:23 pm

mitch236 wrote:Joe, you're over thinking this. Just keep pulling shots and experiment with dose and grind and ratios. Leave the temperature alone for now unless it's far away from 200f. After a while you'll get it.

Don't try to over analyze your espresso until you've pulled enough shot to know in your mind what's happening because of what you changed.


I agree, I have over-analized this to death. I have been following jims rules for dialing in and it works, very well I might add, I just don't understand hoe and why it works 100%. and that bugs me a little, time to let go i guess.

I would like to add that I have had very very good luck getting even extractions with my double and blind portafilters, and have made smooth nutty sweet milk chocolaty shots and aggressive bitter sweet chocolate fruit shots too (and a few sour thin ones :oops: ) all with the same brasil, ethiopia, indo blend. I am having a blast doing it, in fact I am about to go pull a shot for our evening affogato right now, SO DAMN GOOD by the way if you have not tired it!

I am not going to worry about temp, for now at least.

Thanks for your help.
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