Drying coffee pucks in the oven - Page 2

Want to talk espresso but not sure which forum? If so, this is the right one.
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kolu
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#11: Post by kolu »

Andy S. in this debate https://www.coffeegeek.com/forums/coffe ... nes/619509 pointed out that measuring the weight of everything that went into beverage in case of espresso is actually TBS (total brew solids) measurement, not TDS (since there's a lot of undissolved solids present in the cup).

At this point I'm being a bit confused about the extraction (%), extraction yield (%), and so on... Is it the same? And if not - can we compare this number obtained by simple weighting of grounds with the common extraction yield which is by industry standards supposed to be between 18-22 % to get a good cup of coffee?

It's frustrating. A week ago I thought I understand what's going on and now it seems nearly as unclear as when I started reading all the brew control chart articles...

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another_jim
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#12: Post by another_jim »

The post was an argument for the use of refractometers, which measures dissolved but not suspended solids, as a convenient way of deriving extraction parameters. But Andy is more an advocate here than a reporter of the accepted science. Roasting coffee converts some soluble to insoluble compounds and vice versa. For instance, fully soluble sugars at light roasts become partially soluble caramels at darker roasts. But them being suspended rather than dissolved does not mean that the caramels have become irrelevant to taste or smell of the coffee.

The lab standard for all extraction measures is oven drying. Therefore, it is not based on dissolved solids, regardless of the casual nomenclature errors, but on all the solids that get into the cup, and that add to the taste and smell of the coffee.
Jim Schulman

MWJB
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#13: Post by MWJB replying to another_jim »

To be fair the post was advice on dehydration/Yield analysis generally, not using a refractometer specifically.

The lab standard is "extraction yield" (see CBI/SCAA etc, etc...) a good way to establish is oven drying a well filtered sample of the beverage. Extraction yield specifically pertains to Total Dissolved Solids contained in the beverage itself (excludes dissolved mass in the puck/bed) not total brew solids (which as long as they are not excessive, are not necessarily a bad thing and pretty much inescapable in espresso & metal filtered coffee, probably Aeropress too).

There is also a simple way to dial in extraction yield to a ball park range, on the fly - use brew ratios (this is what they are designed to accomplish, there is only a relatively small range of ratios that will get you a common concentration preference at a reasonable yield, many folk find these ratios sit between 1.5 & 1.65:1 for espresso...though you are not tied solely to them), stick to one & adjust grind for best flavour balance...this can be done in real time, shot to shot...rather than waiting for samples to dry (though this would give a degree of confirmation as to what you find).

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#14: Post by MWJB »

On balance, I am not saying you shouldn't dry your pucks/coffee, nor that it can give you no useable guide to a ball-park result, just that specific results may only be directly comparable to others employing the same method (calibrated grinder, basket, etc.). For your own, in-house, evaluation/curiosity, this may not be a big issue.

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kolu
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#15: Post by kolu »

Thank you very much, Jim and Mark.

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another_jim
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#16: Post by another_jim »

MWJB wrote:On balance, I am not saying you shouldn't dry your pucks/coffee, nor that it can give you no useable guide to a ball-park result, just that specific results may only be directly comparable to others employing the same method
Susan, in actual fact, your method is direct, based on fundamental units, and requires no auxiliary assumptions. Therefore, it is the method also used for determining extraction in the peer reviewed food science literature.

Please do not let Mark's condescending remarks discourage you. Mark has a history of posting disparagingly and at excessive length in every thread dealing with extraction. If you are studying extraction and not using the VST refractometer, he feels entitled to bury the thread in nonsense (By the way, the patience of the moderators is wearing very thin on this veiled form of shilling).

Here's the nonsense in this post. Question: How do you filter a puck to remove the non-dissolved solids? Answer: by throwing it away, since it is all non-dissolved solids. Weighing the dried spent grounds is the lab method for measuring total extraction. This figure, not TDS or anything else, is also the gold standard for characterizing extraction. For instance, the weight of spent grounds, and not any indirect method, is used for quality control in canned and instant coffee plants.
Jim Schulman

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GVDub
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#17: Post by GVDub »

Considering the amount of water vapor generated by combusting natural or LPG, is there a difference between drying pucks in a gas vs. an electric oven? How hydroscopic are the grounds when it comes to environmental moisture? Not that I'm ever intending to exercise my OCD tendencies in this exact way, but I thought I'd toss out a variable that hadn't been touched on.
"Experience is a comb nature gives us after we are bald."
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LMWDP#238

SJM (original poster)
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#18: Post by SJM (original poster) »

I haven't bothered to read the last batch of posts, since I got here to see if I've got it too simple or if the following equation doesn't work:

dose weight - dry weight = x
x/dose weight = extraction %

It seems to work when I do my old rusty algebra on it.

My puck from this morning started at 17.5. Dried to 14.3.
17.5-14.3 = 3.2/17.5 = 18.28%

And I think that is an 18% extraction??
or did I miss a step. ?
Understand that I am still not being scrupulous about missing grounds, etc...I just want to see if I'm in the ballpark, and have the procedure right.

Now I'll go and see what I missed.

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#19: Post by SJM (original poster) »

Ah....

I don't know who Mark is, but there's no way I can afford a refractometer (especially after spending for a Compak K-10) so I have to do it in the oven, and ...it is very enlightening.

Hopefully tomorrow there will be a series of pucks to compare instead of just the one.

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#20: Post by MWJB »

another_jim wrote: Please do not let Mark's condescending remarks discourage you. Mark has a history of posting disparagingly and at excessive length in every thread dealing with extraction. If you are studying extraction and not using the VST refractometer, he feels entitled to bury the thread in nonsense (By the way, the patience of the moderators is wearing very thin on this veiled form of shilling).

Here's the nonsense in this post. Question: How do you filter a puck to remove the non-dissolved solids? Answer: by throwing it away, since it is all non-dissolved solids. Weighing the dried spent grounds is the lab method for measuring total extraction. This figure, not TDS or anything else, is also the gold standard for characterizing extraction. For instance, the weight of spent grounds, and not any indirect method, is used for quality control in canned and instant coffee plants.
There was no intention to be condescending, nor disparaging on my part, I'd actually like to think we can discuss these things without making personal attacks. The advice about brew ratios was offered in good faith, I thought a practical, taste based methodology would meet your approval.

Extraction yield is defined by TDS (what else are you measuring to establish yield?), whatever the tool you use to ascertain it. My earlier suggestion was to filter the beverage, not the puck. I can see that weighing dried, spent grounds in an efficient, paper filtered bed has merit, as the filter medium would hold back undissolved solids, therefore the only coffee mass washed out could be dissolved solids. But the OP referred to "pucks" specifically, so I naturally assumed we were talking espresso and metal filter baskets that will pass undissolved solids, making this procedure questionable (purely from a technical aspect). Even so, again I say (without sarcasm, or malice) if you want to dry pucks & take measurements, go ahead, just be mindful of how it may tally against other protocols, though it might be useful for comparative purposes within your own sphere.

I post regarding extraction as it is a subject of which I have some understanding of the mechanics.