Time and Yield impact on extraction

Q&A
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I have read articles on extraction and yield. I understand that extraction goes up with yield and we would like to maximize that in most cases (at least that’s what I understand a message of a “yield” article is even though it’s not always true based on the discussion in the facebook group?). But how does time impact that?

What I am struggling with is that it seems it’s impossible to over-extract when extraction increases because of yield but easy to over-extract when it increases because of time. Could you please point me in the right direction to help me understand this better? Thanks!

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I have found an article on time and I think got a much better idea now. The remaining question — is it possible to over-extract by increasing a yield (keeping everything else same). Does it then become a quest of getting a perfect extraction with maximum possible strength?

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@jimvibe I’m still learning all of this as well, but I would love to give my input and hope someone who has a better understanding will join and set things straight!

From my understanding, there’s more factors that will affect extraction than just yield and time.

So, you could have a great yield (final amount of water + coffee) but still have a very low extraction. This is because grind size (and time, and pressure, and others) also plays a factor in extraction.

Example: You’re making a Chemex. You have a very coarse grind. You run water through your grinds until you’ve reached your desired yield (final liquid coffee). But your time will be very quick (because your grinds were coarse) and thus your extraction will be very low because the water was unable to spend enough time with the grinds.

To answer your remaining question (from my understanding), it is very much possible to over-extract from increasing the yield, especially if your grind size if very small and the time your water spent with the coffee is very long. But, if you see in my example above, with big grind sizes and thus quick times, over-extraction will not occur if you simply increase yield.

It’s hard to understand how the whole thing works unless you consider everything, like dosage, grind size, recipes/ ratios, and brewing methods will also change a lot.

Also, I’ve found time to be better thought of as an indicator than an element in the brewing process. It’s not the best thing to make your coffee by, but it can help show you if you’re making coffee in a consistent manner. It’s really the last thing I’ll look at when making coffee. If everything else is good, and it tastes great, but the time is wonky, I won’t think about it too much.

I know I said a lot. Does this help at all? Definitely ready for correction as well.

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Sorry I’m not answering your question directly, hopefully others smarter than me will, but I wanted to share a tip that’s helped me. I now think about strength and extraction as two separate things I control with each cup/shot I brew. So I’m thinking in terms of both over and under extraction (slightly more objective) and over and under strength (slightly more subjective). When dialing in our house blend this morning for example, I intentional achieved the strength I wanted by slightly decreasing yield. And then got the extraction I wanted by grinding finer/increasing time (keeping in mind that strength would increase because of this as well). Then for the single origin espresso I knew I wanted a lighter strength. I increased the yield to get that and then ground courser/decreased time to get the tasty extraction I wanted (keeping in mind this would decrease strength slightly too).
Hope this example helps and isn’t redundant or more confusing!

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Yeah. You need to mentally separate extraction and strength for sure.

Yield (beverage weight) is almost always tied to time. So increasing one increases the other. And changing that relationship alters surface area (eg grinding coarser for less time).

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Thank you everyone very much for your replies, they are really helpful.

Going deeper is it fair to assume that amount of fresh water coming through a coffee pack correlates with extraction? For example if we fix the extraction time but decrease the pressure — the extraction will be less? Or in other words does the time affect the extraction only because it determines how much water goes through the puck or do some components of coffee really need more time in general to dissolve? I imagine it’s both really but as long as time is in the green (22-35 seconds?) all the components are getting dissolved and time only starts affecting the yield. Am I right?

I like to use Olympia Cremina at home and would be interesting to see the difference between shots of the same yield but using different pressure and as a consequence — a little bit different time. Would it be reasonable to assume that if the time difference between these is just a few seconds, the difference in taste would not be as drastic as if I changed other variables — the yield and a grind for example?