You're welcome.

In regards to why some chemicals in coffee dissolve faster than others, solubility is complicated. One might simplify with concepts such as "like dissolves like", meaning that the highly polar solvent (water) will dissolve the more polar coffee extractables more quickly than the less-polar compounds in coffee. Chemicals that tend to make coffee acidic tend to have carboxylic acid groups on then, which are highly polar and more soluble in hot water. Some of the chemicals responsible for bitterness in coffee are acid lactones, where the polar acid is converted to a less polar lactone.

There are many chemicals responsible for flavor in coffee, and the extraction of polar vs non polar, acidic vs. bitter, is not straight forward. That is why i point out that various institutes and such have shown that there is a sweet spot where coffee extraction is optimized. If you wish to argue about efficiency and nutrition and such, you should define precisely what you wish to optimize, what nutrition you are seeking etc.

So, i think maybe i was a little rude and could have used a different tone. My apologies.

If you enjoy immersion coffee, that is great. Your comments on nutrition and extraction efficiency with immersion were what i was referring to.

I think people (myself included) were taking issue with your perceived rationale for the choice. If i may respectfully offer this opinion: It may make more sense just to say you enjoy the taste of immersion brew better, rather than try to argue the technical details of why, if you ultimately do not wish to get deep into the details.

I drink pour-overs because they taste better 9.9 out of 10 times. I have one technique with the Melodrip and all I change it the grind size a few micro notches on my Forté if I decide whether I want to use Kalita filters of V60 filters. And it's really hard to mess up a pour-over with the Melodrip unless you don't have the proper grind size.

My wife got me a fancy looking french press though so I'll be using that once in a while now to compare but so far I don't prefer the taste compared to a pour-over.

Coffee has a WHOLE bunch of factors at play in regards to the chemicals in the bean, their structures and how they react, water as the solvent, the mineral content of water itself that it'd be complicated to set up a controlled experiment to demonstrate immersion vs pour-over.

Efficiency and Theory

rmongiovi wrote:Perhaps the people who make that claim mean something different by the word "efficient" than I do. If I put a tablespoon of sugar in a coffee filter and pour a cup of water over it, after the water has completely drained through there is still some sugar left on the paper. If I put that same tablespoon of sugar in the water and stir for a bit, low and behold all the sugar dissolves into the water. Unless you're preparing absinthe I don't know of anyone who dissolves something soluble in a solvent just by pouring the solvent over it. As you pointed out in your previous post, dissolving takes time. Hence my desire to have better control over that time and my protest over the claim of efficiency.

I think this one is worthwhile fleshing out for the people reading along to get to the bottom of this. Forget all of the ideas about concentration gradients, osmotic pressure and all of that. Just focus on the question: how much water is left in the ground coffee after you brew, and how concentrated is it? Let's assume that it's 2.5x the ground coffee weight. Even if you squeeze, I doubt you could get to below less than maybe twice the weight. For an immersion brew, like a french press, it will be the same strength as the brew. For a filter brew, it will probably be TDS ~1-2%, but let's call it 0 for argument's sake ... I mean it might hypothetically be higher, but since it is new stuff being extracted and stuff that hypothetically shouldn't taste very good, so 0% TDS is a safe assumption.

I'm pretty confident with the assumptions in the above paragraph, but they can, and should, be tested. The retained water stuck in the interstices between the grounds (VST uses the term "liquid retained ratio" or LRR for the ratio of what is retained to the dry grounds) can be calculated by weighing your brewing setup + coffee dry and then weighing it wet, after the extraction, with the interstitial water in it. The last bit of water in a pourover can be captured separately and the TDS measured. The liquid left over in an immersion puck is probably a little trickier to measure, but you could squeeze it and measure TDS or you could flush it out with water and measure the TDS and work backwards. But I'm going to procede with some maths.

Let's say we brew a french press. I'm making up the figures. 20g dry weight, 300g brew water, 250g yield, 50g retained liquid in the grounds. Let's say that we get a TDS of 1.4% strength. 1.4% * 250g brew = 3.5g of dry mass dissolved into the brew. 3.5g of dissolved dry mass/20g starting dry mass = 17.5% extraction yield that ends up in the cup ... but that's wrong - it's not what it will taste like, because we haven't taken into account the interstitial water, which is at the same strength. It will taste like a higher extraction. So let's add the 50g retained liquid in the grounds back into the equation. 1.4% * (250g brew + 50g interstitial water) = 1.4% * 300g = 4.2g of dry mass dissolved into the brew = 21% extraction. That is a huge difference in terms of extraction. 17.5% extraction would be just underextracted on the SCA standard definition; 21% is well extracted, heading towards overextracted. (I'm not saying that to endorse the SCA 18-22% range, but just to give an example of the significance of the difference.) Basically, you have extracted 21% of the ground coffee mass, but you can only get 17.5% of it into the cup. This is a big deal.

Now let's look at an equivalent filter brew. It's sort of a silly thought exercise to hypothesise that there is an equivalent french press and filter brew, since we've just got to recalculate all of the numbers. But let's say that we adjust the grind for equivalence. We could do it two ways. We could adjust to get 250g yield at 1.4% TDS. If we did that, the extraction yield would be 17.5% (it's the calculation above not taking into account the interstitial water). BUT that 17.5% would be 100% (or near enough, because of the assumptions in my opening paragraph) of what had been extracted from the coffee. That means that the 1.4% TDS filter brew will be the same strength as the 1.4% TDS immersion brew, but it will taste less extracted. So now we can also consider doing it the second way; let's say that instead of keeping the strength equivalent, we keep the extraction equivalent. Well, hypothetically we just adjust the grind and extract the 21% into the cup and don't have to worry about the interstitial water.

So, in the above example, you can see that the impact of the retained liquid is huge. In the above example, 0.7g of dissolved flavour is imprisoned in the leftover grounds. That's about 3.5% extraction yield ... it's extracted, but it doesn't end up in the cup.

(For completeness, I should observe that the retained liquid might not just be caught in the interstices; I suppose it could be absorbed into the grounds themselves ... but I'm too lazy to go back and change all the references to interstitial water to retained water/liquid.)

Now, if you've been following along with the above examples, you have probably noticed that I have very carefully dodged saying exactly how much more volume you will get from the resultant extraction yield equivalent filter brew. I doubt that it's as simple as saying you get the additional 50g of water and end up at the same extraction yield at that volume. Presumably this depends on any number of things, like the grind setting, the quality of the grinder, and what is possible with the flow restriction of the filter (eg. the porosity of the paper and the size of the holes, if small). Which leads me to the next section.

Flavour and Practice

Case17 wrote:It has long been recognized that there is a sweet spot where the overall coffee flavor is optimized. Certainly immersion methods are less precise and don't nail the sweet spot as well, but some people prefer the grittiness of it as well. And of course, taste is a subjective experience, so if you prefer the taste of immersion, that's great.

The efficiency point above strikes me as pretty inarguable, but the corollary of it isn't that filter brews will taste better. There's this sort of underlying assumption that it's possible to adjust filter brews to get to whatever extraction level and strength that you want. But this ignores things like in practice you may not be able to get there. You may want to extract more and more from a particular coffee, but with the combination of filter paper and grinder that you are using, you might find that the filter simply clogs.

I'm really not sure what "less precise and don't nail the sweet spot as well" is supposed to mean in the above. I think that it's supposed to mean that you can use a pourover filter cone to better dial in a particular extraction. If that's correct, then it seems pretty clearly wrong to me. You might have a preference for filter over french press, but the french press is clearly more adjustable. You can adjust everything that you can adjust in a pourover filter cone, plus steep time.

I suppose that "less precise and don't nail the sweet spot as well" could also mean that filter cone brews taste better because they do in practice get dialled in better. The thing to look to here would be cafes, but the problem is that, at least around me, there isn't really a commercial immersion brew that's available. Cafes overwhelmingly use single-serve pourover cones with disposable paper filters. There simply isn't french press coffee available in the Melbourne cafe market. I have very occasionally seen french press as an option in a very few US cafes. Of course, as coffee consumers, we are inclined to think that the pros do method x or y and therefore that's the best. Well, there are a whole stack of reasons that are anything but quality that show why cafes would want to use pourover cones. A disposable paper filter is a hell of a lot better to clean up than a french press that you have to wash out. A brew method where you don't have to start it, wait for it to steep, and come back to it, is a hell of a lot better than one where you do. A faster brew method is a lot better than a slower one. And a brew method where, as outlined in the section above on efficiency, you can use say 15-20% less coffee for the same strength, is obviously very compelling. So even if everyone agreed that immersion brews taste better, there are many very good reasons why you would be unlikely to switch to them. The closest thing you will see in the commercial world is probably cupping, which is not a method you can serve customers with, but it's not uncommon to hear coffee roasters lament that brews never taste as good as cupping bowls.

... anyway, to give my subjective take on it and what I actually do, in case anyone is still reading or cares at this point, even after 15-20 years or however long it has been of single serve brewing, I still feel that I haven't come up with a great method. v60 is the defacto standard in Melbourne, and it seldom fails to live down to my expectations. The vast majority of v60 brews that I have had - at cafes that people regard as our best, and all the way up to the highest prices charged per cup on our market - have been lacking in aroma, flat, and seemingly underextracted. I feel like every time I take the same coffee and put it in a cupping bowl, I get 15-20% more enjoyment and flavour out of the same coffee; pourover cones can keep their 15-20% greater efficiency! At the moment, I am experimenting with using a december dripper for longer steep time and finishing it off with a pourover to try to get the best of all worlds. That has been difficult to get right, but feels like a step in the right direction. I'm also going to give v60 another go over my vacation break; I'd be delighted to learn that in fact I've been wrong about it all along and it is brilliant, since the speed, efficiency and ease of cleanup remain compelling selling points even at home.

If you're reading this thread and thinking about what you should do at home, the great thing about coffee is that there is often low-hanging fruit of stuff that you can just do and try. You don't have to jump all the way to the final solution, and you don't have to spend money to learn more. If you haven't, I think you really should try a cupping brewing method. The grind setting is, of course, the most difficult thing to get right. If you have a filter cone, try the same grind setting for argument's sake. Grind directly into a mug, pour in boiling water, wait 4 minutes, break the crust with a spoon so that the grounds sink, skim off and discard whatever floats, wait another 10 minutes, then start drinking. A few things are quite peculiar about this brew method. It is suprisingly clean, and devoid of sludge and mud. It is usually surprisingly low in TDS/strength ... yet surprisingly high in aroma and flavour. It also takes a surprisingly long time for the brew to start to taste overextracted. It sort of underscores that agitation clearly plays a large role in what happens in any brewing method. You could, of course, filter this off. James Hoffmann's french press method is one way; I think I'd possibly consider plunging down and stopping before the filter touches the ground coffee, to avoid agitation. You could also pour through a pourover cone to filter, though, again, I'd try to avoid agitation. You might love this method, you might hate it ... but at least you won't have to spend money speculatively to find out!

I use a plastic V60. Don't really need to overcomplicate things with pour over. Having said that, I have tried brewing with a Chemex only once many years ago, and now I think it would be interesting to try to get used to the larger drip hole after using the V60 for a long time. I imagine it would be a whole new challenge.

Plastic v60 is the way to go, as it doesn't sink heat.