I'm just beginning my foray into specialty coffees and my first purchase was an Ethiopian Harrar from a local roaster who listed it on his website as having a "very light" roast. I was extremely excited to get my first taste of "real" coffee but so far every cup I've made has had, to different degrees, had a sour/bitter taste (I'm not really sure yet how to distinguish between the two).

On his website, the roaster recommended "Aeropress 198" as the preferred brew method which I took to mean the temperature of the water, though from the posts on here that seems pretty low for a light roast. I tried using that temperature with 15g ground at 14 on my Virtuoso, with 225g of water. I also followed Nick Cho's recommendation of 40g, ground at 18 on my Virtuoso, with 552 grams of water and a 3:00 - 3:30 brew time. Both methods retained a "sour" taste.

The one way I've found to lessen the sourness is to add some water afterwards, which brings me to my question. When we're talking about a water to coffee ratio (for any method), does that account for the water retained in the grounds? Or do we need to compensate for that by adding water to the final cup? Just asking because I don't think I've ever seen that clarified. Thanks!

I'm unsure from your post as to what brewer you are using? Aeropress or Kalita Wave (Nick Cho's recipe?).

Temperature of the water will drop as it hits the coffee & brewer, so maybe aim a little hotter for drip (94-96C/200-205F)

The water retained in the grounds is more related to brew time, longer brews = more retained. Also whether the brewer drains under gravity, or whether the brew is pushed out under pressure (Aeropress/siphon) has a bearing. I have seen more water retained in truncated cones & flat bottomed cones than in Chemex/Hario "V" cones too.

But, the amount of water retained isn't that critical to what lands in the cup/carafe as regards taste (you can't taste what hasn't landed in the cup). We're only talking a small variation in strength due to variation in liquid retained, which should be fairly consistent for a given brew method. If your brews are sour, grind finer, maybe drop the brew ratio a touch too 59-63g/l? Stick to a consistent dose weight for now, so you are just changing the grind & reducing variables. Keep notes on brew time & whether you have a static bloom (grounds & 1.5-2x water weight sit together, no significant drip through), or whether you are adding larger weights of water (20-25% total brew water weight) from the off & getting flow almost immediately.

At a high brew ratio, or a typical ratio with a lot of retained liquid, sure, diluting with some brew water (bypassing) is an option once you have hit a flavour profile you like, for drip, I personally aim around 7% dose/beverage weight (e.g. 15g dose/0.7 = 214g beverage weight after dilution), for Aeropress/Clever maybe 8%, see what hits your preference. However, this method should really just be used to correct strength/intensity, it may take the edge off sourness, but it isn't directly addressing that particular issue.

Zoran wrote:I'm just beginning my foray into specialty coffees and my first purchase was an Ethiopian Harrar from a local roaster who listed it on his website as having a "very light" roast. I was extremely excited to get my first taste of "real" coffee but so far every cup I've made has had, to different degrees, had a sour/bitter taste (I'm not really sure yet how to distinguish between the two).

...

The movement of some roasters in 3rd wave to a very light roast is often a sour cup, at least for my palate. I had a cup from Heart Roasters when we in San Francisco and I remember just leaving it -- too sour/grassy. I for one don't roast to that level.

Water amount? Some is retained in the coffee grounds. I count that toward ratios, though others may not

Yes. Retained water is baked into these ratios.

Feel free to go by taste. The published/recommended ratios vary considerably from 17:1 to 12:1. Those are very different cups, obviously. Find your sweet spot.

Light roast in an Aeropress - try Tim Wendelboe's recipe - the 'basic' one here: https://timwendelboe.no/resources/brewi ... aeropress/

I used to first brew every coffee that I bought with that recipe to have a consistent basis of comparison. Actually, right now I am drinking that recipe, but with the results of my first-ever roast, and boy, do I like my own coffee! (This is known as "confirmation bias" )

Besides brew ratio, another thing to keep in mind is that temperatures quoted are sometimes slurry temps - the temperature of the coffee+water - and sometimes not. The issue is that a brewing device that hasn't been warmed up is going to cool that water. Chris at Verve (now he is at HoneyCo) shows you some results https://vimeo.com/65761825

Try coffees from around the world, and try different roasters - enjoy the journey!

Ethiopians also tend towards the acidic end of the spectrum. I suggest you come up with a reasonable ratio - I am rather partial to 7 grams coffee per 100 grams of water - and then try a few different beans. I believe it was Boldjava who pointed out that light roasts tend towards sour, and I agree this is often the case. I am in general a fan of this current movement, but it may not be what you are looking for. Right now I have some beans from Compass that are pushed a bit closer to 2nd crack, and they are simply fabulous. Try varying beans by country and degree of roast and compare the taste in the cup. Most South and Central American beans are a dramatic departure from Ethiopians, excepting of course the Geshas which I believe are said to have originated in Ethiopia.

Zoran wrote:When we're talking about a water to coffee ratio (for any method), does that account for the water retained in the grounds? Or do we need to compensate for that by adding water to the final cup? Just asking because I don't think I've ever seen that clarified.

Answering your question completely and succinctly: Yes for all brewing methods other than espresso; because the mass of water "in" is measured and compared to the mass of grinds. No for espresso; as the mass of espresso out is compared to the mass of the grinds.

Rich