Here at Subterra, we taste test every batch of coffee. But how? Here is our standard brewing recipe for light roasts.
Especially for light roasts, you will keep the cleanest brightest acidity and sweetness, without bringing the roasty, more 'mediumy' tones.
Here is our pour-over recipe for light roasts:
-Hario V60 Metal 02 Brewer (plastic or ceramic are fine too, I've tested a lot of pour over brewers and keep coming back to the classic V60)
-Hario V60 Papers (the kind that come in the little box like we sell, another blog post on that later)
-Water temp in your kettle at 203F (we are at elevation so 205 at sea level or just shy of boiling)
-30g coffee ground slightly coarse, shaken slightly to create a flat bed of grounds
-this brew is 15:1 h20:coffee by weight. on a 02 pour-over, the recommended coffee range is 20-40g. less than 20g or over 40g and the brewer doesn't perform well. we like a 15:1 ratio but (16:1, 17:1, 18:1) all work great too.
1. Once water is up to temp and you have grounds ready to go, wet your filter and dispose of the water that goes through.
2. With timer running, and brewer/carafe on a zeroed scale, the first pour is 100g water. Swirl slightly vigorously for 10sec, allow to sit.
2. At 0:45, begin 2nd pour, this one is slow circles, spending less time near the edges. Pour slowly and steadily, until the scale reads 300g.
3. Allow to sit until the coffee+water mixture appears to go down about halfway, which should be before the 2min mark on your timer.
4. Generally avoiding the edges but taking care to hit everything, do your third pour, another 150g of water until the scale reads 450g.
5. 5sec after completing this last pour, lift the brewer and give it a very gentle 360-degree swirl (Thank you Scott Rao for this), to clear any remaining grounds off the sides.
6. Your brew should be complete in less than 3min, definitely not longer than 3:30. If it's taking longer, go coarser with your grind until you can get it done in 3min.
Marcus and I were tasting some kenya light gaikundo this morning. I wanted to play with a finer grind size, and got a 4 minute brew. We both agreed that while clean, light, and bright, it had too much 'mediumy' roast tone underneath the acid.
I increased the grind size (bigger particles) from 14.5 to 15.5 on our Mahlkonig grinder, and focused on keeping the brew time under 3min. The second brew finished in 3:15 and we both agreed it was worlds better, with that light and bright vibrancy and no detectable roast tone (ok maybe a LITTLE in the aftertaste but that was it).
The same principles apply to larger brewers and coffee makers. Keep going coarser on the grind until it's as light as you want it. With a longer brew time, you may need to add a little more coffee while keeping the grind coarse to achieve the same goal.
tldr; grind coarser on your light roast pour-overs to try and get it done in under 3minutes, and you'll see the difference!
p.s. in my experience, for larger brewers, Melitta 04 (sold in our store) gets the best drainage. Chemex is great for medium and dark roasts but I can't recommend it for lights, because the paper drains too slowly.