I'm seeking the expertise of those here on what parameters I might look to change to remove a tomato like smell and taste characteristic from pour over/immersion brewed cup. I'm using Intelligentsia's Kunga Maitu Kenyan, 8 days past roast, which is described as being sweet and complex with flavors of pineapple, pink grapefruit, buttered rum, and hibiscus. I'm using a Bonavita Immersion dripper, PID goose-neck kettle, and a Hario mini-mill. Coffee/water is weighed to 1:15 ratio.

So far, I've only been able to brew a very acidic and under extracted sour cup due to what I presume is too low of water temperature (before I received the PID kettle) using a full immersion method w/ 30-45s bloom, 1:30 immersion, and 1:30 drain. This cup smelled great, but was just a little too tart/sour in the back of the mouth.

I've also tried keeping the drip valve half open to get more of a pourover effect at 3:30 total brew time, :45s bloom, and 206F on the kettle, and this is where I'm getting that tomato paste aroma and flavor. I'm not even sure what flavor characteristic that would be classified as, but I'm pretty sure it's not the flavor the roaster intended.

My question uses this scenario as an example, but is actually much broader than this specific coffee, as I'm still pretty new to brewing coffee, and how to manipulate it to extract the best flavors. Can the same principles used to dial in flavors for espresso be applied to brewing? My first guess is that maybe I should lower the brew temperature and/or go back to the immersion method since that seemed closer to the intended cup, but I thought I'd see what I could dig up here so the trial and error can be a little more purposeful.

It sounds like you are thinking about this the right way.

Are you heating up the brewer before adding coffee? Aesthetically, the nice thing about the Bonavita immersion dripper is that it made out of porcelain instead of plastic. But all that thermal mass is a liability of you don't bring the device to temperature before brewing.

Otherwise, using too large of a grind size would under extract the coffee in much that same way that low brew temperature would.

First, of all, I would skip the blooming step, as there is no need for it with an immersion brew. Just add all the water, stir to combine, and then let it be.

If your brew is too sour, then the standard remedies are all ways of increasing the overall extraction: Brew hotter, grind finer, or steep longer. I agree that pre-heating the brewer is essential if you haven't been doing that.

And finally, it may just be that you don't like this particular coffee very much. You said your pour-over revealed some tomato, but you didn't say whether it was otherwise balanced between bitter/sour and sufficiently sweet, so it is hard to tell if this is a quality inherent in the coffee or not. Many fine Kenyans can have some sweet tomato in the fragrance of the dry grounds, and sometimes it will show up in the cup as well. Some of us like this quality, while others disagree. I'd play around with higher extractions to see if that helps you discover something you love in this coffee, but if it doesn't, you may just want to try brewing something else that is more to your taste.

Thank you for the replies so far.

I do pre-heat the brewer and rinse the filter, and the grind is on the finer side, fine enough that when using the brewer as a pour over is yielding a 3:30 extraction time (including bloom time). I have considered that maybe this coffee just isn't for me, but being that I am new to brewing I figure this will serve as a good learning experience in general. Plus, pineapple, grapefruit, and buttered rum sound good!

Where I'm a bit confused is that I've gotten the sour, under-extracted flavors out of this coffee, with presumably what is too low of a brew temp (this was before I had the PID kettle, and was just using a stove top kettle to boil and then rest for 20-30s). So, with the addition of the PID kettle, I set it to 206F, and that's when I'm getting the tomato flavors and aroma. Where I'm lost is if I should try a higher or lower brew temp. Naturally, my guess is to go a touch lower, to maybe 203 or so, thinking that the brew temp was lower than that when I was getting the too-sour taste, yet you guys are suggesting that the tomato might be due to under-extraction in which I would potentially need to increase temp (although I realize I might need longer brew time or finer grind).

In reality, I can try both and see what happens, but I always like hearing what you guys have to say and learning from it, or seeing if my logic is flawed. Thanks again!

I thought your drawdown times sounded like the were in the zone.

You might try 203°. A lot of the (good) coffee books I read recommend higher brewing temps than what I see baristas using in the field. That suggests to me that cafes are more concerned about over-extracted flavors than under-extracted.

The most onerous stuff I get in the cup is due to brewing temps that are too high. In fact, I can sometimes tell if the brewing temp was too high by smelling the grounds. Some tastes are meant to remain locked in the bean, and tomato paste sounds like one of them.

I love the Bonavita Dripper and I like to brew at 200f. Go figure!

Thanks for the replies! I did a pour-over cup this morning with the dripper's valve open and 202F water, 1:15 ratio, stopped it at 3:30, and the tomato smell went away, as did almost all of any flavor (of any kind), still don't have the sweet fruits the roaster lists - I'm starting to concede that this just isn't the right coffee for me - it was received as a gift, so no harm there. I might try backing off the grind a touch - at the 3:30 mark the last bit of draw down was getting choked off. So between a slightly coarser grind and maybe even a little lower temp yet again (200F), I'll finally get a good cup as the bag is almost gone.

Nonetheless, it was a good learning experience, and I think it's safe to say that the tomato paste smell and flavors were due to too high of a brew temp and/or over extraction, thanks again for your help.