So I've been using a Moccamaster KBGV Select for a couple of months and am running into an off flavor present in my coffee.

I've tried different waters and different coffees and the same flavor persists. The strange part is that the flavor is only there when used 'traditionally' as a drip machine. I've used the Moccamaster a few times for immersion brewing as if it were a Clever dripper and in those brews the off flavor is absent. Strange....

Any ideas what could be causing it? For reference, im grinding on a Baratza Virtuoso at about a ~16 range, making 500mls with 30g of coffee.

I've only used mine for immersion brewing by mistake
Do you get the flavor if you brew with no coffee? I get a slight metallic taste.
(I also found that you need to turn the machine upside-down to drain all the water out if you don't use it for a few months. Enough sunlight can get in to cause mold.)

rjvelasquezm wrote:So I've been using a Moccamaster KBGV Select for a couple of months and am running into an off flavor present in my coffee.

I've tried different waters and different coffees and the same flavor persists. The strange part is that the flavor is only there when used 'traditionally' as a drip machine. I've used the Moccamaster a few times for immersion brewing as if it were a Clever dripper and in those brews the off flavor is absent. Strange....

Any ideas what could be causing it? For reference, im grinding on a Baratza Virtuoso at about a ~16 range, making 500mls with 30g of coffee.

I realize this sounds obvious but have you tried flushing the system with biocaf or urnex? I've found odd flavors are often a sign of some kind of buildup assuming it wasnt always there.
In case yourself or others can make use of this:
https://us.moccamaster.com/blogs/blog/c ... ter-brewer

rjvelasquezm wrote:So I've been using a Moccamaster KBGV Select for a couple of months and am running into an off flavor present in my coffee. . . .

Are you cleaning the basket/filter holder regularly with Cafiza or equivalent? Weekly, for example. Those things accumulate coffee oils that quickly begin casting an off flavor.

So I've cleaned the machine several times to try to solve this with biocaf and descaled with dezcal. Even did a baking soda wash per technivorms recommendation.

For the basket I clean it with soap every other day or so, and last biocaf cleaning was 3 weeks ago, might try just a biocaf cleaning of the basket without cleaning the machine to see if that helps

And I think the remaining water that sits there for 24h or so might be part of the issue. It's just strange to me that it would have an effect when used for percolation but not when used for immersion

How about the filter paper you're using? Important to rinse those thoroughly with hot water (especially if they are unbleached) before you begin. Another culprit may be your grinder - do you regularly clean that?

So im using bleached papers.

In my use case, i set up the mocca the night before and it turns on on a smart plug timer.

I used to rinse the filters but thought maybe them drying out overnight might be the cause of the flavor and so i stopped rinsing.

Also, for this mornings coffee i coarsened up the grind a good bit (from 16 to 24 on virtuoso) and that seems to have helped a lot. Maybe i was overextracting? For reference I generally use 12-16 as poourover range, 9-13 as aeropress/mokapot range.

Dont want to claim victory yet as in the past have changed a variable and it seemingly got better but then went back to the weirdness, but hopefully this is the solution