Hello fellow HB,

I was dialing medium dark (more on Vienesse) coffee beans on single group slayer and it turned out to be sinkshots.
Awful bitter and... just unpalatable for me. According to the local roaster the tasting notes would be around: hint of palm sugar, dark chocolaty finish.

I tried pulling shots with 20s pre brew timer, at 91C and the brew time was about 20s on a brew ratio of 1:2. Does the prebrew actually make the shot awfully bitter? Well I did try the traditional pull (after adjusting the grinder coarser 2/3 times) and it tasted wayyy better. My thought was that the longer the medium dark beans touched the hot water, the more the bitter flavor gets extracted.. Should i maybe try pulling ristretto on that?

Any single group owners experiencing the same thing on medium dark beans?

Thanks

In short, yes.

The point of the low-flow prebrew is to allow finer grind and higher extraction from light roasted coffee.

To make good espresso from darker roasts, you will need to decrease temp, grind coarser, updose (usually) and either eliminate or drastically reduce the preinfusion step. You can increase the flow rate for preinfusion with the needle valve, to allow a little bit of prewetting if you like.

Hope this helps,

Mike

Ahhh... I thought so. Thanks for clarifying those Mike! I will play around with the flow rate for the pre-infusion tomorrow.