Brewing pressure and coffee flavour

[Monti]

What difference does it make to the taste of the brew having the OPV valve set at different levels? While brewing if the pressure gets up to 15 bars versus 9 bars how would that affect the flavour of coffee?

Assuming that the grind, dosing and tamping and every parameter is correct and consistent and in every case adjusted to get a 25 ml shot in 25 secs, or 30/30, or whatever you prefer as long as it is the same every time.

[askthecoffeeguy]

Re: Brewing pressure and coffee flavour

A drop in pressure will in theory deliver a longer slower extraction, with a corresponding impact upon taste, making for a rich and lovely crema, with greater depth in the body of the espresso.

This is all good and well in a domestic setting, when youre not pulling too many shots per day

We dropped the pressure of my machine at work last winter, when trade dropped off a bit, and it produced wonderful results, not dissimilar to up-dosing.

When things started warming up and trade picked up, however, we got a very different result, as the machine was not able to keep up with demand, and kept choking the shots!

So we quickly changed it back again!

Based on personal experience Id be more inclined to go for bigger baskets, and greater dose, than less pressure.

Mind you, if I had the kind of machine that allowed me to easily experiment with both, I suppose Id reconsider somewhat.

Cheers,

Pat

[flowta]

Re: Brewing pressure and coffee flavour

What difference does it make to the taste of the brew having the OPV valve set at different levels? While brewing if the pressure gets up to 15 bars versus 9 bars how would that affect the flavour of coffee?

Assuming that the grind, dosing and tamping and every parameter is correct and consistent and in every case adjusted to get a 25 ml shot in 25 secs, or 30/30, or whatever you prefer as long as it is the same every time.

Hi Monti

I found that my Minore II (Uma) was brewing at 13 bar. I had seen good looking shots previously, but when I changed coffees the taste and extractions went to pot. Dropping to 9 bar has seen a significant improvement to both taste (ashiness gone) and consistency, and changing brew pressure is a snap on Uma

Regards

Gary

[Monti]

Re: Brewing pressure and coffee flavour

Thank guys for the response.

Flowta, does the adjusting screw on behind the tray need many turns or a quarter turn would make enough difference for a 1-2 bar drop in pressure?