Excellent reply Jeff. Ill alter the Synesso and see if I notice a change.

Thank you.

Talking about peak is also interesting. The shots I had with a rapidly declining 5.5->0 bar on an Aplimont MiniGaggia were certainly different from flat ~6 bar shots from the Robot. Perhaps thinking in terms of average pressure is actually not a bad idea.

I deleted a few sentences from this post as they do not represent what is important to me in this post. The next post still reference the most offensive part if you need to know, but I really would rather discuss what is still in this post:

I appreciate James for widening the audience, maybe we are lucky and he draws some food chemists into this hobby

My take is...
Given that a pressure increase has some physical effects I would expect that some chemical processes should be speeded up with higher pressure and maybe there are even some chemical processes that only occur when a certain pressure is reached.

I would argue that espresso actually does taste better when brewed at a specific pressure. I would just think that this is a specific pressure for each roast. Hence you can not generalize coffee gets better at pressure X.
Maybe it is even a specific pressure for different phases of the brew. Maybe for mechanical reasons like low pressure during preinfusion seems to benefit the puck integrity. Or maybe chemical reasons like a certain process at a certain pressure should take place only after some other process has completed, e.g. first 6 bar for until X has completed and later 8 bar.

coffeeOnTheBrain wrote:I generally appreciate James videos, in this case he might have overshot with his simplification in a sense that he actually spreads fake facts.

Could you quote his "fake facts"? I didn't hear any.

There was some generalization that he disclosed to begin with but given his experience, which includes designing espresso machines, I think your statement seems quite dramatic and does not correctly characterize what he presented.

I edited my initial post to make it less dramatic/ offensive.
If you don't mind I really rather not discuss that part as there are other parts in my initial post that I deem way more interesting. If it helps any, I take back the "fake facts" part or maybe we can agree on "it was not everything that there is to know about pressure".
What do you think about chemical process being speeded up at different pressure or maybe not even taking place at lower pressures?

RapidCoffee wrote:When I reproduced this experiment for my DE1 review, I also saw higher flow at 8 bars than 9 bars. I don't know if this is of great significance. IMHO the interesting thing is that flow peaks around 8-9 bars and then declines.

most machines measure at the pump where the decent measures at the group. I suspect there is a drop from the pump to the group. I seem to remember Rao commenting on this that 9 bar at the pump gets to pretty close to the ideal pressure for maximum flow once it gets to the group.