Effects of brew pressure on taste of espresso

Beginner and pro baristas share tips and tricks for making espresso.
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#1: Post by mitch236 »

Not profiling but setting the overall brew pressure on a non-paddle. When I first got involved, I believed 9bar was the "correct" setting. But in the past few months I've been playing with pressures and find that the coffee tastes much better (to me) at 7.5bar.

So my questions

What am I affecting running a lower pressure?
For those of you that play with pressures, do you find certain pressures are better for certain coffees?
How low can I go before I'm no longer making espresso?!! (more of a joke!)


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#2: Post by another_jim »

As a very rough guide, the sweet spot for rotary pumps is 7 to 9 bar. The slower ramp of vibe pumps puts their sweet spot at 9 to 11 bar. But these ranges are also affected by the details of the brew head, particularly the gicleur size and any other flow capacitances or resistances that affect the initial pressure ramp up.

According to Illy labs, the flow rate rate through a puck peaks at 9 bar, and drops at both lower and higher pressures. This means that the classic 25 second shot for proper extraction happen at 9 bar, and that higher or lower pressures would require slower shots for proper extraction. This, rather than taste, may be the reason 9 bar is used as the nominal pressure for espresso.
Jim Schulman

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#3: Post by cannonfodder »

At 7.5 bar you are probably getting very lever like espresso which tends to be lighter in body and crema but it brings out the floral and fruit in most blends. I run my elektra at 8.6 bars if I remember correctly. I would have to put the scace on it to measure again.
Dave Stephens

mitch236 (original poster)
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#4: Post by mitch236 (original poster) »

How much can I trust the built in pressure gauge? I recently replaced it so it is essentially new. I don't want to buy a Scace pressure device just to check!

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#5: Post by HB »

Rather than focus on a specific number, try increasing/decreasing the brew pressure at least 2.0 bar, then decide if you prefer the taste/texture of the resulting espresso. Halve the difference between the previous/current setting and repeat until satisfied.
Dan Kehn

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#6: Post by cafeIKE »

Scrounge an old PF, remove the spout, buy a gauge from eBay, valve and fittings from local ironmonger and voila :

All in, less than $20 and within a pound of the High Price Spread.

NOTE : Liquid filled is not required. Liquid filling damps vibration and lubricates the mechanism

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#7: Post by innermusic »

Should I be calculating brew pressure or backwash pressure? (About 1/2 bar difference on my machine.)
Steve Holt
Trent Hills, Ontario Canada
Vivaldi II, Macap MXK, Baratza Vario

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#8: Post by malachi »

trust your taste
What's in the cup is what matters.

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#9: Post by another_jim »

innermusic wrote:Should I be calculating brew pressure or backwash pressure? (About 1/2 bar difference on my machine.)
What's backwash pressure?
Jim Schulman

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Compass Coffee

#10: Post by Compass Coffee replying to another_jim »

Highly suspect meant with back flush blank.
Mike McGinness, Head Bean (Owner/Roast Master)