So, I remember reading about this as something that David Schomer complained about some time ago, but that it turned out to be something altogether different from the lower pressure, because, of course, at 9 bar, it doesn't matter that the boiling temperature is lower at 7320 feet above sea level--it's still way, way over brew temperature.
True.
But with any machine with preinfusion, there's a ramp-up. You start out with the water just sort of flowing onto the coffee. My concern is, it seems like this very initial bit is leaving me with spots of burned crema and tainted shots.
Most of the shots I have been pulling, I flush between 4-7 oz; haven't tried more than that yet, as the shots do begin to get sour at 6-7 oz, though again it's mixed with a burnt taste when I sip the dark part of the crema off. Again, my shots are pouring beautifully, it's just that it seems no matter how long I flush, I get a patch of very dark brown in my otherwise pretty golden crema.
Does anyone have experience pulling shots up this high? The boiling point is like 197.2-198.2 here, depending on the weather, much lower than at somewhat lower elevations (temperature is logarithmically related to pressure, I believe). Is there some other common mistake I could be making that would lead to brown patches like I am getting?
