After using the same pressure profile for the last couple months, I decided to start experimenting again and see how different changes affect the end result.

For reference, my old standard:
0:00 - 0:10 -- Preinfusion -- Using 2 ml/s water debit, moderate ramp of pressure from 0 to 3 bar.
0:10 - 0:24 -- Preinfusion -- Cut water debit to 0 ml/s and hold to saturate the puck. (pressure gauge show drops to ~2 bar)
0:24 - 0:45 -- Extraction -- Resume water debit at full power (~8 ml/s on my machine), quick ramp of pressure to 9 bar followed by a natural decline to 6-7 bar.

Experimental Slower ramp:
0:00 - 0:20 -- Preinfusion -- Using 1 ml/s water debit, long ramp of pressure from 0 to 3 bar.
0:20 - 0:24 -- Preinfusion -- Cut water debit to 0 ml/s and hold to saturate the puck. (pressure gauge show drops to ~2 bar)
0:24 - 0:40 -- Extraction -- Resume water debit at full power (~8 ml/s on my machine), quick ramp of pressure to 9 bar followed by a natural decline to 6-7 bar.

The slower ramp during preinfusion results in a significant increase in crema. My normal shots, after a second or two of settling, visually look like 90% espresso at the bottom and 10% crema floating on top. With a slow ramp preinfusion, even after a few seconds to settle, the shot is still a good 80% crema on top and 20% espresso on bottom. The extraction also seems to run faster when using the slow ramp preinfusion.

Pretty shots are great but taste is king, so lets get into that. The high crema shots have a great mouthfeel but are one dimensional and lacking sweetness. I played briefly with grind levels to see if I can dial in the flavor and get the best of both worlds, but so far without luck.

Yes, these tests were done from a modded BDB, but I didn't want to limit the discussion to just BDB owners because there are plenty of other platforms that can do similar extractions.

Thanks for sharing. This full flow control capability is still quite new and there actually aren't that many machines out there that have the degree of control as the BDB does in that. But anyway, new contributions to this space are very welcome.

-Peter

You have a fast flow, after very thorough preinfusion. Your actual extraction is only 16s. This will yield tons of bland crema.

Grind finer, if you have a good enough grinder, or shorten preinfusion stage one until your extraction phase is 25-30s. This will give you better result.