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The main difference is in the way it makes espresso. Traditionally espresso is extracted with high pressure (9 bar) water. That pressure is build on top of the

The main difference is in the way it makes espresso. Traditionally espresso is extracted with high pressure (9 bar) water. That pressure is build on top of the coffee. When the water passes the coffee and its pressure drops it foams up. This foam is the only way most people can tell they've got an espresso and not some other coffee drink. To be able to build up 9 bar of pressure the coffee has to be fairly fine ground and, most importantly, fresh. Most people do not want to bother with grinding coffee and buy pre-ground. Pre-ground coffee cannot build enough resistance to create any significant foam. So the appliance-level machines, targeted for pre-ground coffee, come with a valve in the portafilter after the coffee. That valve creates espresso-like foam in the resulting drink, which is not much different from a regularly brewed coffee otherwise. Using these machines with a fresh grind is also problematic - they usually miss overpressure valve before coffee and sport a standard 15-20 bar vibro pump. This results in pressure building up way above 9 bar and fracturing the coffee layer, directing all water through narrow channels and missing most of the grounds. tl;dr it's pretty hard to make proper espresso with a Delonghi.

huhtenberg 7y ago
Persistent foam (crema) forms due to the presence of trapped CO2 in the grind, rather than just the high pressure. Espresso grind is special. It's not just fairly fine grind, it's a mix of fine, moderate and coarse grinds that are packed together. If you are to try and use just an uniformly fine grind for espresso, the machine will have very hard time extracting from it - literally a drop a second instead of a flow.
- pandaman 7y ago
  >Persistent foam (crema) forms due to the presence of trapped CO2 in the grind, rather than just the high pressure. If this had been true, you could just toss coffee grounds into hot water and it would foam up. > If you are to try and use just an uniformly fine grind for espresso, the machine will have very hard time extracting from it - literally a drop a second instead of a flow. Really? Any uniformity in grind will block machine? Could you explain physics behind such phenomenon please?
  - huhtenberg 7y ago
    >If this had been true, you could just toss coffee grounds into hot water and it would foam up. Jeez, dude... That's EXACTLY what happens. It's called a "bloom". Here, first hit in Google - https://www.roastycoffee.com/coffee-bloom/ https://www.roastycoffee.com/coffee-bloom/ >Really? Any uniformity in grind will block machine? Could you explain physics behind such phenomenon please? Yes, really. Give it a try. Better yet, read a book on a subject. Something like Blue Bottle's intro into coffee making.
    - pandaman 7y ago
      I wouldn't trust coffee makers as your source of physics and chemistry data. Instant coffee "blooms" too, it's not espresso foam and it's not caused by "captured CO2". Highly uniform ballbearings do not restrict flow any more than other particles of comparable sizes. And, not mentioned by you yet, but my favorite coffee people "fact" - distilled water does not cause more corrosion than tap water.

huhtenberg 7y ago

Persistent foam (crema) forms due to the presence of trapped CO2 in the grind, rather than just the high pressure. Espresso grind is special. It's not just fairly fine grind, it's a mix of fine, moderate and coarse grinds that are packed together. If you are to try and use just an uniformly fine grind for espresso, the machine will have very hard time extracting from it - literally a drop a second instead of a flow.

pandaman 7y ago
>Persistent foam (crema) forms due to the presence of trapped CO2 in the grind, rather than just the high pressure. If this had been true, you could just toss coffee grounds into hot water and it would foam up. > If you are to try and use just an uniformly fine grind for espresso, the machine will have very hard time extracting from it - literally a drop a second instead of a flow. Really? Any uniformity in grind will block machine? Could you explain physics behind such phenomenon please?
- huhtenberg 7y ago
  >If this had been true, you could just toss coffee grounds into hot water and it would foam up. Jeez, dude... That's EXACTLY what happens. It's called a "bloom". Here, first hit in Google - https://www.roastycoffee.com/coffee-bloom/ https://www.roastycoffee.com/coffee-bloom/ >Really? Any uniformity in grind will block machine? Could you explain physics behind such phenomenon please? Yes, really. Give it a try. Better yet, read a book on a subject. Something like Blue Bottle's intro into coffee making.
  - pandaman 7y ago
    I wouldn't trust coffee makers as your source of physics and chemistry data. Instant coffee "blooms" too, it's not espresso foam and it's not caused by "captured CO2". Highly uniform ballbearings do not restrict flow any more than other particles of comparable sizes. And, not mentioned by you yet, but my favorite coffee people "fact" - distilled water does not cause more corrosion than tap water.