Just wondering



by StanD513

50 Comments

  1. MrIceBurgh

    Phase separation the heaviest stuff flows to the bottom

  2. AkbarDelPiombo

    It’s sometimes called ‘the Guinness effect.’

  3. minusmartin

    That there is magic, and it must go inside your body.

  4. NewTown_BurnOut

    Beans probably too fresh and have higher levels of gas in them resulting in mostly crema in your shot. They’re typically best about 5-7 days after roast date. If you want less crema you can grind the beans and let them sit ground for 30-45min before pulling your shot

  5. lonley_trashcan

    Crema is an interphasic emulsion. You’re seeing the solids & gasses coming out of solution.

  6. Pleasant-Pattern-903

    Coffee: the reason I wake up in the morning

  7. 800username

    Toss beans are too fresh; they were roasted tomorrow

  8. HeeBeeGeeBeee

    You’ve poured yourself a lovely Guinness. Enjoy!

  9. What you’re seeing is the phase-differentiated stratification of the espresso’s colloidal matrix, where the denser, oil-laden fractions sediment due to differential specific gravities, while the crema’s buoyant microemulsion rises via the Marangoni effect.

  10. legendweaver

    Bubbles going down? If it’s the same principle as Guinness then what’s happening is this:

    When the bubbles touch the glass they experience drag, as happens when a finger is slid along the surface, and slows these outer bubbles down. At the centre of the glass, the inner bubbles move more easily and are free to rise rapidly, as they naturally do in a liquid, gaining momentum, picking up speed and creating a circulation. The bubbles rising in the middle push and pull the surrounding liquid with them as they rise to the surface. At the top, this liquid flowing upwards hits the surface, and flows outwards towards the glass edge, which then sinks again and pushes the slower moving bubbles at the edge of the glass down. As the outer bubbles descend they eventually get caught up in the rising centre current and then flow up the centre and the circulation continues. This whole process works because the bubbles are very small.

  11. Veeeery fresh beans – from my experience this looks like a beautiful but rather sour espresso

  12. Legal_Jedi

    Isn’t the foam/crema basically losing air and condensing into liquid coffee? Or am I just oversimplifying it in my head?

  13. Why yes I can! Buckle up buckaroo!

    During the roasting process, CO2 builds up inside the coffee bean. The darker the roast increases the amount of CO2 that builds up. The CO2 gas gets trapped in the cellular structure of the bean. Even after grinding there is a considerable amount of gas still trapped inside the beams. This does slowly escape over time. That’s what it is important to put your coffee in an air tight container with a degassing valve.

    Now when you add your grounds to the portafilter doing your pick prep and lock into the grouphead. This create a somewhat air tight chamber that allows you to add up to 9 atmospheric bars of pressure of water in the chamber. This combination of water and pressure dissolves all of the CO2 gas. Once the liquid reaches normal atmospheric pressure (liquid coming out of portafilter) you see that CO2 gas start to fizzle out of solution in the form of crema 🤯🤯🤯

    Soooooo that cascade you see at the bottom of the crema are the micro CO2 bubbles popping. Much like nitrogen releases from solution in a beer and create a nice creamy head. Cheers ☕️ ✌🏼 ❤️

  14. Western-Range-7656

    In beer brewing we call this cascading.

  15. I suppose that there’s a dispersion of CO2 and air in water which is quickly collapsing. This foam is stabilized by the surfactants (lipids and proteins). The visible movement of layers is the gas release into the atmosphere and the water contained in the lamella of the bubbles (walls of the bubble which contains water and are shortly stabilized by lipids. The water of the lamella of collapsed bubbles is moving towards the lower bulk solution as the bubbles colapses. (brown cofffe aqueos solution).

    That’s only my interpretation as chemist, I hope it helps to enrich what you see.

    Sorry for bad english 😀

  16. YogurtclosetRemote47

    Freshly roasted beans, it’s normal. Air out those beans for couple of days to let it releases it’s gas then you’re good to go

  17. chuck_life

    Your beans need a rest, tuck’em in with a blanket and a warm milk and check on them in about a week and they should be feeling better

  18. Ok_Carrot_2029

    Usually the results of a very freshly roasted espresso pull. There are co2 gasses that off themselves while sitting after a roast. If you pull shots shortly after roasting they’ll look like this.

  19. AlexAndMcB

    Gneiss extraction there!
    Can’t take a good shot like that for granite.

  20. One of the best scenes you see in a bar. Mlem mlem

  21. Common-Regret-4120

    Don’t worry that’s what Guinness is supposed to look like

  22. BrewingMatter

    I don’t know what is going on there, but you should throw it away in your mouth.

  23. Those beans straight out of the oven or something??

  24. -Disco_King-

    That is carbonation formed by the pressure made in the espresso machine. The co2 is already in the beans, but it’s pushed into the liquid instead of lifting off the top into the air like most brewing methods.

  25. Sufficient_Novel4334

    You extract a perfect instagramable espresso, enjoy it 👏

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