Ideal crema is dark, light, or golden?

Beginner and pro baristas share tips and tricks.
psyclus

#1: Post by psyclus »

Hi!
Im kind of new to espresso, well not new, but not as educated as most of you are. :)

I see a lot of espresso, and latte-arts with this dark-reddish crema. I tried different coffee blends, maybe im not trying enough. But im only getting golden brown.
Any tips to make my crema darker?
This is mostly because i want to make some nice contrast rosettas and such. :)

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another_jim
Team HB

#2: Post by another_jim »

The same blend will go from dark brown to a pale golden colored crema depending on water temperature, hotter being darker, cooler lighter, colored. In fact, a low tech diagnostic of shot temperature is that dark brown crema means too hot, cream colored, too cold.

Also, crema gets lighter during the course of the shot, no matter what the temperature, so the rim of the cup will tend to be darker than the center.
Jim Schulman

psyclus

#3: Post by psyclus »

so, by this you're saying that my golden brown is the right temperature espresso? Its not pale, its just not as dark as i want it to look for the rosettaes..

Thank you for replying:)

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another_jim
Team HB

#4: Post by another_jim »

Not necessarily, blends taste different at different temperatures. The crema color and the taste aren't necessarily both prettiest at the same time. I'm saying that once you have a blend dialed in, you can somewhat gauge whether you've hit the temperature right by the color of the crema.

For any sort of milk drink, in general, a hotter extraction than you'd use for straight shots is best, since the added bitterness will play nice with the milk. So the darker colored crema is automatic if you can tailor the shots properly.

If you have an HX machine, you can darken up the crema by flushing a second or two less, if you have a home machoine, you can achieve the same effect by kicking on the steam button for the first few seconds while pulling the shot. If you have a double boiler, you're either stuck with whatever is dialed in, or you can wait for however long it takes to raise the temperature (raising is usually fast, dropping it takes longer or a lot of flushing).
Jim Schulman

psyclus

#5: Post by psyclus »

thanks for all your help :) It worked using the steamer, when i pulled the shot :) Got a darker crema :)

King Seven

#6: Post by King Seven »

another_jim wrote:The same blend will go from dark brown to a pale golden colored crema depending on water temperature, hotter being darker, cooler lighter, colored. In fact, a low tech diagnostic of shot temperature is that dark brown crema means too hot, cream colored, too cold.

Also, crema gets lighter during the course of the shot, no matter what the temperature, so the rim of the cup will tend to be darker than the center.
Surely this presumes a certain type of roast and a certain quality of extraction. Crema is merely a foam of the coffee underneath so the colour of the crema is entirely dependent on the strength of the brew. Hence longer brew times, or hotter brew water give darker cremas because they both increase the number of solubles in the cup and hence make the liquid darker (though it is very hard to tell the difference between a 20 second shot and a 30 second shot just by looking at the liquid, unless you dilute it or put a drop of it on some paper, or look under a microscope or.... etc).

I also find that the darker roasts give a particularly pleasing coloured crema, nice for latte art if you've no real plan on drinking it! (Unless you really like dark roasted coffee).

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another_jim
Team HB

#7: Post by another_jim »

King Seven wrote: Crema is merely a foam of the coffee underneath so the colour of the crema is entirely dependent on the strength of the brew. Hence longer brew times, or hotter brew water give darker cremas because they both increase the number of solubles in the cup and hence make the liquid darker (though it is very hard to tell the difference between a 20 second shot and a 30 second shot just by looking at the liquid, unless you dilute it or put a drop of it on some paper, or look under a microscope or.... etc).
Interesting, are you saying that crema is basically translucent, and merely lightens the underlying coffee color so one can see the differences in brew strength? It makes sense in a way, since super-lungos always seem to have an almost white crema.

In any case, I wasn't hypothesizing, just repeating conventional diagnostics and personal observation.
Jim Schulman

King Seven

#8: Post by King Seven »

I am. After all crema is CO2 trapped in the coffee liquid by a melanoidin present and fails due to drainage of the liquid so it would make sense. Plus I have seen a strong correlation between brew strength and crema colour.

Tiger mottling is still an interesting one, though I suspect that is down to small particles of roasted coffee suspended in the foam. Except the way it forms sometimes is a bit odd. Should probably get the microscope and camera out!

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another_jim
Team HB

#9: Post by another_jim »

King Seven wrote:Tiger mottling is still an interesting one, though I suspect that is down to small particles of roasted coffee suspended in the foam. Except the way it forms sometimes is a bit odd. Should probably get the microscope and camera out!
I've been thinking about it. I'm not sure it's a sign of quality. A slow start/fast finish pour will tend to be dark at the edges and light in the center. This cannot be a brew strength mechanism, since that only applies to the overall color. As the flow gets more even, one gets tiger striping, if the flow is very even, uniform crema.

Since it's unlikely that slow flow will dislodge more solids or oil droplets (which could also appear black due to prism like optical effects), it may be the fines that get through the basket's screen. These would appear early in the shot. If the flow is slow at that point, they don't mix, and get pushed in an orderly fashion to the edge. If the flow is faster, there's some mixing and tiger flecks. Fast flow gives complete mixing and no visible flecks (although they could be there, broken up into smaller patches, visible with a loupe)
Jim Schulman

King Seven

#10: Post by King Seven »

That makes a lot of sense. Often the flecks seem to be dragged from the edges and stretched over the surface during the second half of the shot.

Still want to take some microscopic pictures. I'd point the scope straight onto the crema if it wasn't going to steam up the lens! :)