Ideal crema is dark, light, or golden?

[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.

[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.

[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:)

[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).

[psyclus]

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

[King Seven]

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).

[another_jim]

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.

[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!

[another_jim]

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)

[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!

[psyclus]

UPDATE: To keep the discussion flow together, I've merged this thread with your previous one. If it turns out to be a bad idea, I'll split them later. Thanks, Dan



i just got a used Gaggia classic, but my espresso is far from even looking like, or tasting properly..
i just learned that hot water equals dark crema, and colder water equals cream or lighter colored crema. I checked water temp using a milk-thermometer and what i got was 65 degrees celcius... What's the deal? did i just buy some crap or what??
im a poor student, thats why the economy buying..

help please

[King Seven]

Your milk thermometer is unlikely to be very accurate.

Some questions - what coffee are you using? how fresh is it? What is your shot time and for what shot volume? How long are you leaving the machine to warm up before using it?

[krus]

When brew temp is held constant throughout the shot with less than 1 degree variation, that is when you'll notice the redder crema develop. This is thought to be the sign of a really good extraction. Some machines aren't capable of this degree of stability. Most measurements I've taken on smaller heat exchange machines show a variation of 2-4 degrees from the start of the shot to the end. Even with commercial machines, it's not always possible to achieve this degree of stability due to several factors. It sure is beautiful to look at.

[cannonfodder]

Given some practice, you can get there.


Well, that is actually from my two group, but this is from my modified Isomac. I added a HX preheat loop.

[King Seven]

When brew temp is held constant throughout the shot with less than 1 degree variation, that is when you'll notice the redder crema develop. This is thought to be the sign of a really good extraction. Some machines aren't capable of this degree of stability. Most measurements I've taken on smaller heat exchange machines show a variation of 2-4 degrees from the start of the shot to the end. Even with commercial machines, it's not always possible to achieve this degree of stability due to several factors. It sure is beautiful to look at.

I just don't see the science behind this claim - that somehow a stable temperature changes the colour of the coffee liquid to a more reddish hue. I've heard it many times, and obviously read it in Schomer's writings.

In truth I could make no claims for the stability of this machine (I just haven't tested it) but is this red enough for you?

[cannonfodder]

I wonder how much a plane ticket to London is.

[cannonfodder]

In retrospect, I find that the color of the crema is influenced more by the blend contents than machine temperature. For a sure fire brick red crema pull some SO shots with Yemen.

[HB]

I just don't see the science behind this claim - that somehow a stable temperature changes the colour of the coffee liquid to a more reddish hue.

I can readily agree that delivering stable ("flat line") temperatures increases reproducibility, which increases the likelihood of an exceptional espresso simply by eliminating a source of variance. But I remain unconvinced that one temperature profile is superior to another, not only because of the lack of empirical evidence, but it doesn't even make intuitive sense. Consider the measurements below:


Cimbali Junior - puck top and bottom temperatures (more)

The temperature gradient from top-to-bottom doesn't close until the final moments of the extraction. Evidently the different coffee layers are subjected to a range of temperatures throughout the extraction; it's our hope that this concert of extraction temperatures delivers the desired flavor profile.

Allow me to digress...

I wonder, if one measured the temperature mid-puck between the flattest flat temperature profile and the humpiest humped profile, would the plotted differences be obvious? Are we in reality dealing with such small differences that crude measurements are red herrings? I'm reminded of the news story about the chimp genome project. Perhaps the answer to unlocking godshots is the same as the answer to the separation / similarity of chimp and man - just a few minuscule but critical differences.

Let's take a look at the temperature profile of the Elektra Semicasa Automatica:



Jim commented in his writeup:

However, the Semiautomatica's espresso prowess presented a problem while researching this review. By the standards of most US espresso experts and by my experience with espresso machines, the Elektra should make mediocre shots, not glorious ones. The car versus motorcycle analogy applies--in trying to explain why the shots are great, I feel like a four wheel car expert trying to explain just how a two wheel motorcycle can stay balanced. There's a very basic principle of espresso extraction I'm just not getting.

This confirmed something that I've suspected for a long time: The more I learn, the less I know.

[King Seven]

I think repeatability is always the key with brew temp. I still don't know enough about profiles to stake myself to flat line or any other style of brewing. But as long as the kit does it time and again then that is just one less headache when you are chasing a shot around, trying to capture the taste you are after.

Roast colour has a massive amount to do with the colour of the pour, as of course does temp and flow rate. I just can't accept blindly that flat line temps change the colour of the brewed coffee above and beyond any other extraction.

[maze400]

I thought the crema was influenced more by tamp pressure or grams of coffee used?