Why no crema?

#1: Post by **LittleCoffee** » July 31st, 2023, 4:55 am

I'm trying my hand out at medium roasts which I've never done before. I'm used to dark roasts and lots of crema (Sumatra Mandheling is my daily driver), and I think I can just about extract what is a balanced shot skill wise.

I'm extracting these beans https://www.redber.co.uk/collections/al ... dium-roast on day 3-4 post roast. I think I'm getting a balanced shot at 2:1 ratio. But the espresso is basically like an americano crema wise - there is a tiny bit but it's a world apart from what I'm used to in dark roast land.

Is this a medium roast thing? Or are some beans just like that? I would have thought freshly roasted medium beans ought to have a lot more CO2 in them than a dark roast so am surprised am getting this.

Thanks in advance for any thoughts.

#2: Post by **Jeff** » July 31st, 2023, 8:11 am

Little crema is very common with medium and lighter roasts.

Depending on how lightly roasted (the link is 404) "filter" roasts might be better at 1-2 weeks off roast or more.

#3: Post by **JohnB.** » July 31st, 2023, 8:52 am

Light roasts might not produce much crema but I get normal amounts with the medium (Full City) roast coffees I use regularly.

July 31st, 2023, 9:16 am

Thanks Jeff - have fixed the link - I clipped the last character off in the copy paste.

I'm surprised lighter roasts can have little crema - I thought crema was the CO2 content of the bean coming out during extraction. Shouldn't medium and lighter roasts leave more CO2 in the bean vs. dark and if so then how do they end up with less crema? And for the avoidance I've doubt - I'm doing espresso only.

#5: Post by **yakster** » July 31st, 2023, 7:13 pm

Crema relies on emulsified oils from the coffee in addition to the CO2, the lighter roasted coffee won't be as oily.

#6: Post by **espressoren** » July 31st, 2023, 8:24 pm

I think CO2 in beans is largely a byproduct of the roasting itself, rather than inherently in the bean and getting roasted out like caffeine. There is probably a peak though at some point.

#7: Post by **langonej** » August 6th, 2023, 4:48 pm

Too fast of an extraction (too coarse of a grind)?

#8: Post by **bullet08** » August 7th, 2023, 12:24 am

Arabica has less crema than robusta to begin with.

#9: Post by **cannonfodder** » August 7th, 2023, 11:47 am

Crema varies blend to blend and origen to origen. Many things impact the volume of crema. Do not use crema volume as your sole coffee quality yardstick.

I would expect to get no less than 1/4 total by volume of crema from any coffee based solely on the beans in the blend. If you are getting less than that, then you may have an age issue or quality of bean/roast issue. While it is an indicator of freshness and quality, it is not the only measure.

#10: Post by **Ken5** » August 8th, 2023, 3:36 am

cannonfodder wrote:I would expect to get no less than 1/4 total by volume of crema from any coffee based solely on the beans in the blend. If you are getting less than that, then you may have an age issue or quality of bean/roast issue. While it is an indicator of freshness and quality, it is not the only measure.

Curious, when do you measure the volume of crema? If I use a shot glass to make a shot almost all of the shot is crema for the first half of the shot. After that the volume goes down quickly. After the shot rests for about a minute the side of the cup has a little less than a 1/4, but the center of the shot has just a very thin film which I see when the spoon goes in to stir.