Gassy crema dissipates quickly

Beginner and pro baristas share tips and tricks.
Deebo

Postby Deebo » Mar 11, 2018, 4:02 pm

So I've been making espresso at home for a few years now, and about a year ago I upgraded to the prosumer level. I can make awesome shots, but there is something I've been dealing with for awhile that I am taking on again in an attempt to solve. I have researched this issue extensively and not really been able to find any true insight. The issue is that the crema I produce is extremely gassy and tends to dissipate quickly. It doesn't seem to change no matter how old the beans are (3 days post-roast all the way out to a month). If I pull a shot in a volume glass and stop it at 60 ml, the crema will dissipate and leave me with something like 30 oz, weight about 20 g in the cup (from a 20 g dose). If i tried to pull it out to weight 40 or 50 grams in the volume glass, it would overflow with crema.

I am at altitude (Denver), but I visit shops here all the time that pull perfect looking shots. I do freeze my beans, but I have the same issue whether I do or not.

It's funny, if I pull a long black by eye it tastes amazing, but if I get out the volume glass and scale and really try to get everything exact is where I'm having all the issues. Also, blend doesn't seem to be an issue as I change frequently.

Set up:
Rocket Mozzafiato type V
Baratza Sette 270

Thanks.

foreseeablebananas

Postby foreseeablebananas » Mar 11, 2018, 9:53 pm

20g in and 40g out is a pretty standard ratio in specialty coffee these days. Why does crema matter if your shots taste all right? Just something to think about.

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Jake_G

Postby Jake_G » Mar 12, 2018, 12:31 am

I should preface this with the full disclosure that I have no experience pulling shots at elevation, but from what I've read, I suspect the shops in Denver have lowered their brew temperature so that the crema can hang around long enough to look good and have tailored their roasts to taste best at that temperature. You can try this but depending on the bean you will then have to play with grind, dose, and likely extraction pressure to try to get your flavor back. Your best bet is to make sure you're brewing a bean that prefers a cooler brew temperature and go from there. An Eric's group thermometer will really help you out if you don't already have one because at your elevation, your flushes would need to end a few seconds before the water dance ends, which is a tricky thing to estimate...

This post by Jim Schulman contains some very useful info for folks in your situation.

Cheers!

- Jake

daveR1

Postby daveR1 » Mar 12, 2018, 1:23 am

I've seen similar issues with some coffees. I'm at 4300' here in Salt Lake City and much of the coffee I order comes from at or near sea level. Generally, I found that if I let the beans rest longer (sometimes as much as 2 weeks past roast), the crema improves.

Deebo

Postby Deebo » Mar 12, 2018, 12:06 pm

foreseeablebananas wrote:20g in and 40g out is a pretty standard ratio in specialty coffee these days. Why does crema matter if your shots taste all right? Just something to think about.


Well, mainly its just an issue I've decided to revisit, I rarely pull by volume. I think to sum up my main concern though, if I stop the shot at 60 ml, and it settles down to 30-40 ml, how much of a shot did I really pull? I guess I'm confused on that point.

daveR1 wrote:I've seen similar issues with some coffees. I'm at 4300' here in Salt Lake City and much of the coffee I order comes from at or near sea level. Generally, I found that if I let the beans rest longer (sometimes as much as 2 weeks past roast), the crema improves.


Interesting, and so you're even higher than me and getting the same results huh?

Jake_G wrote:I should preface this with the full disclosure that I have no experience pulling shots at elevation, but from what I've read, I suspect the shops in Denver have lowered their brew temperature so that the crema can hang around long enough to look good and have tailored their roasts to taste best at that temperature. You can try this but depending on the bean you will then have to play with grind, dose, and likely extraction pressure to try to get your flavor back. Your best bet is to make sure you're brewing a bean that prefers a cooler brew temperature and go from there. An Eric's group thermometer will really help you out if you don't already have one because at your elevation, your flushes would need to end a few seconds before the water dance ends, which is a tricky thing to estimate...

This post by Jim Schulman contains some very useful info for folks in your situation.

Cheers!

- Jake


This is interesting, in short, this could be a temperature issue? I generally flush for 2-3 seconds after the "dance"... the recommendation would be to shorten this? I really hate the aesthetic of eric's thermometer, which is why I never got one, but I wonder if the cheaper one would help me figure out a better flushing routine.

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Radio.YYZ

Postby Radio.YYZ » Mar 12, 2018, 12:21 pm

Deebo wrote:Well, mainly its just an issue I've decided to revisit, I rarely pull by volume. I think to sum up my main concern though, if I stop the shot at 60 ml, and it settles down to 30-40 ml, how much of a shot did I really pull? I guess I'm confused on that point.

...



Try weighing the 60ml shot and see what you get, weight will always be the definitive answer to the yield of your shot.
Good Coffee: Technique/Knowledge > Grinder > Beans > Water > Machine

EvergreenBuzzBuzz

Postby EvergreenBuzzBuzz » Mar 12, 2018, 2:05 pm

Devin, I am up in Evergreen and don't seem to have an issue with my dual boiler machine, S1. So your comment on your flush could be relevant.
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daveR1

Postby daveR1 » Mar 12, 2018, 5:56 pm

Devin,
Aren't you in Denver, isn't that @ 5300' higher than Salt Lake?
One of my favorite spots is a coffee shop on the mountain @ Alta ski resort @ 9000'. I'll have to ask them if they've had similar issues.

BTW - it only happens with some coffees. I got some coffee from Caffe Umbria in Seattle the other day & at 6 days post roast, the crema had a lot of large bubbles. @ 10 days post, the large bubbles have decreased and the flavors improved. crema is still a bit thin compared to some other coffees.

FYI - I base all my recipes on weight, using volume as only a very general indicator.

EvergreenBuzzBuzz

Postby EvergreenBuzzBuzz » Mar 12, 2018, 6:26 pm

daveR1 wrote:Devin,
Aren't you in Denver, isn't that @ 5300' higher than Salt Lake?
One of my favorite spots is a coffee shop on the mountain @ Alta ski resort @ 9000'. I'll have to ask them if they've had similar issues.


Does it matter that its an HX machine? I am not an engineer type. I don't get this at 7750 feet on a dual boiler?
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homeburrero
Team HB

Postby homeburrero » Mar 12, 2018, 6:53 pm

Deebo wrote:This is interesting, in short, this could be a temperature issue? I generally flush for 2-3 seconds after the "dance"... the recommendation would be to shorten this? I really hate the aesthetic of eric's thermometer, which is why I never got one, but I wonder if the cheaper one would help me figure out a better flushing routine.


I'm at 5000 ft here in Albuquerque, and have found that I need to stop very soon after the end of the water dance. If I were to stop according to total flush volume, or by grouphead thermometer reading , the altitude wouldn't make much difference, but the end of the water dance of course would be expected to happen later and at a cooler temp. I generally stop the cooling flush right about the time I hear it subside on my Giotto Evo for a flush-and-go. Try some shorter flushes to see if the taste improves, but don't expect that to reduce your bubbles.

I had the same reservation about the appearance of the EricS grouphead thermometer but got over that and am glad I did. For flush-and-go from an idle machine I could work fine without it, but for subsequent shots, for learning about the machine, and for knowing right away when I have a stalled thermosyphon it has proved indispensable.

There seems to be general consensus that giving roasts a long rest is a good idea at altitude - ask at the shops there in Denver that you like - they may be resting their beans longer than you do. Here's a topic with some good posts about that: Espresso at altitude - Could use some theory . Also see this post - About Roasting and Brewing at Altitude from an experienced home roaster and barista (Martin) who moved from New York to Santa Fe. Note that he had the bubbles, but found it best to ignore them.
Pat
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