Help! Great espresso yesterday, today it's bitter. Why?

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#1: Post by Shuka »

Please help me! I've been cappuccino-ing for about 7 years... variety of machines... one cap a day... now I'm on a QM Andrea Premium with Eric's thermometer and a Eureka Soecialty 75. I'm using a mix of spring and filtered water. I buy 5 lbs of coffee and freeze small ball jars with about a weeks worth of beans each. Usually 4-5 days post roast before freezing. Light wdt, leveler, light tamp. Bottomless IMS with very little headroom (18g basket).

So my problem: I've been using Nossa Familia Camila beans lately, a medium-dark roast that I haven't loved... until yesterday. I had just gotten back from a week and a half work trip, and left beans in the hopper for my wife (a mocha-lover who doesn't care about the coffee). 20.5 gram dose... 201° (best I can tell)... 25 grams out... fantastic! Good enough that I think it could have been served at Blue Bottle- intense flavor, mellow, caramel, malt. Dee-licious in my book. I just want that again! (And again..)

But today... nothing like yesterday. More bitter, none of that "forward flavor). Unfortunately... this was the last 30 grams of my last 5lb purchase, so I can't keep testing with "known beans".

So what changed? I thought- maybe the resting of the coffee? But a one-day change? Doesn't seem likely. So what am I missing, and how do I get that flavor consistently?

Thanks- I'm desperate!
Good morning, Sunshine!


#2: Post by FlutterVeiss »

Well of course there could be any number of things about routine that were slightly different that could affect it, but it sounds like you have a fairly regular routine so, tabling that, I do actually have a thought.

I usually let my coffee rest for at least 7 days off-roast before I pull any shots with it at the earliest. Now I'm usually on the lighter side so it takes a bit longer to off-gas, but I wonder if that particular coffee was benefiting from the "extra day" of off-gassing. I know freezers are really good at keeping coffee fresh but I'm not sure exactly how much of an impact it would have. What I will say is that CO2 has a bitter taste, so could be as simple as that.

The other thing that interests me is you say you're tamping lightly? The other thought that occurs to me is if you happened to tamp a bit harder that day it could have resulted in more resistance and higher contact time with the puck. Do you happen to remember if the shot took longer than usual to pull?

You've been at it longer than I have so this is just what strikes me reading your post, no offense meant if this is all really obvious to you!

Shuka (original poster)

#3: Post by Shuka (original poster) »

Hi - thanks for the thoughts! You help me realize that perhaps I've been too blasé in pick prep. The Eureka makes such nice grinds, that I often just tap to flatten, then use the leveler and tamp. Things generally look fine on the bottomless, but....

For tamping, I'm also not very intentionally consistent...

So two ways to "buckle down". Will do.

But! 1) shot speed is pretty consistent... and the butter day was after the golden day. Do you think a day extra of aging could add bitterness after a week and a half?

Good morning, Sunshine!


#4: Post by FlutterVeiss »

I think I misunderstood a bit from the first time - I thought you were saying the really good day was one that was left out slightly longer and then the bitter was from frozen. So I don't think aging would be the culprit here, if I had to guess.

As far as tamping goes, I usually press down until I feel a bit of resistance (i.e. I've compressed until the air is gone). I think the best way to experiment is to have a system that's as consistent as possible so that you can change one thing at a time. Really drastic bitterness vs. non-bitterness I'm assuming would be from a major change. So if the puck prep, grind setting, or water temp was dramatically different. There are some fairly inexpensive (for this hobby) ways to help be consistent with things like getting a calibrated/self leveling tamp (they have a rim on top to align the tamp with the portafilter and a spring that keeps the tamp force consistent every time).

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#5: Post by iploya »

Shuka wrote:20.5 gram dose...201°... 25 grams out...fantastic!..But today... nothing like yesterday. More bitter...this was the last 30 grams
I find mysteries like this irresistible, even though I'm not necessarily very good at solving them. Usually there is something conspicuously absent in the fact pattern that begs to be probed.

First, you say the good day was 20.5 grams in, 25 grams out at 201F. So that's the recipe you'd try to replicate.

But then you refer to "the last 30 grams" on the following (bad) day. Is 30g the dose you used? Or did you just grind 20.5g of the remaining 30 and then repeat the winning recipe? Did you track the shot time each day and was that fairly constant?

Incidentally, a darker roast can taste very good at the ratio you describe (around 1:1). It can be sweet and syrupy. I'm just not clear from the post if and how carefully you are repeating the parameters from shot to shot, day to day.

Shuka (original poster)

#6: Post by Shuka (original poster) »

Hey you two-

I woke up this morning (I'm still lying in bed), thinking about the beautiful grinds from the specialty 75. And thought of an explanation that connects to what you bring up, Iploya.

The great shot was ground directly into the portafilter, and was the second grind of the morning (I usually don't bother purging the grinder each morning). But the bad shot (because I was concerned that there was not enough beans) was ground into a small pitcher for weighing, and was the first grinds of the day. Pouring the grinds from the little pitcher into the portafilter makes a relatively clumpy and uneven puck.... I didn't notice a significant change in flow rate, but I don't measure it every time, either.
(There was still enough coffee for my wife's single.... Hence the 30 g).

So perhaps relatively poor (but not terrible!) puck prep and a few grams of day-old funds are enough?

Feeling better...and committing to either purge or make my wife a mocha first thing from here on out.
Good morning, Sunshine!