After making good progress on my previous thread I have made a number of observations and would appreciate some comments.

According to the very useful espresso guide on this site I was expecting my extractions to run from sour to sweet and finally to bitter. However I think all of my extractions start incredibly bitter (I can taste the bitterness for a long time after) followed by a period of less bitter (but not sweet by any means) and finally the flow becomes watery.

I have to date produced 1 properly sweet shot and a few ok shots but the majority are still savagely bitter.

I have replicated this with various good coffees (friendly espresso blends mainly).

In addition I have recently noticed the crema is often horrific with an almost powdery texture to it.

Any thoughts/advice?


Thanks,

The first drips can be incredibly bitter; you can start the shot and let the first drip fall into the tray, then put the cup under the portafilter (tip - that causes a little mess on the bottom of the cup; you can just catch the drips in something else, like another cup or a saucer, with the target cup in place to catch the rest of the shot).

This technique is useful if all else fails.

I used to hate when someone would write that it is the Mano variable that needs work but keep the faith because your shots will get better!

A few tips; make sure that you can produce consistent shots. That means if you use 16gm of grinds to produce 32gm of liquid, you should be able to do that 8 out of 10 pulls (within reasonable tolerance). Until you can do that, you are really chasing a moving target. Also, rent a Scace device and check your temps. Bitter shots usually means too hot.

I found that until I worked out all the problems that interfered with my consistency, my shots were hit and miss. Now that I've finally worked out my equipment and technique, my shots are about 75-80% good. It was a long road that's still winding ahead but at least now, I enjoy most of what I produce.

Channeling will get you a thin, bitter, watery (no body) shot. A high temperature will also get you a bitter shot no matter what you do. The Rocky will benefit from a WDT to aid with channeling. Beyond that, temperature control could be one of the many culprits along with dose accuracy which requires a scale.

I'm hesitant about weighing in, being fairly new to all this myself, but I note from your earlier thread that you're using Hasbean coffee with a gaggia - and I had precisely the same issues at first with this combination. The taste you're describing is almost certainly the result of underextraction. His coffees are uniformly delicious, but generally very bright and tricky to extract on a gaggia, and the underextracted=sour/overextracted=bitter thing just doesn't work for them. It's almost impossible to get an overextracted bitterness in my experience - they just go a bit dull. To extract them properly I've found that you need either high temperatures or slow extractions (but never both at the same time). I think you also need to restrict yourself to about 25g of liquid in the cup, 30g at the very most, as the temperature of the water hitting the puck is plummeting by then. I see you're in London, might I suggest that you get yourself along to St Ali on Clerkenwell road to try some of their Cult of Done blend and buy a bag or two to take home to play with? This is a much easier coffee to brew - chocolate and nuts with a pleasing acidity. A breakthrough moment for me came when I had a very tasty espresso there and later that day recreated the same drink at home. Whilst you're in that part of town, you might pop into Prufrock, just around the corner on Leather Lane, to taste just how good the brighter style of espresso can be. Good luck!

One other question. How old is, or rather how many pounds have been ground through your Rocky's current set of burrs? I've found the shots deteriate substantially after 75 to 100lb max.

Since starting on this forum I have always weighed the doses using a 0.1g scale and wdt as well.

Rocky has done <5kg so I don't think that's the problem.

GlennV wrote:I'm hesitant about weighing in, being fairly new to all this myself, but I note from your earlier thread that you're using Hasbean coffee with a gaggia - and I had precisely the same issues at first with this combination. The taste you're describing is almost certainly the result of underextraction. His coffees are uniformly delicious, but generally very bright and tricky to extract on a gaggia, and the underextracted=sour/overextracted=bitter thing just doesn't work for them. It's almost impossible to get an overextracted bitterness in my experience - they just go a bit dull. To extract them properly I've found that you need either high temperatures or slow extractions (but never both at the same time). I think you also need to restrict yourself to about 25g of liquid in the cup, 30g at the very most, as the temperature of the water hitting the puck is plummeting by then. I see you're in London, might I suggest that you get yourself along to St Ali on Clerkenwell road to try some of their Cult of Done blend and buy a bag or two to take home to play with? This is a much easier coffee to brew - chocolate and nuts with a pleasing acidity. A breakthrough moment for me came when I had a very tasty espresso there and later that day recreated the same drink at home. Whilst you're in that part of town, you might pop into Prufrock, just around the corner on Leather Lane, to taste just how good the brighter style of espresso can be. Good luck!

Interesting and sounds similar to my findings. In my case the initial liquid is highly offensive and the blond final liquid never seems to go bitter, just progressively weaker. I will try measuring the temp throughout the shot when I get a chance.

Have updated my location, never even noticed that!

In my case the initial liquid is highly offensive and the blond final liquid never seems to go bitter, just progressively weaker.

Actually, as it should be. Or at least that's how those brew phases should respectively taste. I'd like to see you stop the extraction a little earlier and see if that doesn't help a bit. It's not going to make a massive improvement.

Let's nail down a few things while you wait for the temperature measurement device.

How long does one of your extractions take? Is time a function of grind and appearance? Or are you brewing to a pre-determined time whatever the stream looks like?

Nice that you have a scale. What's your current dose? What's your brew ratio? Why did you choose that particular brew ratio.

How are you measuring (even if by guess) brew temperature now? What do you do to control temperature?

Many of the problems you describe can result from the presence of rancid oils in the brew path.

How clean is your espresso machine? How often do you backflush? After backflushing, how clean is the water in your blank basket?

How often do you wash your basket and pf? Do you wash disassemble and wash them separately? What does the pf look like after it's been washed?

How often do you use a commercial espresso machine cleaner. How often do you soak the basket and pf in cleaner? How often do you remove your pressure screen and showerhead, and soak them in cleaner?

BDL

I am aiming for 25-30s for 45-60ml of liquid.

I have tried dosing 14 or 16g but always seem to settle back on 16g. The last time I measured the brew ratio it was 55% but it might fluctuate a little.

I am measuring temps using a multimeter and thermocouple which I have calibrated against boiling and iced water. My gaggia fluctuates its brew temps a fair bit due to small boiler so I try to start brewing 30-60s after the boiler switches off which based on previous measurements I took seems most consistent.

I have cleaned all the bits I can get to (portafilter, basket, shower screen), but because my machine doesnt have a 3-way valve I dont think I can backflush. Portafilter is bottomless and I soak it in dishwasher soap approx weekly along with the shower screen. It looks very clean to me. I descaled last weekend.

Never used commercial cleaner in the machine for the reason stated above.