I'm rather new to espresso making and I just got hold of a Gaggia Baby Class. I've noticed that, during extraction, if the color starts to turn to blonde early, I can stop the pump, and start it again the color will turn back to black and I can get some more extraction out of it before it turns blonde again. Why does this happen ? Is it recommended practice?

Hello Can what you describe isn't typically practiced to make espresso. Rather if your flow turns blond too soon it probably signifies that your coffee is stale (espresso is usually best with beans less than 14 days or so old from the roast date) or perhaps your grind size is too coarse.

You don't mention what you're using for coffee. Is it fresh? Are you getting about 2-ounces of espresso in about 30 seconds?

I would guess that your espresso machine has a pressurized portafilter and that cycling the pump essentially remixes the coffee grounds. It may produce a better looking espresso, but I doubt it is a better tasting one. If you're curious, try it both ways and let us know.

Fresh coffee + good grinder + standard (unpressurized) portafilter + reasonable brew temperature = good espresso. Change one of these important variables => lower likelihood of a good espresso.

The coffee I think was roasted around 2 months ago but the airtight package was opened just 2 days ago. The portafilter doesn't look like the one in the link (with only one hole), the filter basked has many holes in the bottom.

I don't know if it necessarily produces more, but kind of allows me to get more volume.. Unfortunately I haven't been able to consistently get good results yet, could be due to my grinder (Dualit = Solis 166/ Starbucks Barista). However I've gotten decent results a few times. There's so many variables that it feels really hard to get good results consistently!

namelessone wrote:The coffee I think was roasted around 2 months ago but the airtight package was opened just 2 days ago.

An airtight bag slows the staling process, but does not stop it. Deep freezing will slow it to a crawl (read Coffee: To Freeze or Not to Freeze for considerable detail on the subject). Roasted two weeks ago would be acceptable, but two months ago? Sorry, it will be very challenging to dial in that coffee since the grind setting moves finer and finer as a coffee ages, and the espressos will typically taste flat and bitter.

I will keep that in mind, and get hold of some new beans. One thing I've also noticed that it's very important that the portafilter is hot when brewing. Otherwise the result seems to be very sour and underextracted and tastes horrible.

Yes, make sure the portafilter is in the machine when warming up.

A cold portafilter will act as a big heat sink pulling heat out of the group and lowering the brew temperature. I use to think to myself 'ya it cools the group but it can't be that dramatic'. Then I mounted a thermocouple in the grouphead of a machine, pulled the portafilter, gave it a cold water rinse to bring it down to near room temperature and locked it back in. Almost immediately the group temperature started to plummet and did not stop until it was many degrees cooler. It took quit a while for it to rebound as well. So yes, your observation is correct, keep the portafilter in the machine. Low brew temperature leads to sour shots.

I would recommend against starting and stopping your machine, nothing good will come from it. When your shot goes blond, the coffee has given all it has to give; the rest of the extraction dissolves the undesirable soluble solids in the coffee giving you a bitter astringent cup. That is provided your grind/dose/distribution is good. As Dan points out, your coffee is well beyond its prime. Once that issue is remedies you can start working on getting the proper grind/dose for your machine.

Ah, thanks for the advice. Another question, when I use a single basket, one of the spouts seems to produce the desired caramel color, while the other is looking just blonde. Is that a sign of bad distribution, or just some side effects of old coffee?

Both could be to blame, but channeling is the more likely significant contributor. Diagnosing the cause of bad pours using old coffee is difficult and arguably pointless.

Just a comment about the original question- as far as I know, all of the Gaggia 'Baby' models have a 3-way valve that is activated (opened) when the pump turns off... so that means that all the pressure is released when you stop the pump.

Regards, Henry

cannonfodder wrote:A cold portafilter will act as a big heat sink pulling heat out of the group and lowering the brew temperature.

Hence the amazing and revolutionary "Portafreezo Technique."

Just to update this thread.. Finally I gave in and bought a Minimoka M203, and some new coffee.. Johan & Nyström Isola, Roasted a few weeks ago but packed (was the freshest I could find in that store). Anyway, after a bit struggling with the Minimoka , and finding out the manual was backwards with respect to which way you need to turn to grind, I managed to get a very good cup of espresso! Never knew coffee could taste a lot like chocolate. All that investment seems to be finally paying off.