Sour Shots

In trouble shooting La Peppina, (actually is is more truthful to say, "in trouble shooting my own techniques" (because I don't think it is the machine at this point) I took some pretty accurate measurements of the water coming out of the group compared to the water in the boiler (measured from the bottom aluminum plate). I removed the screw in the front of the machine (there is an o-ring) and put some foil in the PF that allowed some water to go through and some came out the hole. Used a Thermapen thermometer which is fast and accurate enough. I can confirm that the machine is very stable and that the water coming out is consistently approx 3 degrees cooler than the water in the boiler.

Regarding the sourness, I'm still puzzled, but I think it must be the coffee. As an experiment (actually, I admit it was an accident), when roasting I over cooled the beans with mist. That batch was incredibly sour as in biting a lemon! Other batches vary in the sourness to drinkable to the undrinkable.

The Blue Bottle Retrofit I bought on Thursday also was a tiny bit sour, but not as bad as mine. I thought my taste buds were going, but I confirmed the above with a third party. I'm also getting sour shots on the Gaggia Classic. So, I think that pretty much confirms that my coffee is to blame. Though, I don't recall this problem at all 3 weeks ago. I'm going to try roasting some preblended SM espressos later today.

Its interesting to line up shots, taste them hot and then let them cool to room temp and taste again. At room temp I found I could really identify the differences much more easily than at hot temps. I put them on a sheet of paper and make notes etc so I don't get them mixed up. Perhaps the coffees I'm using are not suitable for SO espressos and either need to be blended or used otherwise. I'm relatively new to roasting but I have roasted about 200 batches (using hot air gun) and have never ruined a batch except the three batches I did where I for some unknown reason (or in the interest of science) decided to over spray them. I'm going to stop spraying and use a fan to cool going forward.

In terms of shot color, consistency and crema, I am getting very good results with the Peppina. I'm going to update my naked portafiter thread as well.

dan

DJR wrote:I can confirm that the machine is very stable and that the water coming out is consistently approx 3 degrees cooler than the water in the boiler.

Small note: tastewise, the brewing temperature is one degree (1C) lower then water temperature in the boiler. I have it confirmed with two different coffees. But: I don't own a scace and I base my brew temp vs. boiler setting offset guessing on Vivaldi on measurement done by Niko on his machine and video-posted on s1cafe forum; and I have the heavier portafilter on my La Peppina.

Sounds like your making progress. As for the O-ring on that screw on the front of the group, I must be missing that. I don't know the temp delta, but inferred from others that it was a few degrees. I'm thinking of poking my digital thermometer through a small cork and seeing if I can get a read on it.

It still fascinates me that there's a steel La Peppina portafilter out there, it would be interesting to find out how that came about and it does look like it has the same geometry as the other aluminum ones but is clearly much heavier.

I need to roast up more coffee and espresso, down to just some old (19 days post-roast) Brazil Vargem Grande as I used up the last of the IMV today. Playing with the Chemex has me going through my coffee much quicker now, it's great for making more then two cups of coffee and should work as a replacement for an automatic drip machine, but the temptation to drink two cups instead of one in the morning is too much for me these days. Must roast more.

Chris, I'm astonished with the difference too, and I'm going to ask the lady from whom I got the machine about it. She quite has them many.
On a similar note, have a look here. La Peppina Termomatica.

Picture from the auction on ebay. There are some more, and a nice close-ups too. I bet it's a surprise for everyone.

Curiosity got the better of me today so I wrapped some yellow electrical tape around the stem of my digital thermometer and stuck it in the front of the group. I had to hold it with my thumb while pulling to keep it centered so it wouldn't touch the metal and also prevent spraying myself with water, I put a paper towel in the double basket to add some resistance to be able to measure the water temp.



The peak temp I measured (which I wasn't able to capture with the camera as I had one hand on the thermometer and portafilter and one hand on the lever) was just one degree (F) below the temp on the PID (in a re-purposed case). I figured it would be closer to two or three degrees, but it was pretty close. This still doesn't give me the temp of the water hitting the puck, though, as I'm measuring above the dispersion screen, but at least it's consistent with what your seeing. I did find the O-ring inside the hole, I guess I was expecting to see it on the threads of the bolt, so no worries there.

As for the Termomatica, there've been a few mentions of this one on HB, François posts some pictures of his beautiful model here and Roeland posts an exploded parts diagram from Ebay here.

After I got done playing and made some burritos for the family dinner tonight, I pulled a nice double of Brazil Vargem Grande that's getting pretty long in the tooth (nineteen days rest) that gave me a very nice, chocolatey shot. The grind was a little tight so I had to help with the lever and ended up with a ristretto.

Temp

I found that when measuring the temp at the boiler, it is quite a bit hotter, the lower one goes. 3 degrees F or so between towards the top and the bottom.

I measure at the plate above the heating elements. It could be even hotter below the heating elements.

I don't usually get involved in the discussion of shot quality etc, as this is a very subjective concept and many times involves more variables than can be taken into account, some of which are left out inadvertently while the observer fixates on this or that point....but as you know there truly is lot to sort out and when the frustration point has bee reached it gets even harder to make sense of any issue. I can't summarize all of the La Peppina use and misuse methods posted here but to note that they all differ from the original instructions, which is a good thing. But the La Peppina has always seemed the most straight forward of machines in usage. Kettle brought to full boil. Turn off. Pull warming shot through pf. Dry pf and dose 5mm from rim. Lock in pf. Pull down handle. Slowly guide handle up until it feels resistance against the puck. Return handle to bottom and release. Of course there are all kinds of variations on the last part which is the fun thing about the La Peppina.....one can be as minimalist or hyper ritualistic about it and the shots are generally in a very good range, from good to great with the occasional OOPS!

But as an aside, I can relate one experience that taught me an object lesson. Dialing in a Faema Velox.....sour shot after sour shot with each sour shot leading to an increase of the thermostat and the shots just kept getting more and more sour. I was mentally insistent that logically increasing the temp would eventually lead me out of the sourness. I ran this by my spiritual espresso adviser and he mentioned that I may have been mistaking bitter and sour and he was right.....the shots were too hot and I indeed do have trouble differentiating bitter and sour as this is for some a learned skill. Dialing back the temp did the trick, especially for the beans I was using at the time.

Thanks, Doug. Very helpful and keeps things in perspective. The one I got from you is very nice. What i need to work on is my roasting and blending skills.

Wow, Chris, thank you for the measurements!
I usually do 2 or 3 preheat pulls, then I take the basket out and put pf back, then with coffee back to pf and pull. I noticed, that contrary to Caravel, the temperature readout on my thermometer drops somewhere between the last flush and before I'm back with the coffee in the basket, so before I lock back in I turn the heating for a moment on. On Caravel I do flush the group too and seems like there's no offset, that's why I'm doing without thermometer immensed in the kettle (I'm mostly drinking coffees that like ome 91 to 93C temps) - just have a higher temp water for flush and then it drops to accurate for brewing just on time.

Funny thing with the Termomatica... I saw the diagram but didn't look closely, and of course visited the gallery already too, yet didn't remember!

Daniel, my laboratory thermometer is long one and I naturaly measure temperature at the bottom plate of the jug (and still it sticks out high ); thanks for the note, for I was going to buy a shorter 'tea thermometer' as they call it in a shop, but then I would only be able to measure at the middle, and that probably would be less acurate.

Doug, it's nice you chimed in
Straithforward as it is, La Peppina offers huge flexibility too, and rewards very well time spent with her. Preinfusion is the sole thing that can make all difference in the shot taste, and I can say it just after one and a half week of (regular) use! Two preinfusion moves amplifies body, heavier notes, some low bittery and deep flavors; five yields light cup, still standing its legs on earth yet looking up high in the sky where light shines out from the blue from behind light white cloud; and four give outstandingly balanced shots, with all the taste notes laid out straight and distinct, in a manner of perfection.
It's one truly capable machine of deep-diving into taste of coffees and modeling shot taste.

La Peppina Cup Wamer

I noticed an off-hand reference in one version of the manual that recommended the top as a cup warmer. I tried it for the first time today and it's probably the hottest cup warmer in the business. The ridges on the black plastic top keep the cup from forming a seal and the steam is directed right to the cup bottom. It heats it up very quickly and it isn't warm-- it's very hot. It's a nice feature that seems under utilized. Very clever design and eliminates the need to preheat cups with water.

dan