Espresso temperatures

[pszilard]

In my quest to get on well with Miss Silvia, I would like to determine what is the "good" espresso water temperature.

Using a dial type drink thermometer (the type used for milk frothing measurements), I measured the water coming out from Slivie after she has been on for about an hour or more, both from the Portafilter and from the frothing wand - but not in steam mode. In both cases I extracted a full cup volume, to minimise temperature losses due to warming the cup itself. I also held the tip of the thermometer away from the wall of the cup, to get a true measurement of the central part of the hot water.

In both cases my thermometer showed about 72 deg C, which I thought was too low, hence this post.

So;

Question 1: What temperature do others get? Please specify machine and temperature, when expressing water without coffee, and then with coffee (short black, of course).

Question 2: What is the "recommended" ideal temperature? I thought that the water hitting the coffee grind is meant to be 92 deg C, which should be therefore what comes out when there is no coffee loaded or from the wand. Even allowing for some cooling, I would have thought that 72 was too low.

Question 3: Can the solenoid pressure be adjusted on Miss Silvia? I am suspicious, that mine has too high a pressure, resulting in the water passing through the coffee grinds too quickly ( and not hot enough), and giving poor quality of extraction.

Thanks for your input...

[Fresh_Coffee]

Re: Espresso temperatures

Hello Paul,

just quickly and not precicely as you requested:

"Well priced" dial type thermometers are often "out" so I dont really use them for this purpose. I use a reasonable quality digital thermometer. I push a foam takeaway cup up into the group ring area, poke a hole just above the bottom and just big enough to get the thermometer probe into the cup, and push it in.

Activate the group and read the temperature at whatever part of the pour you wish to measure but remember you only need to pour out very little say no more than 60 ml. (Theoretically 30ml for the brew and another 30 mll to account for water that would have remained in the puk)Aim to read somewhere around 90 to 92 degrees C. but the spec is around 88 to 93 degrees depending on whose "bible" you read. Loss in temp is quick so dont just stick the thermometer in a cup on the drip tray, and dont use a cup that will absorb heat from the water.

We generally expect a reading in the mid to low seventies for the actual brewed espresso temperature in the cup, the temp loss is great, this would be considered normal and is why everything should be prewarmed. Temperature loss is your enemy.

The group solenoid is not an adjustable item, it is no more than an electric tap that simply opens or shuts off the flow of water when electrically energised.

You are probably referring to pump pressure and whilst many will tell you to adjust or modify so you can adjust the pump pressure, I have never seen a silvia that I couldnt brew a decent espresso out of as set by the factory. Yes it may be improved, but what I am getting at is that it is unlikely that any standard factury setting will result in your machine not working properly except if it has actually "broken down" in some way.

Flow and pressure are not necessarily related and adjusting pressure up or down will not I think increase or reduce flow. The flow from your machine is governed by the designed set up of the pump, and the backpressure to that resulting from the fineness of grind supplied, the size of the dose supplied, and the pressure of the tamp supplied (by you, in the filter).

Looking specifically at the last sentence of question 3, I would be concerned that you may be barking up the wrong tree in chasing machine problems that may not be present. It is very possible this may be due to operator technque. Do you live near any coffesnobs or anyone for that matter, that could quickly check your machine (not with instruments) and simply advise whether it is working properly and doing what it should?

Hope this helps.

Regardz,
FC.

[JavaB]

Re: Espresso temperatures

In my quest to get on well with Miss Silvia, I would like to determine what is the "good" espresso water temperature.

Using a dial type drink thermometer (the type used for milk frothing measurements), I measured the water coming out from Slivie after she has been on for about an hour or more, both from the Portafilter and from the frothing wand - but not in steam mode. In both cases I extracted a full cup volume, to minimise temperature losses due to warming the cup itself. I also held the tip of the thermometer away from the wall of the cup, to get a true measurement of the central part of the hot water.

In both cases my thermometer showed about 72 deg C, which I thought was too low, hence this post.

Hi pszilard....

Those type of thermometers just wont "cut it" when it comes to measuring anything other than the temp of a large volume of milk/ water...

Because of the large mass of metal, they "steal" too much heat from the liquid under test and give a low reading (they also have to be immersed quite deeply in the liquid..... and you should not be measuring any greater volume than 60ml. (cold water replaces the hot in the boiler and reduced the temp).

You need to beg, borrow or buy a multimeter with a thermocouple probe.... these have a small bead at the end which you can place into the pf - through the spout - or you can also use a foam cup - but only "extract" 60ml for your measurement.

Question 1: What temperature do others get? Please specify machine and temperature, when expressing water without coffee, and then with coffee (short black, of course).

You will need to get the correct type of measuring device to get valid comparisons.

Question 2: What is the "recommended" ideal temperature? I thought that the water hitting the coffee grind is meant to be 92 deg C, which should be therefore what comes out when there is no coffee loaded or from the wand. Even allowing for some cooling, I would have thought that 72 was too low.

The temp should be about 92-93 deg C ... although some like to brew as low as 88 deg C.... Id recommend 92-93.

Question 3: Can the solenoid pressure be adjusted on Miss Silvia? I am suspicious, that mine has too high a pressure, resulting in the water passing through the coffee grinds too quickly ( and not hot enough), and giving poor quality of extraction.

There is no pressure regulator in the current model Silvias (the latest model will have one). Most do use a bit too much pressure (10.5 to 11 bar compared to the recommended 8-9) but this does not cause a problem if you are using the correct volume of grounds, at the correct level of fineness and with the correct tamp.

But get yourself the correct measuring instrument before getting too concerned!

(beaten.... and what FC said above!)

[pszilard]

Re: Espresso temperatures

Doing a Google, has turned up the following:

From http://www.coffeeresearch.org/espresso/potential.htm

Water temperature - The water temperature should be stable and somewhere between 92-96°C. The choice of the espresso machine is very important to both water temperature and temperature stability.

http://www.lucidcafe.com/cafeforum/factors.html states 203 deg F which equals 95 deg C.

And finally here is another informative link: http://www.sweetmarias.com/prod.rancilio.shtml

ps: I just weighed mySilvia PF handle without a coffee basket and it was 575g.

[pszilard]

Re: Espresso temperatures

I did have a 1hr lesson at Di Bartolis which is where I bought the Silvia. I know Renzo is happy for me to go back for another run and even take my own Silvia for comparison to his demo unit.

I will also go to Jaycar and look for a thermocouple digitherm.

And thanks for the quick replies too. All responses are absorbed into the gray matter

Cheers,

[Fresh_Coffee]

Re: Espresso temperatures

Renzo is a good bloke & will help you, just take the machine back in and all will be well.

I would however advise against rushing out to buy any form of instrument to measure anything with on the machine. Its pointless.

The machine needs to work well as set by the factory. Good and understanding operator technque is a given.

Heres a hypothetical. If after taking your readings they dont match with what you expect or what you have read or been told, but the machine is set as per the factory and the vendor advises it works just as it should, then what to do?  Rancilio and their importers, agents and vendors are not going to go modifying a factory set machine particularly if it can be demonstrated to do what it should be doing irrespective of what you have measured.

The moral of the story is....dont read too much into all this tech stuff that gets thrown around on websites. Talk to Renzo.

Regardz,
FC.

[robusto]

Re: Espresso temperatures

Renzo, I can understand your need to know. Its natural when so many figures are flung around, and you feel as though youre working in the dark unless you know what your own machine is doing.

Dont go electrocuting yourself.... but when you get a digital multi-metre with thermocouple, first of all immerse the thermocouple into boiling water.

Take a reading to ensure it is 100 degrees (at sea level).
I wont even attempt to go into the ice bath calibrations --boiling water does it for me.

Satisfied your gadget is accurate, attach the thermocouple on top of the boiler, close to the thermostats up front. Once again, be careful -- there are deadly live wires all round.

If you brew when the temperatures on the boiler stabilises around 108 to 110 degrees, the temperature exiting the portafliter should be at the required 93-95.

Dont buy a digital thermometer -- its response time lags way behind whats happening in the boiler.

Use a good DMM or a PID.

--Robusto

[JavaB]

Re: Espresso temperatures

Renzo, I can understand your need to know. Its natural when so many figures are flung around, and you feel as though youre working in the dark unless you know what your own machine is doing.

Yep so do I.

Whether you are a "snob" (in the coffee world), a "geek" or a "nerd" you have to know what is going on and why. 8-)

Im a frequent contributor to Whirlpool as well (the "geek" Internet users site).... and it is the same there.... why do I have those figures in the modem?, why is my line so bad? how can I measure this or that?...

We must be a pain in the A to suppliers of goods and services because we ask why (or why not) and we want an answer...... we will complain if we dont get one (or if we see it as a "brush off")... we discuss what is happening and we try to improve things.... it is the nature of the beast which we are. And its people like us who often make things better for the consumers who dont care about such issues.

I say well done to the snobs, geeks and nerds of the world! (and sorry to the suppliers to whom we cause grief) - but we will make a difference!!

[Dimal]

Re: Espresso temperatures

Gday Paul,

Id go with FCs advice in the first instance, makes sense and he has been "in the game" a long time. Worry about all the other stuff after you have Silvia singing and dancing to your own tune , funny thing is, after you get to this stage theres a lot less reason to start playing around under the bonnet

Mal.

[telemaster]

Re: Espresso temperatures

The only thing i would add to the above is that when answering a similar question a while back, I replicated your test (which another reader had done) and found that the 70 something C from the milk therm was about 92 C from inside the filter basket using a thermocouple.
I agree that this is interesting but unnecessary.
The simplest thing I do on my botticelli (similar to silvia) is to let the element heat the boiler until the thermostat turns it off and then do a quick flush to get rid of boiling water before I put the handle in to brew. It does make for a sweeter extraction on my machine (there are people who would disagree with this process- it works for me on both my very different machines). It is much simpler than temperature surfing and getting paranoid about the process.

Im not sure if silvia gets this hot- FC or others would know.

Brett

[robusto]

Re: Espresso temperatures

Brett, not sure whether I read your post correctly. You leave the portalifter OFF until youre ready to brew? Is that correct?

--Robusto

[luca]

Re: Espresso temperatures

Question 2: What is the "recommended" ideal temperature?

I would however advise against rushing out to buy any form of instrument to measure anything with on the machine. Its pointless.

I could not agree more!

There is only one way to adjust temperature that makes any sense and that is something that I will reveal shortly ;P For now, I want to point out that temperature is only really worth concentrating on after you have the other variables under control. A good test of your barista skills is to get a bunch of 30mL shot glasses and a stopwatch and see if you can get five 30mL pours in a row that are all within a three or four second extraction time window.

As others have said, measuring espresso temperature is a lot more involved than simply using a dial thermometer. In addition to a lack of accuracy, Im surprised that no-one has mentioned that dial thermometers have quite a lag time due to the mass of the probe.

All temperature measuring devices will give you a degree of error. Even a relatively cheap multimeter with a K-type thermocouple will probably give you +/- 3% in error. That means that if you read something like 92C it could be anything from roughly 89C to 95C. Then theres the whole problem of measuring things consistently. Measuring what is coming out of the spout as opposed to measuring water in free flow without a portafilter, measuring with a bead probe on top of a tamped bed of coffee or measuring with a probe in the coffee will all give different results. Then you need to remember that the room temperature ground coffee will rise in temperature as hot water flows through it ... so you either need to pick a point in time to measure the temperature at or you need to actually plot it as a graph!!

All of this makes for a major headache when you are trying to compare brew temperatures across machines. Someone might well say "95C is the best brew temperature," but that is pretty much entirely meaningless unless they specify the method by which that temperature reading is obtained and the audience then uses the exact same piece of thermogadgetry to go and measure it in the same manner. In fact, in order to do the temperature testing on the machines trialled for the World Barista Competition, Greg Scace, a scientist from NIST, was enlisted and he came up with a specially designed thermofilter. Combined with an appropriate multimeter, the "Scace device" costs over $US500!

So all of this brings me to my point that slavishly extracting at a recommended temperature is not actually that likely to get you the result that you want in your cup. The only worthwhile way to adjust temperature is by taste. For example, if something tastes really sour, go to a higher temperature. If something tastes burnt and ashy, go to a lower temperature. I work on commercial machines that have adjustable temperature readouts that are calibrated at the factory, but it simply doesnt matter whether your machine has a digital temperature readout, a bar pressure gauge or whether you just wait X seconds after the heating element goes out. The principle is the same.

What temperature do others get?

When I had my Silvia, I got the best results when I waited between about a minute and a half and two minutes after the heating element light went off. I have brewed espresso between 88C and 97C according to the temperature readouts on the machines that I have used. There is certainly no generic temperature that will work with everything, but Id guess that most commercially available blends would probably like temperatures between 91 and 95C. On my home machine, 1.0 bar at the upper end tastes right for the blends that I have been using. Generally, lighter roasts will need higher brew temperatures and darker roasts will need lower brew temperatures, but this is not always the case.

To bring the discussion back to you, if one day you roasted something a bit too light, you might, for example, want to have a go at brewing it immediately after the element light goes off to see if it likes that hotter temperature a bit more.

Cheers,

Luca

[luca]

Re: Espresso temperatures

Quote:
Question 3: Can the solenoid pressure be adjusted on Miss Silvia? I am suspicious, that mine has too high a pressure, resulting in the water passing through the coffee grinds too quickly ( and not hot enough), and giving poor quality of extraction.


For the past few weeks, I have been experimenting with the brew pressure on my machine and I definitely think that a lower pressure makes ones life easier. Im sitting at about 8.5 bar at the moment.

The silvia, unfortunately, has neither a brew pressure gauge, nor an adjustable overpressure protection valve. This means that to tell what the brew pressure is, let alone to adjust it, you need to have access to a portafilter-mounted pressure gauge.

For years, some silvia owners have modified their machines. I never did this to my machine because it is a procedure that carries some potential risk and will definitely void your warranty. Horror stories that I have heard include unseating parts on the inside of the boiler, allowing water to drip back into the reservoir so that an air pocket develops in the boiler and, of course, electrocutions and breaking other random parts. Of course, some people have reported success, but, given the risks, I would advise steering clear of it.

Rancilio seems to have heeded the call that machines should work well ex-factory. The latest US silvias seem to have an adjustable OPV. If and when this model makes it to Australia, and it might have already for all I know, perhaps the part will be available to buy so that you can retrofit it.

Now, I have talked a lot about the minutii and I want to finish off this post by reiterating the old adage that the problem is usually on the handle side of the portafilter. By far the best investment that you can make is to buy some decent coffee and plough through it in a session working on your barista technique. In the first session, dont worry about temperature at all and dont drink any of the espresso. Just get some shot glasses and a stopwatch and work on consistency. For $15 in coffee and 45 minutes of your time, I think you will be very happy with the improvement. This was the very first thing that I did when I got my machine and I am very glad that I did so, as it enabled me to get decent shots in the first few days. I have attached a photo to prove that Im not kidding ;P On your second session, you can start tasting some coffees, but Id probably try to keep it to five or fewer shots in a session if you want to taste them because the group will probably heat up a bit. Of course, doing a training course will skip you ahead even faster, but you will get the most out of it if you do a session at home first.

Quote:
The simplest thing I do on my botticelli (similar to silvia) is to let the element heat the boiler until the thermostat turns it off and then do a quick flush to get rid of boiling water before I put the handle in to brew. ... Im not sure if silvia gets this hot- FC or others would know.


The silvia group is not directly on the bottom of the boiler as it is in your botticelli, so if they had the same tstat, Id expect the temp to be a little bit colder. However, a shot with a warmed silvia immediately after the light goes off would have tasted quite burnt to me, so maybe the tstats arent the same. Just idle speculation. But I find it difficult to understand how a flush that gets rid of boiling water would work ... I havent ripped open a botticelli or anything, but if the brew water comes from the bottom part of the boiler, as it does on the silvia, I would expect it to be the coolest water in the boiler ... so the rest of the shot would be too hot. Its not like a HX, where you flush out overheated water. But this is a lot of speculation - there could be a million other things like the effects of convection currents and pressurised systems ... frankly, I prefer just sticking to pressing the buttons in some way that gives good coffee ;P

Cheers,

Luca

[telemaster]

Re: Espresso temperatures

Brett, not sure whether I read your post correctly. You leave the portalifter OFF until youre ready to brew? Is that correct?

--Robusto

No dont leave handle out- just take it out to dose after I do a flush to get element heating, then flush boiling water then handle back in- very short process, but yes, the handle stays in the rest of the time the machine is on.
Brett

ps re Lucas comment about hx flush and botticelli- I agree theyre not the same but the botticelli does have boiling water (or close ) coming out of the group head after the thermostat turns the heater off and if you dont flush the coffee tastes burnt. Im not sure why this is because there isnt the E61 heating going on (not an E61 machine!). Im aware of what Sparky said about boiler currents.
Whatever is going on, with the flush, I get results close to the bezzera after a cooling flush. If it is just till the water stops sizzling I get a sweet unburnt espresso. If I flush much longer I get the nasty under temp bit (and heater goes on during extraction) With no flush you get burnt coffee.
An aside- this is my second bott- the first one (dropped on a concrete floor by a technician and replaced) didnt need the flush.

[Viviane]

Re: Espresso temperatures

Thanks for those posts, Luca, there is a lot of good information there.

Perhaps someone could get you a nice set of matching coffee cups for Xmas? ;D