Sour taste is likely under-extracted due to temperature being too low. Post a pic of your beans. I've seen but not tried LavAzza, but I've not seen that blend in particular before...

Assuming it's a less dark roast than what you've been trying, try switching to steam heat and running some steam through the wand after prepping your basket and then switch back to brew, do a short flush (just enough so you're getting water, not steam, you want it HOT) and pull the shot. You should be able to tame the sour acidity with more heat. If it goes bitter, flush a little longer and note how long (in seconds) between switching back to brew and pulling the shot. When you get it right, you'll want to know how to duplicate your efforts.

Cheers!

- Jake

Lavazza on the right,,, Carraro on the left:



Lavazza:



Carraro:

For the brew temperature:

First of all, i believe that farting noise is steam mixed with water,, correct me guys here!!!

The machine is set to height temp.

The machine was just started from a cold status, takes about 40 seconds to be ready.

What i did in sequence:

1- after ready, started the pump, you can hear that fart noise then goes away.

2- i started the pump again immedietly, no fart noise.

3- i engage the steam heat for five led flashes, started the pump, obviously the steam came back for a longer period then goes away.

4- if i increase the steam heat time, the pump will not start indicating a high brew temp according to the machine programming.

That being said, i have a digital thermometer, the max temp i could read is 86C, but i just insert the prop in the water and it might be very inaccurate, i dont know..

Thoughts????

Kemo_88 wrote:For the brew temperature:

First of all, i believe that farting noise is steam mixed with water,, correct me guys here!!!

The machine is set to height temp.

The machine was just started from a cold status, takes about 40 seconds to be ready.

What i did in sequence:

1- after ready, started the pump, you can hear that fart noise then goes away.

2- i started the pump again immedietly, no fart noise.

3- i engage the steam heat for five led flashes, started the pump, obviously the steam came back for a longer period then goes away.

4- if i increase the steam heat time, the pump will not start indicating a high brew temp according to the machine programming.

That being said, i have a digital thermometer, the max temp i could read is 86C, but i just insert the prop in the water and it might be very inaccurate, i dont know..

Thoughts????

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Ok. Couple things.

1-Your beans look plenty dark still, but not charred or anything like that. They shouldnt taste sour if your machine is up to temp.

2-40s is nowhere near long enough for you machine to be up to temp. I know it's telling you that it is, but it just isn't.

How long can you leave it on before it times out? I would leave it on, with the portafilter in it for at least a half hour, if you can. For any thermal stability with a machine, you need the entirety of the brew path to be as close to brew temp as possible. In 40s, your portafilter, shower screen, brew valve, etc... will still be room temp. You want the portafilter to be close to dangerously hot before you dose into it. By the time you lock it back in, it should still be uncomfortable to touch any metal parts on it. You could also shorten the warm up time by soaking the portafilter in boiling water, but a hot portafilter is a good indication that the rest of the group is hot enough to brew, as well.

As for measuring the water temp, you'll want to cut a Styrofoam cup down so the top rim is the same diameter as your portafilter. Jam it up into the group with your thermometer stabbed in through the side and run the pump. The cup will keep most of the heat from the brew water in it and give the thermometer a chance to read accurately.

Also remember that the best shot to drink straight will not make the best milk drink and the best shot for a milk drink will not test the best straight. But both should be drinkable straight and taste pretty ok in milk drinks.

Good work!

- Jake

Thanks Jake for your advice..

I always ran an empty shot through the portafilter to heat it up, some times twice.

The machine has three setting for auto off, currently it is on 9 min, but i believe it can be set to "never".

I once opened the top cover, the thermoblock is far away from the group head and shower screen, they are connected by flexiable tube, so the more i leave it to heat up, actually the group head and shower screen will get cooler with time, the thermoblock is not on the top of the head.
Am i right?, any way will try leave it for a while.

Jake_G wrote:
Also remember that the best shot to drink straight will not make the best milk drink and the best shot for a milk drink will not test the best straight. But both should be drinkable straight and taste pretty ok in milk drinks.

- Jake

Actually, i believe that is true., i read people describe espresso taste from high qualty cafes as a lemon squeezed in to it, and that is it should be...

Kemo_88 wrote:Thanks Jake for your advice..

I always ran an empty shot through the portafilter to heat it up, some times twice.

The machine has three setting for auto off, currently it is on 9 min, but i believe it can be set to "never".

I once opened the top cover, the thermoblock is far away from the group head and shower screen, they are connected by flexiable tube, so the more i leave it to heat up, actually the group head and shower screen will get cooler with time, the thermoblock is not on the top of the head.
Am i right?, any way will try leave it for a while.

You are experiencing the reasons why many of us on HB have moved away from thermoblock machines. They can be coaxed into delivering a tasty shot, but it is tough...
I would experiment more with what you've been trying, maybe purge some steam through the portafilter, with it locked in the group. The difficult thing is maintaining temperature throughout the shot. Water gives off its heat willingly to cool objects, so getting everything as close as possible to brew temp before starting the shot will allow more of the brewing process to happen at target temp.

It can be done. Slightly better equipment will do it with slightly less effort on your end. Much better equipment will do it with slightly less effort than slightly better equipment.

Cheers!

- Jake

Kemo_88 wrote:i read people describe espresso taste from high qualty cafes as a lemon squeezed in to it, and that is it should be...

...only if you like lemon in your coffee. Most of us don't. Espresso "as it should be" encompasses a broad spectrum of tastes - but "there's only one best taste - the one I prefer". We've followed you through your long struggle to get great espresso from a machine that may fall a little short of the mark. You're doing very well (based on your descriptions), but at some point you'll have to accept the best you can do with it or move on to a better machine. Although you can have a lot of fun with a VW GTI, you can't win Formula 1 races with it and it won't pull a horse trailer. Stuff is what it is and you generally get what you pay for.

Jake_G wrote:Sour taste is likely under-extracted due to temperature being too low.

Ok, from my little experience, under-extracted can be from a coarse grind too, fast flow, stopping the shot early (resstrito)

Actually i never thought that different beans can have different characteristics.

No matter i keep grinding coarse to get a 30 sec shot, i cant,, the flow is always slow even with just pressing lightly with the tamper.

My previous attempt, i was stopping the shot at 27-30 sec because i didnt want to over extract it, but maybe i was under extract it instead by trying to fulfill the rule of 25-30 sec, may be it need more water and extract a little bitterness to balance the taste..

Today i set the machine to high temp, before it was medium, engage the steam heat for seconds then purge for two seconds, made sure the basket is hot enough,, and pulled the shot, actually guys, the flow is a little orange in color, like some lemon juice is comming out with the coffee,, i will film it next time, but i am sure it was orange , not brown.



I let the machine complete the shot, it took about 40-42 sec, and for a slow flow, i think the yield falls in the range of 40-45 grams,, and this time i added sugar to the milk,, i think the taste was balanced with some acidity you can feel at the back of the mouth, maybe it is the coffee, because the acidity rate on the bag is 2/5, so i must expect some acidity there.

What i don not understand is why crema is very thin, not like the previous coffee that has a ton of bitter crema, this one is supposed to be 100% arabica, from what i know arabica beans has more crema than robusta...

Actually, I think that in general, robusta is known for more crema. And it can, depending on roast and bean, have a stronger/harsher taste to some people.

I use two roasts primarily: one is a medium dark local roast, no robusta. Balanced and terrific both as espresso and drip. I also use Josuma Malabar Gold, which does include some robusta: much much more crema, great as espresso and milk drinks, but a sharper tastes. And it does not taste good at all (to me) when drip brewed.

So your results comparing a blend with robusta and one with 100% arabica seem correct to me.