Hello, in recent years I invest very much in coffee and I read about it a lot but all these years I was involved only with filter coffees (V60 and Aeropress primarily), and last few days I decide to dive into espresso and see what I can do. So I buy a very Moded Gaggia Classic with an Ascaso isteel i1. I try a lot of coffees and a lot of adjustments but my shot is always very acid (or bitter, I can't decide) in the aftertaste. For example, if I take a big sip when I swallow the coffee the acidity (or bitterness) kind of burns my throat.

Here is every Infos I can provide to you about the shots.

I use 21gr of coffee and a 2:1 ratio

-The coffee I use is this https://imgur.com/a/vunLjdW


-The first drops appear at 5 to 6 seconds and the brew stops at around 28 secs

-My shot looks like this https://imgur.com/a/hukpCiE


-And my puck like this https://imgur.com/a/d18Klxn


-My temp is set at 93C.

-I use double filtered water and my machine is always as clean as possible

So this is everything I can provide to you. My question is do I do something wrong and my shots taste like this or this is what should taste (Again I was primarily a filter coffee nerd).

Thank you for your time!

First resource is Espresso 101: How to Adjust Dose and Grind Setting by Taste

21 g sounds like a lot to me. I'd guess that, with a standard basket, 18 g or less. The "nickel test" to see if you're likely overfilling the basket uses a coin about 2 mm thick. If it leaves an impression in the dry, tamped puck when you lock it in, you are probably overfilling. You can go under a bit, but going over often leads to problems.

What does your shot weigh? It looks like it is "short". With a medium or medium-dark roast, roughly 1:2 by weight is a good place to start to get close. 18 g grinds : 36 g espresso, for example.

Past "that looks good", you'll have to rely on your taste. Uneven extraction, as well as some other cases, can be both sour and bitter at the same time.

bilisios wrote: if I take a big sip when I swallow the coffee the acidity (or bitterness) kind of burns my throat. !

I don't know of any taste buds in our throats, I wonder if the previous owner who did the mods also acid cleaned the machine before selling it and possibly didn't flush it adequately. If you have a ph test kit I would check the water coming out of your machine.

Hello:

Welcome to HB. 8^)

bilisios wrote: ... shot is always very acid ...

Please do take a look at these links:

search.php?keywords=espresso+bitter&ter ... t=0&ch=300
and
search.php?keywords=espresso+sour&terms ... t=0&ch=300

As you can see there are a great many entries but that only reflects the incredible breadth of the data stored in posts at HB.
But fear not, you can narrow the search by searching again within those same results.

You can also try searching with the 'Enhanced by Google' option at the top.

/search-res ... resso+sour

/search-res ... sso+bitter

Best,

CIV

Is you coffee fresh, as in it has a roast date and is within the last fee weeks or month? I find it much more simple to obtain a sweeter shot with fresh coffee. The freshness contains more oils and holds the pressure back of the espresso machine more evenly extracting the flavors.

I find when coffee is older it is much more subject to channeling and finicky. The extractions are quicker and I find that the result is typically bitter.

August 23rd date on the bag, so, if anything, a bit too fresh if a light roast.