Grinding coffee for moka pot
I recently bought a Bialetti 4 cup stainless moka pot and a Baratza Virtuoso and my first attempt at making my own grounds came out badly. I have some Illy to compare so I got my grinder to produce grounds that felt and looked similar in size. The grounds did clump a little bit when I got it to what looked like a similar grind size compared to the Illy grounds.
I put the grounds in the basket, about 3-4 table spoons and leveled it off with my finger. I the pot on the stove and the resulting product was thin, unlike what I got with the Illy grounds, and horribly bitter. The body was closer to what I get out of my Melitta style pour over than espresso.
When I went to clean my pot, I noticed that the grounds in the basket only filled about 2/3 of the basket which was completely unexpected. Normally I get a tightly packed puck all the way to the top of the basket when I use the Illy coffee grounds.
It sounds like a couple of things to me:
1) too finely ground (bitterness)
2) not enough grounds in the basket (thin body & low grounds volume)
It also sounds like the new coffee is either oilier or has higher moisture content (the clumping), which may keep you from getting as much coffee into the basket as you think you're getting. I spoon in enough to light pack down with the back of the spoon & get it level with the top of the basket. If the Illy is drier, then it'll settle more on its own without you having to anything extra.
Pre-ground is almost always drier, in my experience, but I've only ever had a can of Illy one time. I do know that the Illy screw-on top is less gas-tight than a simple snap-on plastic lid. Many Illy roasts are lighter than their North American counterparts (assuming you're in North America).
Yes, home-ground should be "fluffier" than vacuum-packed. It might also have more of a static charge, leading to less-dense bulk.
Try a slightly more coarse grind & pack it in a little.
I found the instructions in this piece very helpful in getting really good coffee out of the Moka pot. You'll see that a couple refer to excess bitterness coming from too fine grounds or leaving the heat on too long. Also very important is to start with cold water and make the coffee over low heat.
Perhaps this will help? http://www.sweetmarias.com/brewinstr/...
I own 3 stainless moka pots, 2, 4 and 6. I used to use them regularly but honestly haven't done so in a long while but they look GREAT on my shelf :-). I would not recommend tamping, at least not to start. I also agree that a coarser grind is probably the correct approach. Also please do start with cold water and be careful to not use too high a flame. If I do recall correctly (questionable), the "lowest flame that still gets the job done" is a good approach. High temps will scorch the coffee and a bitter result.
I hope this helps!