Ive been working on this for awhile now, and---after two failures---I finally get to report a success, at least a modest one.
My first coffee extract was made in similar fashion to my tobacco cooks. I ground up 30grams of roasted Sidamo Guji beans (a delicious specialty bean from Africa that I home-roasted, as I do all my coffee) at espresso grind (very fine), added 200mls of 75% PG and 25% VG, did a two-day heat process of four low-heat cooks that consisted of six hours at simmer followed by six hours rest, then used my three-stage filtering process. That produced 150mls of coffee extract. Results in DIY juice were not dreadful, but decidedly odd and unsatisfying. The coffee flavor was sort of hollow, with a slightly metallic side-taste. I have no idea where that metallic taste came from.
I altered the process for my second attempt. I used 30 grams Central American home-roasted beans instead of African, and I ground them much coarser---a French-press grind rather than espresso grind. For the liquid, I again used 200mls, but this time it was 50% VG and 50% water. I speculated that the absorption of flavinoids from the coffee might be better with water.
Then I did a short-heat, long cold-steep method. I microwaved the slurry for 15 seconds four times over four minutes to kick-start the extraction, then I put the maceration in the refrigerator to cold-steep for a week. Then I filtered the liquid in my now-standard three-step fashion. The results were awful. So bad, in fact, that I poured the entire batch of extract down the drain.
One thought that Scarfy brought up recently is that instant coffee might work better. Instant coffee is natural, which is to say, its made from real coffee beans, and some brands use no additives. I did some research online to see what brands of freeze-dried instant coffee were most favored by reviewers and consumers.
Today I purchased a small bottle of Medalia dOro Instant Espresso Coffee thats imported from Italy, which had received good reviews as a reasonable facsimile of real espresso. Some reviews considered it a bit in-your-face with its strong potency, but the consensus was positive. It was the only highly-rated instant coffee available at my local Fred Meyer here in Florence (I had wanted Bustello or Pilon), so I bought the Medalia D'Oro. The two-ounce bottle was $4.79.
Upon opening the bottle at home, I discovered that this coffee is different from the freeze-dried crystals of many other brands, which are chunky, sharp little bits, almost like tiny rocks, while the Medalia DOro is fine and granular---not powdery at all, but composed of uniform grains about half the size of sand. I dont know the manufacturing process used by Medalia D'Oro to get from coffee to grains, but I have to admit that I trust the Europeans somewhat more than I do any of the big American grocery store companies to make their product in a way that's natural and non-toxic.
I took a 50ml glass bottle of my Sidamo Guji extract and added 1 1/2 teaspoons of the Medalia DOro granular coffee. After shaking the bottle for quite awhile, the grains of instant coffee still hadnt dissolved in the 50/50 PG/VG extract liquid. So, I microwaved it in four short bursts of ten seconds each over five minutes and then let it rest for an hour to cool. That seemed to work to dissolve the grains of instant coffee into the liquid, or so it appeared visually.
Next, I mixed up a 5ml bottle of DIY Sidamo DOro Espresso using 15% extract at 24mg nic in an overall base of 25/75 PG/VG. Since I was still concerned with particulates, I loaded the juice into a new 3.0 ohm Boge SR510 carto, thinking that if the coils were going to get gunked up, the filler material would delay it. I vaped the carto on a VAMO set to 7.5 watts RMS.
Wonder of wonders, its actually pretty good! The hollowness and metallic taste of the Sidamo Guji extract are gone, replaced by a sharp and pungent espresso flavor. Not sweet at all, but not sour, either. I vaped the carto for 20 minutes, then topped it up by adding one drop of liquid stevia and eight drops of FA Cream Fresh DIY juice.
Voilà! Cappuccino rather than straight espresso. Its still potent and sharp, but the cream and a tiny bit of sweetener have smoothed it out nicely. Wow. Its not just vapeable, its really good. More like real espresso than regular coffee, but thats fine with me. Mixed at a lower percentage (say, 8-10% extract), Sidamo DOro should made a lovely base for Starbucks-type drinks, like Vanilla Frappuccino or Caramel Macchiato.
My next experiment will be to make another batch the same way, but to forego the Sidamo Guji extract as a base and instead use pure, unflavored PG/VG with the Medalia DOro. That should be interesting.
