Mystery blend 5 (bag #1) is as others have said, a classic comfort food blend. A medium roast, low acidity blend with lots of cacao and nut with a little light smattering of fruit. The blend is clean and free from any defects. While the primary flavor profile is chocolate and nut, I was getting just a hint of strawberry or kiwi fruit when the coffee was young. That faded as the blend aged. The blend has a mild sweetness to help balance out the cup. I thought it was an enjoyable espresso.

In milk, the blend held up well. I was adding just a dash of sugar to my milk to help balance out the bakers chocolate. There was no detectable fruit in a cappuccino, but the chocolate notes dominated the cup. As a traditional cappuccino, the blend held up well but I would not go above 5 ounces of milk. Beyond that the coffee gets washed out.

Blend 1 was easy to work with and had a wide temperature range and dose. I was getting acceptable shots ranging from 199 to 201 degrees. In the end I found the sweet spot to be 200.5 degrees with a 17 gram dose for 24 grams of extracted coffee in 27 seconds. Keep in mind that my espresso machine is a rotary pump so the system comes to pressure in 2 seconds. If you are using a vibratory pump E61 machine you may want to add another 3 to 4 seconds to that extraction time.

I would guess that the blend is heavy in Central American coffees with maybe a little Kenyan for the fruit notes. It did not have that signature peaty Sumatra flavor, but there is something there adding more bottom end than just a Brazilian coffee, maybe a Sulawesi? If you want a good solid coffee, this would be a good candidate. If you, or your friends, don't care for fruity, acidic, berry, citrus, etc... coffee and simply want a coffee that tastes like, well, coffee, this would do nicely. I enjoyed it.

Because of I've manage the distribution of the "mystery coffee" this year, I was usually aware, unlike the reviewers, of what coffee was being reviewed. This time around, the roaster suggested tossing in a wildcard espresso blend outside of their regular offerings; we dubbed these blends 5A and 5B, though none of us, including me, knew which was the regular offering and which was the wildcard.

Given that 5A is clearly a sweet chocolate and nuts blend with a large forgiveness favor, my bet is it's the commercial offering destined as a bar's regular blend. My early taste notes included light cocoa, walnuts, and a gentle tobacco finish. As other reviewers commented, this 5A is a near zero acidity blend. It's sure to be a favorite for those who love sweet chocolate traditional cappuccinos reminiscent of Ovaltine with a light dash of cinnamon. Those new to straight espresso drinking will appreciate its low acidity and non-aggressive profile; it performs consistently and predictably at most reasonable temperatures. I narrowed in on 200°F, dose of 17 grams, brew ratio around 60%. As it aged, I increased the brew ratio, leading to a sharper finish more like Baker's chocolate, nicely complementing small milk drinks.

In terms of dialing in, the second blend, dubbed 5B, was elusive. Visually the extractions were less even with clear evidence of spritzes, something that's rare enough nowadays that I'd considered them almost a novelty. Taste-wise, its chocolates were sharper and the finish had a slight bitter edge that might prompt some to add a half-teaspoon of sugar. I wondered about the "curve ball" the roaster claimed one of the blends would present: What could explain the fussier dialing-in stage? A melange coffee blend with hard/soft beans? Aged coffee? Some coffee component that's known for low fines production? I'm not sure and look forward to the reveal once the last of the reviewers have weighed in.

Mystery Blend 5A

Initial Preferences
Temperature: high
Dose: 16g
Output: 29g
Ratio: 55%
Time: 25s

A bright, shiny bag of beans sat on the countertop before me, beckoning further exploration. I approached the bag with a pair of kitchen shears and took an inch off the top. Hazelnut and dark chocolate are the dominant aromas. The break presents a rich, sweet aroma of roasted hazelnuts. It stands up well in the cup and offers a richer, more robust profile than the acidic single origins I've been drinking over the last month.

After a couple of gushers, the blend showed well as an upper-end shot. Higher temp, dose and ratio at a coarser grind setting than I'd expect. Raisins and turbinado sugar were at the front of the cup, with hazelnuts in the lingering finish.


Exploration
Time to turn on the jets. This is the first lower ratio shot that I've enjoyed in a long time, but that can't stop us from peeking around the corner. A tighter grind brought out some more focused sweetness. 16g in, 22g out. Not entirely surprising but nice to have in the corner. Going even further up the ratio ladder evened out the sweetness with hazelnut. This blend is exceptionally tolerant of grind and dose, so what about temperature? Dropping the temperature muted some of the flavors, but not to the point of unacceptable dullness.

Leverage
The chocolate-covered raisins made pulling shots a treat, but there wasn't much of a twist to the dose or other attempts at finding surprises. Swinging through high and low doses were pleasantly predictable.

Temperature: Medium
Preinfusion: 10s
Dose: 15.5g
Output: 26g
Ratio: 60%
Time: 26s

And in this corner...
With this blend, there isn't any real way to go wrong. Easy to work with on both the HX and lever, the chocolate, raisin and hazelnut trio didn't offer any surprises but kept a strong presence over a week's worth of testing.

Conclusions
If I still had a prosumer e61, it's be a match made in heaven. There are no dark corners or hidden mysteries. Milk drinks soften the hazelnut and keep the blend above water. Anyone looking for high acid had better turn elsewhere. There's nothing but easy chairs, fuzzy slippers and the evening paper in this blend.

Tony Dreyfuss of Metropolis Coffee Company sent me an e-mail revealing the Favorite Espresso Blend 5A and 5B as Redline and the custom-blended "Yellowline". See the introductory post for more details. Thanks Metropolis and reviewers for your writeups. The thread is now open for comments/questions.