gilrain wrote:I understand that concept, and no doubt will eventually employ some compromise... but, in general, I don't subscribe to the "do what's most enjoyable" school of thought, when it comes to culinary issues. I would be without many of my now-much-loved pleasures, following that rule... wine, tea, scotch, and suchlike.
Hallelujah!
As far as espresso temperature goes, it works similarly to brewed coffee. This means its effect will actually be more familiar to people who cup, where both the hot and cooling cup are rated, than people who just drink espresso, where the custom is to drink it as soon as possible.
The hotter the coffee, the more the mouthfeel and roasty flavors are accentuated. As the cup cools to room temperature, the fruity and acidic flavors will come to the fore, the bitter flavors will change from roasty caramels to more astringent tannins, and the mouthfeel will become much lighter.
In general, espresso is so concentrated that: 1) the flavors need to be buffered by the crema, and 2) the acidic and tannic flavors are overwhelming unless balanced by caramels and sugars. This is why the custom is to drink it hot and fast.
However, this is changing just a little. A lot of work is going into blends that use more expensive and more acidic beans by balancing them with coffees that are almost excessively sweet. Blends like this can benefit from a 30 second wait or a cooler cup.