RapidCoffee wrote:Just one more observation:
It should be obvious that espresso machines are not designed for one and only one dose, since they come with both single and double baskets. If the "proper" dose for singles is 7g, and 14g for doubles, then dramatic changes in dose are not only possible, but to be recommended. The "proper" dose depends, at least in part, on the size and shape of the filter baskets. I believe it also depends on the coffee, the grind, and the grouphead geometry.
This is undeniably true.
I would not apply words like "proper" (I realize it was in quotes above) to this discussion.
There are two major issues; those related to equipment and those related to taste.
As regards equipment, this is hugely variable and some equipment used in certain ways will be able to produce an acceptable looking shot over a very wide range of doses. We already know from an evaluation that Jim Schulman and I did (
http://www.home-barista.com/espre...e-redux-t1302.html) that even simple modifications changing the pump pressure profile can markedly reduce channeling. If one were to use a larger PF basket and a more sophisticated pressure ramp up, the sky could be the limit on how much coffee you can appear to extract for a given shot size.
You are going to extract different things from a given amount of coffee with different grind sizes and doses, through which a certain amount of water is run through at a certain pressure over a defined period of time. (how's that sentence for a mouthful?

)
The result is that the taste and the flavors and what I might call the "balance" of the beverage will be effected. To give a non-espresso example, I've had the opportunity to drink a couple of different interesting Chateauneuf-du-Pape (southern Rhone red wines) recently. One was a 1989 from a highly regarded and famous producer (Chateau Beaucastel) and it came out of a magnum sized bottle. The other was a 2003 from another good producer which came out of a regular sized bottle. 1989 was a classic and excellent vintage and 2003 was a bit bizarre as it was a produced during a summer noted for its abnormally high temperatures which resulted in an earlier harvest than usual.
The 1989 was among the finest red wines I have ever drunk, perfectly aged and with a very fine balance between the "fruit," the acidity, and the complexity. The 2003 in comparison, although also very good, was very ebullient, in your face, full of fruit, but without the complexity of the 1989. I'll hazard a guess that most experienced wine drinkers (maybe all) would vastly prefer the 1989 however among new wine drinkers the 2003 would probably have been the favorite. To me, although I enjoyed the 2003 (and have more bottles of it so I'll be drinking it in the future, like it or not), it lacked what I will call "balance," or "equilibrium." I'd probably rather drink the 2003 by itself or with some very strongly flavored food, whereas the 1989 needed to be consumed with a more sophisticated and subtly flavored dish to appreciate its charms. Far be it from me to try to tell anyone that they should love the 1989 and dislike the 2003; they are both good for certain people at certain times and circumstances which are not the same.
Getting back to espresso, in addition to the questions about whether or not (and how) a given setup of equipment will extract varying doses of coffee, there are the questions of taste and "balance" (here comes that word again!) Far be it from me to try to tell someone else what is necessary to get a "balanced" taste out of an espresso. This is all going to depend on a person's taste and how they consume the espresso. If you drink primarily milk drinks, the intensity (of say) a 20g double shot may be very much softened by the milk, and for a given person (and depending on how much cow juice they drink with the espresso) a 14g shot might taste "diluted" to them. So be it. Drink what you like.
For me, 14g of espresso in a double basket in my equipment produces a "balanced" beverage for me, whether as a straight shot or in the sort of cappas that I make which are probably on the low end of the volume scale. One thing is for sure; if you use a blend that is designed for use in larger than "standard" doses, it will effect the taste if you use it in smaller doses. My own experience is that "headliner" blends that are typically used in large doses taste rather bland in 14g doses, so I'd avoid them if your intention is to use "Italianish" type dosing.
Finally, getting back to something that I suggested a long time ago in another thread, when we approach newbie home barista types (who typically have simpler and unmodified equipment) we should probably suggest to them that they start out with a "foolproof" approach that will bring them success rapidly in their own espresso adventures. To me, that means suggesting the use of ~14 doses with minimal basket preparation. There will be ample time in the future for them to experiment with other approaches, but it would probably be best for them to get a handle on the process and experience some early success with it. Only if they do so will most continue and modify their approaches as their tastes dictate later.
ken