jpender wrote:Even if? Of course such instruments exist.
If the instruments existed in a form outside of lab equipment that's a zero or two more expensive than the highest end grinders on here. I'm aware of trying ovens to measure TDS + suspended solids, potentially in two separate samples, one filtered and one unfiltered, so that you could know both things. Although I'm unaware of anything to measure the lipid content, but I'm sure there's some laboratory stuff out there.
jpender wrote:That's the standard dogma. Is it supported by evidence?
It is the only one of the elements that changes in necessarily track changes in extraction. And contribute the absolute bulk of what espresso is. You can easily try suspended solids only, lipids only, and dissolved solids only yourself.
Suspended solids are an absurdly nonsensical way to track extraction for taste, just try pouring a bunch of ground coffee in cold water. 100% extraction yield off of a measure including suspended solids, taste like gritty water. Probably provide some texture, which is important, but they don't have much ability to be a major player taste wise.
Can get some coffee oils by separating them with centrifuging, taste awful. They're not butter. And it's a very small percentage of the drink. They contribute something to the mix, but it's not the bulk of the coffee.
And can get very low oil espresso with a paper filter in the basket or by tasting the centrifuged espresso (don't taste VST filtered espresso, it has a bizarre chemical taste from the filter and can contain tiny shards of glass), it's a bit weird without the other stuff there, but it's the only component that's recognizable as espresso by itself. And the absolute bulk of the drink.
AssafL wrote:So I'd prefer to think of it as if :
Espresso = (Instant Coffee) + ("whatever makes it espresso and not Nescafé")
So that VST and Atago (after filtering) measure the quality of the Nescafé. Not it's other organoleptic qualities. Which I personally can't discount because I prefer espresso to other coffees always. I like my flavors big fat and heady. And Nescafé doesn't quite cut it...
There are several
problems with this. First of all, this assumes that instant coffee is using equal quality coffee, brewing it perfectly, and there is zero loss of quality in any of the flavor compounds during the instantizing process (I don't think anyone says you can't absolutely ruin coffee after it's been extracted). And VST and Atago before filtering are still just measuring TDS, they're just getting it wrong. Neither of them is measuring the other parts of the drink. They fundamentally can't.
And espresso is going to be anywhere from ~4 to ~15 times the TDS of other coffees. It's dramatically different from other coffees even without the oils and sediment. Seriously, metal filter Aeropress and French Press have those too and they're not espresso. Turkish has those in far greater quantities than espresso (I've done centrifuging of Turkish and espresso, the espresso has a little dot of sediment at the bottom of the tube and Turkish it's like half the tube) and it's still very much not espresso. Those are an important part of espresso, but they don't make it espresso nearly as much as the high TDS does.