Well, okay, maybe not meaningless.
But.
I have been doing some thinking and experimenting, lately, and it led me in a surprising direction.

Everyone knows the dogma. You adjust the grind and dose to achieve a shot that blondes at 25-30 seconds. A finer grind leads to a darker, more concentrated extraction with a dramatic blonding point: a ristretto shot. A coarser grind gives a larger volume and a more honey-colored shot with a subtler blonding point, probably because the dark colored coffee solutes are dispersed in a larger volume.

Then one day I had a coffee that seemed to be incomplete at the endpoint. Now, I have gone through and tasted small fractions of the shot throughout its progression. I have also purposely omitted the beginning fraction, pulled center cut shots, and ended shots progressively early -- all this to get a sense of what different parts of the espresso shot contribute to its overall character.

It's no surprise that the beginning and ending fractions need to balance each other out, with sour and bitter sort of canceling each other to make a sweet shot. What was surprising was that one day I had a coffee that blonded at 25 seconds but which seemed like I had cut it off too soon. Exploring the extraction space, moving the temperature, shifting from a ristretto to a lungo: none of this was exactly satisfactory.

This made me think about what happens as an extraction progresses: the volume increases, the solute load is dynamically changing, and the pH is gradually moving. At a certain point the dark-colored solutes are thoroughly washed from the coffee grounds in the basket: the blonding point.

However, if you have ever done a chemical extraction, you know that you don't just pay attention to the obvious precipitate. It may be an impurity, it may not have the same pKa as the molecule you are trying to isolate, etc. Now, given that an aqueous extraction of coffee is fairly invariate, BUT just like an Ethiopian Harrar doesn't taste like a Panama Esmeralda, there are going to be some differences.

So, I tried going a little further: 1...2...3... finally 5 seconds past the blonding point where I would have stopped. And the cup finally became complete, the espresso was sweet and balanced. Going back and looking at the weight of the coffee grounds and the weight of the final extraction reveals a correlation to brew ratio paradigms that support the concept of using volumetric dosing versus time or blonding point as and end point of the extraction.

And, yes, I know it has been discussed previously, albeit perhaps, obliquely. I thought I would see what other people thought of this more pointed attack on the paradigm. I suggest that while the blonding point may be a good starting point, it may require additional adjustment to find the correct ending point for a particular blend of coffee beans.

Or do we need to go further and dispense with the blonding point, focusing instead on volumetric dosing, measuring weights and brew ratios?

Heather Perry is famous or infamous for running her shots way past the blonding point. Being two time US barista champion, and getting the nod for best espresso at the World championships indicates that this is sometimes the best way to go.

Her style is to dose quite heavily with medium roasted coffees that have a good deal of acidity. When I run Klatch's blends, I usually dose lower and stop more conventionally. I get a good result, but I don't get the pop her shots have. By going past the blonding point, she can balance out the extra acidity and bright bitters (lemon peel, wood, etc) that such a high dose can create, but still end up with a more distinct shot. But this technique may be a high wire act; at least, every time I've tried it, the resulting shots were not pretty.

In any case, for those who want to work this technique out, Klatch's blends may be a good place to start.

another jim wrote:Her style is to dose quite heavily with medium roasted coffees that have a good deal of acidity.

Well, that sounds like the blend in question in my case, so that is consistent.

It is a simple observation, but the dogma is the starting line not the finish line.

drdna wrote:Or do we need to go further and dispense with the blonding point, focusing instead on volumetric dosing, measuring weights and brew ratios?

drdna wrote:It is a simple observation, but the dogma is the starting line not the finish line.

The blonding point is a good guideline, especially for beginners, but it's not infallible. Precisely measuring the dose and calculating the resultant brew ratio is an excellent way to assure consistency and provides a good way of comparing notes more meaningfully with others; at least for me, it's nothing more, nothing less.

For what it's worth, I consider the "pucker" a more reliable reference point than blonding. I cut off most extractions 5 seconds after the cone collapses, though I may go a bit further if the stream still isn't showing any signs of translucence. See When did this espresso extraction go blond? for more details.

I think it depends on your definition of "blonding point".

I've noticed that many people think it's far earlier than it actually is (thanks James H for that point). This seems to be particularly common when people use a bottomless portafilter.

And, of course, the optimal stop point depends on the coffee rather than just the colour of the stream (ie you cannot generalize across all coffees).

I have found that espresso blends with African coffees benefit from terminating shots that have run into lighter colors. The association I have made is with my perception of the acidity in these coffees. If a particular blend, or single origin, comes across sharply acidy, the first thing I try is a longer pull.

This concept really gelled for me when I witnessed a large group of professional metropolitan Baristas (mostly accustomed to ristretto shots) who where attempting to pull shots of an African heavy blend. They all tried to pull short shots with heavy doses. When I tried it long and light, it was sweet and well balanced.

One of the difficult aspects of learning to work with coffee is that the "sweet spot", aside from being a little bit subjective, is inherently a moving target.

drdna wrote:So, I tried going a little further: 1...2...3... finally 5 seconds past the blonding point where I would have stopped. And the cup finally became complete, the espresso was sweet and balanced.

Bravo Adrian, I suspect a lot of us have been letting shots run longer than the blonding point just to get a little more espresso into the cup. Your experiments reassure me that I am not sacrificing taste for volume. Thanks, Carl

malachi wrote:And, of course, the optimal stop point depends on the coffee rather than just the colour of the stream (ie you cannot generalize across all coffees).

To me, this is the key point - this morning, I'm drinking a blend made for a big dose and a ristretto pull. But I've definitely had some other coffees that wanted to be pulled a full 2 oz. from a double basket or even 1.5oz from a single! (Talking about volume as well rather than just color change to make the point that ideal extraction volumes can vary really widely.)

This is something that unfortunately seems to require a lot of experimentation, IMHO - the results from a particular coffee are not always what you expect. (At least for me - others with more experience may have gone to a place where intuition is stronger about such things...) When you start generalizing that a particular color or volume = overextracted, you may miss what some coffees have to offer.