TheSunInsideYou wrote:the first shot I pulled had developed bitters and ashiness from a pull that I felt was too far into the blonding. Then I pulled it a little shorter, with less blonding, and the bitters had all but disappeared.

It's due to other factors. If you do the basic test of separating the pour into different cups, first few seconds, the next few seconds, etc. you can get ashiness and bitterness in the final fractions if the machine heats up or increases in pressure. In a double boiler or a correctly tuned HX, the final fractions are mild tasting dark caramels, and nothing else.

There is at least one very simple truth to all the extraction stuff -- it is very difficult to overextract coffee. You need prolonged or high pressure exposure to temperatures above 95C. This happens by design in instant coffee plants and by accident in poorly designed HX machines and hot plate coffee carafes. Otherwise, not so much. On a proper machine, going to far into blonde just dilutes the shot without afecting the taste

As I said before, our warnings about overextraction were based on doing the intial tests on messed up Gaggias, Silvias, and HXs.

I hate that we get this kind of wisdom like this... I had no idea...

another_jim wrote:It's due to other factors. If you do the basic test of separating the pour into different cups, first few seconds, the next few seconds, etc. you can get ashiness and bitterness in the final fractions if the machine heats up or increases in pressure. In a double boiler or a correctly tuned HX, the final fractions are mild tasting dark caramels, and nothing else.

There is at least one very simple truth to all the extraction stuff -- it is very difficult to overextract coffee. You need prolonged or high pressure exposure to temperatures above 95C. This happens by design in instant coffee plants and by accident in poorly designed HX machines and hot plate coffee carafes. Otherwise, not so much. On a proper machine, going to far into blonde just dilutes the shot without afecting the taste

As I said before, our warnings about overextraction were based on doing the intial tests on messed up Gaggias, Silvias, and HXs.

Perhaps it depends on the bean as well. I have had some awful coffees from letting them run too long into blonding, and on others I've experienced as you have described. And this is on both very temperature stable machines and also reducing pressure/temperature commercial levers.

Thanks Jim. Cutting to the chase, as always. I need to revise my ideas about blonding affecting taste, although now that you mention it, I realize that higher brew ratios just tasted like milder and more diluted coffee. You've merely stated something my taste buds have been saying but my brain wasn't listening.

I've been thinking about this. I was wrong to dismiss competent people's observations on the ground that it contradicts my theories, and I apologize. Doing this is sure fire way to miss out on important discoveries.

On the other hand, I still couldn't see how the small changes in extraction or concentration that come from running a shot a little longer or less can make a dramatic difference. The taste of the final fraction of an espresso shot supports this difficulty in explanation ...

Then it hit me, good bourbon reacts in precisely this very odd way. The oak on some opens up with no water added, some need a drop of distilled water, while yet others need a splash. This has very little to do with the alcohol content. Does the water add a taste? Obviously not. Is it simply the overall "solubles concentration" of the oak aging compounds? If it were, the response would be lot more linear. Instead we are looking at a tipping process -- one drop more or less and the flavors either remain closed or open up.

Maybe coffee's bitterness works like that of bourbon. Just in case it does, this weekend, I'll play a little with ristretto and branchwater.

I think the confusion is that when you let a shot run longer, say well past the blonding point, you're also increasing the contact time. It's the additional contact time that can cause over-extraction and bitterness.

Put another way, if you grind too coarse, and the shot blonds very early, it'll be under extracted because there was insufficient contact time.

In both cases, the shot runs well past the blonding point. But one is over extracted and one is under extracted. So the blond color, by itself, isn't indicative of over or under extraction. That's determined primarily by the contact time, which is in turn determined by the grind and dose (like Jim said.)

[Notes for the picky: Contact time is also determined by system pressure and flow rate, but if those are fixed then the grind and dose determine flow rate and contact time. Also, higher temperature water will generally extract more, lower temperature water will extract less.]

I'm less certain about the effects of pressure on extraction, mostly because pressure and flow rate are intimately connected. Is it the higher pressure that causes greater extraction, or is it that the flow rate is reduced, thus increasing the contact time?

another_jim wrote:On the other hand, I still couldn't see how the small changes in extraction or concentration that come from running a shot a little longer or less can make a dramatic difference. The taste of the final fraction of an espresso shot supports this difficulty in explanation ...

Actually I don't see a big contradiction with my experience. I agree that the shot weight is far less critical than dose and grind.

What I meant was that after first roughly dialing in by blonding, I think I can get better shot to shot *taste* (not just weight) predictability afterwards by stopping at the same weight than by looking for the same blonding point each time. My ability to hit the same blonding point every time isn't that good.

So I'm still adjusting to optimize taste, not weight. But once in the ballpark by blonding, I find it easier make the necessary small ongoing tweaks to dose/grind by taste if I continue using the scale to lock down beverage weight.

No doubt others may be good at judging blonding very repeatably. I'm not.

Charles, Jim is speaking about what happens AFTER blonding starts. You're wondering about stopping the shot prior to or right at the first dramatic sign of blonding. It sounds like you're saying, regardless of contact time you're getting consistent in-the-cup taste, since you mention blonding doesn't always happen at a specific time. Just wondering, when you hit your ideal espresso weight, is it always happening at the same time?

Reason why I'm interested is that, after taking a sip of a great espresso, I've often wondered if it could have been even better if I managed the pull differently. For instance, could it have been even better if I cut it at 25 instead of 26. Unfortunately, I ALWAYS think it could have been better! lol

I have wondered about buying a refractometer, but I feel like it's this crazy expensive gadget that will help you understand the TDS level impact on taste and then it just starts collecting dust.

Several years ago tester extraordinaire, Andy Schecter, decided to make a device to test all the received wisdom about blonding and over-extraction. He bored out a plastic plank and set a series of shot glasses on it. He then pulled the plank while a shot was brewing to get a sample of each stage of the brew. His experience and I think the experience of everyone who did this was that the blond samples were not bitter and in fact had very little flavor at all.

Andy was nice enough to make a lot of "Schectermatics" and sell them as a benefit for Coffee Kids. I still have mine. Anyone in L.A. who would like to have it should PM me.

Spitz.me wrote:It sounds like you're saying, regardless of contact time you're getting consistent in-the-cup taste, since you mention blonding doesn't always happen at a specific time. Just wondering, when you hit your ideal espresso weight, is it always happening at the same time?

Yes, pretty much the same shot time. But I don't worry about that a lot. I just concern myself with the taste. And if one morning it's running a little differently, I almost invariably find a directly correlated taste shift and I tweak the dose or grind. I mostly hold beverage weight constant; I could substitute blonding point for weight but I have had better results with weight. Maybe just me; I'm not claiming to be an expert but I do get pretty consistent tasting coffee now.

Again, I totally agree that it's not at all critical compared with flow rate sensitivity and that the last part of an extraction is generally bland.