John wrote:The possible problem is that these experiences are with equipment that we have for sale. And therefore anything I say may be thought to be advertising. I hope that I don't transgress here...
Not to worry, that hasn't been a problem to-date because the participating sponsors / professionals understand the difference between sharing information and promoting their products. While there are no formally published rules for the board yet, Team HB has collectively created a mission statement and guidelines in the spirit of moderators as your hosts and discussion facilitators, not enforcers. Since moderatoring in the common use of the word hasn't been necessary (*knock on wood*
), I've seen no need to post rules.
It is our feeling that these are not minor flavor changes. We have learned, just this summer, about just how sensitive this process is. We were getting lots of variations in the cup that we thought was the natural result of the variability in the beans from one shot to the next or one day to the next. What it was was the small variations in brew parameters that we didn't imagine would affect the flavor, and that we therefore paid no attention to from shot to shot or day to day. Now we have serious repeatability.
We are not imagining things - nor exaggerating - when we say that the flavor change of .05 bar on the M3, 100 rpm grind speed on the M3 grinder, or 1-2 degree change on the Sivetz roast temperature on one of three beans in a blend - is a very serious flavor change. Any single one of these can make or break the flavor in a cup. And any one of these is repeatable.
I consider myself an average espresso lover and thus assume such minute subtleties would either be beyond my abilities to detect or acceptable variance. To put it in basic terms by way of example... I like red grapes more than white grapes, but I'll happily eat either for lunch. But if I'm really in the mood for grapes and we only have bananas in the house, well, I'm disappointed. I am struggling to grasp if the differences between such minute pressure changes would mean nicely ripe bananas, hard green bananas, or simply red grapes / white grapes. I don't mind a little serendipity in my espresso as long as it's within an acceptable range. In contrast, based on the writings of some professionals, I imagine them flying into a rage if the temperature is off by 0.4F from the previous extraction. That's not me.
More seriously and directly to your point: Is the tight control you describe within .05 bar of a fixed pressure, or do you intentionally vary pressure through the extraction to produce a "pressure profile"? Jim Schulman postulated on the positive effects in Received wisdom about brew pressure
(excerpted below) and I'm wondering if his findings are consistent with your own.
another_jim wrote:There's two disputable assertions on lever groups - that they have greater clarity and less crema, and that the reason is lack of vibration.
The first is an oft repeated observation -- I get it reliably and invariably when I set the La Peppina and Tea side by side, Mark mentions it in the Elektra review. Almost all owners of lever machines, home or commercial attest to it. Obviously, it could be wrong, but it's about as solid as any other fact in this game.
The reason for it being lack of vibration is mostly unresearched. I was the one who raised the pressure profile as an altrnative possibility; and, so far, am the only person I know of who's tried it. Most people just don't have big variacs lying around into which they can plug their machines or pumps. of course, even modified the E61's profile has the 10 second ramp up, so that's still a point of difference to the typical lever having a no pressure presoak for around the same length of time.
Thinking about this. I guess there's a lot of received wisdom about pressure, most of it virtually untested, and perhaps wrong. The knowledge about temperature variations is hugely more reliable, since adjusting temps is a part of lots of people's daily shot making practice. Adjusting pressure is usually done for maintenance or gross defects, not taste adjustments. So there's several orders of magnitude less data on it.