Bob Barraza wrote:Once the brew water hits the coffee in the basket, it is hard for me to see how it could continue any laminar characteristics. To me, it seems that diffusion would better describe the process. In either case, channeling is the enemy.

I don't recall the exact numbers, but during the extraction we are removing between 10-15% of solids by weight. Regardless of the exact number, as we dissolve material from the ground coffee during the extraction we are increasing the porosity of the grounds and the coffee bed. If the pressure is kept constant, the reduced back pressure will increase the flow rate. This will increase the chances of channeling and probably lead to over-extraction.

Perhaps the ideal machine will not only control pressure but flow rate as well.

maximatica wrote:But here are my 2 new points;

A)

I think the reason singles taste better than doubles is the shape of the basket. They are all shaped pretty much the same from maker to maker and I think the reason is that the shape makes the best tasting espresso. It is obvious that a shorter version of the double basket would be cheaper and easier to make.

In a single basket the coffee is forced together at the outlet and that mixing may be the secret. Also since it is conical shaped it has to have some venturi effect with the water flow accelerating as it moves through the coffee grounds.

It is obvious to me that the double basket is the cheapest way to double coffee production and was never meant to be considered the equivalent of 2 singles. The trade-off in taste for the doubling of production in a cafe environment would be totally justified.

So those who think a double is where it's at need to re-think. If your singles don't have a more nuanced flavor compared to your doubles you need to work on that. There's a reason single malt scotches cost more than blends and generally have less "body".

B)

I think the reason lever machines and the Semi make better coffee is that the water path is straight down through the coffee with all the coffee getting the same pressure and water flow. On E61 (and similar) machines the water enters at an angle and I can clearly see on my Isomac that there is flow closest to the water inlet before there is flow across from it. This happens on both the single and the double baskets. So there is not even pressure throughout prior to flow.

Between my points A and B above I think you will find the answer to the Semi's better coffee production and why a quality company like Elektra would put out such a machine (which defies all logic according to the coffee-tweaks) year after year.

Elektra may have adopted a sales approach similar to Apples old (1980-1997) policy. Us Mac owners were always incensed that year after year they would just keep saying "it's better" instead of laying out the benefits one by one (with their new policy they have taken a little bit more aggressive approach).

Elektra may have the policy of "if you can't perceive the improvement, then maybe you shouldn't buy it" rather than spelling out the reasons why it works better. Also, I can see that Elektra does like to file for patents to protect their technology. But if they know they can't get a patent on their process then keeping their mouth shut is the next best thing and that may be why they don't say "see, here's how/why we do it".

Anyway, when friends ask why I will be selling my Millennium and getting a Semi, I point out that it looks like the espresso machine Flash Gordon would use and that that's enough reason for me .

M./

cafeIKE wrote:If the espresso tastes better, please, DON'T tell!

cafeIKE wrote:Please, solve this mystery before I have to buy one...