..so much as some musings on espresso extraction.

As I understand it, espresso was invented as a means of extraction so that it would reduce downtime for workers at a factory in Italy. The owner of the factory (and inventor of espresso) clearly kept an eye on the pennies. So in essence the reason espresso came into being was to reduce costs.

I've been exploring the notion of cost reduction and wonder how far that thinking can be applied to espresso preparation.

The first most obvious point is that espressos use less coffee. Drilling down a bit it can be seen that in order to get the most use-able liquid out of a particular weight of coffee, you have to increase the surface area that is in contact with water. IOW if you use (relatively) large lumps of coffee it's fairly clear that a lot of your valuable resource is not extracted, and is therefore under-utilized waste. So to save money the grinds should be as small as possible - leaving taste aside for just now.

Next comes the issue of what amount of coffee is necessary to make a drinkable brew and what can be done to reduce this to a minimum. Clearly the less coffee used the better - if we're talking cost reduction. But too little coffee leads to a weak watery brew, that pisses off the workers and so productivity falls, increasing costs. And using too much is wasteful.

One determinant of extraction efficiency is the length of time the water is in contact with the coffee. Water will flow through a larger volume of coarse grains at the same rate as a smaller volume of fine grains. There has to be a point at which the two extraction times are equivalent. Therefore it ought to be possible to use less coffee to get the same flavour as more coffee.

A determinant of water flow through the coffee and therefore the amount of time taken for the extraction is the density of the grind that it has to flow through. That density may be increased by increasing the force used to compress the grains. Therefore by increasing the pressure of the tamp you can use even less coffee but still keep the extraction equivalent to a larger quantity of coffee at less pressure.

So now the limit has been reached for the absolute minimum amount of coffee that can be used. Unfortunately the grind is now so fine and its compaction so great that water will not now flow through it. Hence the need for 9 bar pressure and pumps etc.

So should cost reduction be the engine behind dose setting? That is you start from the point of finest grind, smallest quantity of coffee and maximum tamp pressure and work back from there until you achieve at taste that you like?

I think the inventor of espresso would probably approve.

i was under the impression espresso was invented in order to produce coffee faster, not use less of it. i could be totally wrong, but

Ian_G wrote:The first most obvious point is that espressos use less coffee.

is this really true? i use 18g for my doubles and 18g for my 8oz drip. espresso being the faster (and preferred) method.

Cost cutting?
How much did a brand-spankin'-new espresso machine cost back then compared to a bulk brewer?

How about training a barista to get a decent extraction?

I use less coffee for my non-espresso than I do in my espresso... but if we're looking at 'traditional' dosages then, perhaps, for coffee. I still think coffee would have been cheap when compared to the cost of the machine and training. Perhaps the turnover due to the serving speed and freshness could make up for it, but bulk brewing coffee would probably have been the cheapest...

You're right about the need for speed. I was thinking that if he was laying on coffee machines at work, he'd be supplying the coffee too.

Just yesterday and today I started grinding a lot finer, to the point I am using half a basket for a double. So I've saved 50% by volume on my shots and I think they taste better too. Although I take on board your point. I'm just thinking out loud here and posted really to find the holes in my argument, such as it is.

I'm not sure about coffee being cheaper in relative terms, since there would have been far fewer suppliers in those days. Of course consumption would have been a lot less too. One stat that I did notice was that coffee was at its cheapest in 100 years as recently as 2004.

7 grams is standard coffee serving size. Those coffee measuring spoons give you 7 gram per cup or, 56 gram per litre.

another_jim wrote:..... but the concept had been proved, and the race was on for a mass brewing machine that was both fast and tasty.

Poor factory workers were not the target audience, but rather the crowds of more affluent people at the shiny new railroad stations, arcades, and Haussmann boulevards

Thanks for the historical back drop Jim. So after 1901, coffee retailing quickly became a much more viable commercial venture. Once you go commercial then there is the need to control costs. In a survival of the fittest kind of way, assuming all equally tasty, the venture that has the lowest costs makes the most money and can expand the fastest.

Given that it was only the well heeled that could afford the stuff in the beginning, then the costs associated with producing the drink must have been high. I suppose that competition between machine makers would have helped to drive down costs, as would increasing the production and supply of coffee. However this downward pressure on retail costs would be slow to appear. A much more instant upward pressure on price would be a cut in the supply of coffee beans due to bad harvests/adverse weather. So from this perspective, at least in the beginning, the supply of coffee would be the biggest determinant of retail price. Things like labour, rent and rates etc would presumably be fairly constant.

If demand for coffee outstripped supply, then the price would rise. The question is: did demand for coffee outstrip the speed at which new plantations could be conceived. Probably, sometimes it did and sometimes it did n't.

So coming back to my original "theory". Was cost reduction the determining factor behind dose setting? That is they started from the point of finest grind, smallest quantity of coffee and maximum tamp pressure and worked back from there until they achieved a taste that customers liked?

And should we do likewise?

An excerpt from a review I did a few years ago...

Back in the late 1800 to early 1900's, the first pressure brewing methods were emerging. These pressurized percolators earned the moniker of 'espresso brewed coffee' due to the reduced percolation time and individual serving capability. The coffee was brewed 'expressly for you' one cup at a time. These early espresso brewers used steam to generate the brewing pressure. Unfortunately, that steam not only accelerated the percolation of coffee but burnt the coffee due to the high temperatures and direct contact of steam with the coffee grounds.

In the 1930's Sr. Cremonese patented the screw piston mechanism. This allowed for manual pressurization of the percolation group. The high pressure steam no longer came in contact with the ground coffee which greatly improved the taste of the coffee. In 1938 Achille Gaggia applied for a patent for the rotative screw piston group.

Mr. Gaggia never perfected the screw piston group. The design, while an improvement on the older steam pressure machines, still had many mechanical flaws. His next idea was to use a spring powered vertical driven piston. The spring would provide constant pressure to the group piston. Achille Gaggia discovered that using a consistent and fine grind in conjunction with the spring powered piston he could percolate a 'short black' in 15 seconds. The increased pressure also created a reddish brown froth; crema was born. On August 8, 1947 the spring assisted 'espresso machine' was patented, laying the foundation for what we now call espresso.

Bluecold wrote:7 grams is standard coffee serving size. Those coffee measuring spoons give you 7 gram per cup or, 56 gram per litre.

I think I might be flogging a dead horse here as there does not seem to be any readily available information about dosing pre-espresso or pre 1950's when the NCA set todays guidelines.

Still it seemed like a good idea at the time.