another_jim wrote:If cation treated water flows more slowly, it can be compensated for by setting the grind finer.

Jim, I've been meaning to ask... Did you mean coarser?

Sorry, brain fart. Very soft water is slow extracting, but also has less body, so neither coarser nor finer grind will work well. Softened water extracts more slowly, but has plenty of body, so coarser grind will work fine.

Prior to this publication, the recommended choice of either RO or cation softener treatments depended on the local water hardness. When the water is very hard, RO membranes become very inefficient and expensive, so the recommendation was to use salt softeners. This is true for most of Italy or anywhere else where the drinking water comes from limestone stream beds, aquifers or wells.

There is a very good argument to be made that any cafe chain or roaster selling to multiple commercial clients should specify a standard water composition. This is part of achieving consistent quality. My beef with this piece is that it appears to conflate this clearly legitimate claim with the clearly illegitimate one that the same standards should apply universally, to all roasters, coffees, prep methods, taste and market segments, economic circumstances, etc etc.

another_jim wrote:There is a very good argument to be made that any cafe chain or roaster selling to multiple commercial clients should specify a standard water composition. This is part of achieving consistent quality.

Would the same argument apply to things like CoE auctions and barista competitions? It would seem so.

Best,
David

Perhaps the point was already made and I missed it, but even with RO, you must first pretreat the water with a softener, especially if the water isn't naturally soft. The reason for this is that Calcium and Magnesium precipitate out (hence the scale buildup in your boiler) and clog the membrane. The ionic exchange of a softener replaces the minerals with sodium or potassium to create the appropriate carbonate. An aqueous solution of sodium carbonate requires a much higher concentration in order to precipitate out.

Reverse Osmosis is different than your standard filter in that it processes twice as much water as it gives you. Half the water processed is delivered as RO water to your pressure tank, and the other half is split-out (grey) water that runs down the drain. Any molecules that precipitate out before the RO membrane eventually clog it. Salts (ions) pass into the split-out water based on the efficiency of the membrane (92-99%).

One type of softener that I haven't yet explored is the crystalline bed (no salt needed) softeners that are supposed to rearrange the calcium or magnesium carbonates into a non-reactive crystal form. Does anyone have experience with those?

another_jim wrote:Interesting point. Coffee is a strong flavor, so a difference that would be readily apparent in the plain water will be obscured in the presence of coffee. Therefore, they are claiming that a 25 mg/L will tasteably affect the way the coffee extracts, not the way the water tastes.

The coffee newbie theoretical question:

Does water hardness changes what is extracted out of the coffee bed? I would think so.

If so, then is it possible that the taste difference one could discern would not be directly caused by the coffee water hardness but rather from the difference in extraction, caused by the difference of hardness?

Could a small change in hardness, undetectable in taste test, become detectable in coffee?

I have taken the liberty of responding to a slightly broader question than the one that you have posed, above

I have no background in water chemistry, nor in the extraction of the various compounds found in coffee, as is effected by the composition of water. I do have a little bit of experience in scientific research, and some experience in blind tasting studies, much of which is to be found posted on this internet website. But I digress.

Coffee is a complex organic product, that contains hundreds of flavor-related molecules (probably more than hundreds), some of which are water soluble and some of which are dissolved in coffee oils. There are many different types of coffee, and one can imagine that the frequency and composition of these molecules will vary across different coffees. There is, beyond question, a lot of interaction between the coffee itself and the water used to extract it, that will vary based upon the chemistry of the water. Some of this variation will be tastable, and some of it will not. There is also going to be an impact of pressure on what gets extracted, in that brewing at normal atmospheric pressure, as in a filter cone, will extract somewhat different things than get extracted under the lower pressures of a lever machine, or higher pressures (around 9 bar) of a machine driven pump espresso machine.

There is obviously the makings of an enormous research experiment that could be done trying to figure out what is important in this whole matrix and what is not. To my knowledge, no one has attempted to do such a study as it relates to the hugely variable water supplies one encounters around the world, no less across a much smaller region. Such a study is not practicably doable unless you eliminate a whole lot of the variables by simply assuming they are not important.

There is no incentive for anyone to do a study as I have alluded to above. So the short answer to you question is, "who the hell knows?" Or, at least no one knows if you were starting out with a whole collection of untreated tap water samples obtained from various locales, because these water supplies are not going to differ by just one or two ions or molecules. Given the fact that numerous things will vary, it will be hard to put your finger on exactly what was the one thing that mattered above all else, assuming there is an interaction amongst these dissolved things found in water.

Being as there is no real incentive for real research that would have no economic payoff, all the work that has been done centers around those few things that do have an economic or practical application. Number one among these would be the propensity of calcium carbonate to precipitate out inside of coffee boilers if the water used has "too much" of it. This calcium carbonate scale is a huge PITA (chiant ) and has to be mitigated with "descaling" or the water needs to be treated in some other way to prevent this "scaling." Hence, cation softening became popular a long time ago in places with naturally hard water, as a simple way of preventing or reducing boiler scale, while still producing good results in at least some cases with some input waters.

Another possible way to treat the water is to deionize it, by Reverse Osmosis (RO), distillation, or whatever. This causes two problems; (1) deionized water tastes flat and the coffee produced from it is sub-par; and (2), modern espresso machines with autofill circuits require some minerals in the water in order for them to detect that the water has reached the desired fill level, e.g. to complete the electrical circuit with the probe.

Since it did not take brilliance to determine that deionized water is not suitable for coffee preparation, that has spawned the current industry of water treatment for use in making coffee at commercial establishments. All of this is operating on the free-market profit model; that is to say there is no real "pure research" being done to try to figure out what is best, rather the relatively simple stuff that can be studied and manipulated and customized in a working commercial environment (such as a cafe) has been the focus of all the attention.

And this is how we got to where we are today, at least in my opinion.

ken

Louis wrote:Could a small change in hardness, undetectable in taste test, become detectable in coffee?

The conventional wisdom, found in fogey old refereed journal articles, was that this is true when the water is very soft, 50 TDS and lower, since percolation beds (e.g the puck or the coffee in a filter) get slimy and fouled with very pure water. This is in the food science literature about making instant coffee, where the percolation columns are 10 feet high and the coffee circulates under pressure for several hours (After reading this stuff, you will need to do purification rituals to the coffee gods, or something else that's drastic, to get the imagined taste out of your mouth.)

Here in a nutshell is the story of the new standard

The old SCAA, and the existing SCAE, NCA, and ICO standard for taste is not based on TDS but on neutral hardness, 90 mg/L calcium, which can coincide with anything from 90 to 180 mg/L TDS of natural water, depending on what's in the water.

However, very few cafe owners use this neutral hardness standard for espresso, since it scales the machines. Therefore, companies like Cirqua produce "designer waters," by adding a mineral cocktail to RO water. This mineral cocktail contains both mono and bivalent anions and cations, which gets the water up to about 150 TDS while keeping scale forming bivalent ions at a lowish level, so that the water is softer overall, and the machines have longer descaling intervals.

Everybody grants that these cocktails, when well designed, can perform slightly better than salt softened water or an RO system with a calcite filter. But the new standard, mirabile dictu, finds that this 150 TDS designer water cocktail also makes the absolutely best tasting coffee. Outside of the universe of advertising, it is rare to get all ones wishes and needs granted with the purchase of one product.

Since a company which makes 150 TDS designer water is the author of the standard, there is a reasonable suspicion that unlike the standard it replaces, and which every other coffee body still accepts, it will not pass muster if and when it is peer reviewed.

Jim,

That is the most well-reasoned and least inflammatory response I've seen in some time. I understand that the position of Mayor of Chicago is opening up. Coincidence?

David

DavidMLewis wrote:. . . well-reasoned and least inflammatory . . . I understand that the position of Mayor of Chicago is opening up.

What do reasoning and noninflammatory statements have to do with politics in Illinois?

DavidMLewis wrote: I understand that the position of Mayor of Chicago is opening up.

It's scary to think about. The Daleys managed to create the same two party system inside every Chicago ethnic community: the pro and anti-mayor parties, and siphon enough clout to the pros to keep them on top. This prevented most of the inter-ethnic BS that sank other US cities by suburban flight of old residents and avoidance by new immigrants. Lets hope there's no longer any need for this very high level of cooptive skill.