29 August, 2011

h2o: pt. 1

I've been long thinking I need to write something about water. If not for my own need to organize all the data floating around in my head then to help make clear what, in my opinion, can be an exceedingly complicated variable in regards to the brewing of coffee. Please don't judge me...this is not an academic/researched article and I'm not a chemist. It is somewhat scientific but a bit more anecdotal and meant to hopefully clarify a bit something that we all kind of go fuzzy on after a few acronyms have been thrown out.
It is ironic though because water is THE most affecting variable when it comes to the extraction of your coffee. And isn't it a bit odd that we spend literally thousands of dollars on temperature and pressure stable (controllable) water delivery systems,100's of hours perfecting pours so that turbidity doesn't over-extract coffee and yet water is sometimes barely a passing thought? We should start with water, then go from there.
My real education in water began when I moved here in Feb. of 2005. I moved from a city that arguably has some of the best drinking water in the nation. Fed mostly by the Cedar and Tolt Rivers, Seattle, WA has water that is relatively clean and soft compared to Madison water which is very hard...and depending on the area of the city, pretty heavy in particulates. Softness and hardness in water is a reference to the amount of dissolved minerals...mostly calcium and magnesium, but iron, aluminium and manganese as well. The softer the water the lower the presence of these minerals...the harder the water, the higher amounts of mineral content. The more stuff that is dissolved in the water, the higher the Total Dissolved Solids (TDS), measured in parts per million (ppm). When water changes forms (liquid to solid or liquid to gas) these dissolved solids can solidify...thus the presence of white dust in your tea pot or white flakes from your melting ice. Since we like to heat water in the coffee industry, this presents a bit of a problem for more than a couple of reasons.
Seattle/Madison Water Specs:
Calcium: 17.0 ppm/69.0 ppm
Sulfate: 2.0 ppm/16.0 ppm
Magnesium: 1.0 ppm/41.0 ppm
Chloride: 4.0 ppm/13.0 ppm
Sodium: 4.0 ppm/8.1 ppm
Bicarbonate: 18.0 ppm/110ppm
PH: 7.8/7.4
The above numbers will hopefully mean something if you labor through the rest of this article...but suffice to say, Madison has dramatically different water than Seattle. What I started drinking (and brewing with) when I moved here was radically different than what I came from. I also had to start feeding salt to the monster in the basement called a softener. I didn't really get how adding salt to water helped with anything, but after a few months in the coffee industry I started to understand very quickly what happens to our water when it gets heated and boiled to make coffee...and what we do to it before it even gets to the boiler. Today, I spend most of my time servicing and repairing coffee brewing equipment. I have become quite a pro at figuring out ways to remove mineral build up or blockages from tiny orifices so that coffee tastes good, but I'm still confounded by water, the most abundant and life giving substance on earth.
Specific water chemistry is highly regional. We start with water, which in its pure form is a chemical substance made up of two hydrogen atoms and one oxygen atom. But water doesn't really naturally exist in its pure form. Due to its nature to be highly solvent (dissolves other things) water ends up containing dissolved mineral solids it picks up from the environment around it. We use TDS to describe how much has been dissolved into the water. TDS does not tell you what is dissolved, but it does tell you how much. If you know a thing or two about where your water comes from then TDS can be a very good way to make some judgments about your water. Here in Madison it can range from around 400TDS to as high as 600TDS in some neighborhoods. Distilled water is at 0TDS...
So what does this all have to do with coffee?
A couple of things really. Most basically, it affects what the coffee tastes like because the specific TDS and relative hardness affects waters' effectiveness as a solvent and therefore to extract or take on flavors of the roasted and ground coffee. Second, and maybe just as important, when we heat water, the dissolved minerals in the water turn into a solid. This substance is usually referred to as scale, limescale, calcium, rocks... When this happens inside your water boiler on your espresso machine, or the tube that carries water into that boiler, or the valve that opens up to dose the water or a myriad of other inconvenient places, you get a breakdown. (This usually happens at 8 o'clock on a Friday morning when you have a line of customers out the door). So, to avoid this, we apply a number of chemical principals in the form of filtration to either keep the dissolved minerals from solidifying or remove them all together. Depending on what method is chosen the water chemistry is affected and therefore coffee flavor will also be affected. I'll really get into this, but first I want to talk about the regionalism of water again...and beer too.
In my move to Wisconsin I quickly adopted the proud past-time of drinking lots of beer (not super into the Packers yet though). I like beer. I'm a seasonal drinker like most, preferring Ales in the Summer and going darker as the weather gets colder. I don't brew beer but have hung around enough people who do to know that specific water chemistry has a huge affect on beer flavor/body (probably more so than on coffee). As I understand it this is one of the reasons why there are international differences in beer...and why one can't really brew a proper Belgium beer in Wisconsin. The locality of water has helped shaped the cultural identity of many noteworthy beer-brewing regions. I'm curious if there is a validity in this reality as it applies to coffee brewing. My gut says no. I think there has been some discussion..and the SCAA has, to a vague degree, made an international stance by considering a TDS limit when defining the “Golden Cup” whatever that is... The specific water chemistry certainly affects the coffee and how it tastes but, in my opinion, the absence or presence and level of these substances in the water will not set a coffee's brew-locality apart from another. It will change the flavors/extractions, but not in a regionally important way. Furthermore, as roasters are assigning best extraction ratios and water temp./pressure, coffee in/liquid out proportions, it seems obvious that there should at least be a standard for water chemistry.
The real sad part here is that I know of only one roaster in Wisconsin that is actively testing (or playing with?) how changes in specific water chemistry effects the coffee's flavor. I think we owe it to the specialty coffee industry to start weighing in on the chemistry of the water we use to brew with and the effect it has on the extraction of our coffee.
So, with that said...what should we do...and what do we do to our water so we can brew great coffee?

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