Blog : roasting

Water and Chemistry

Water and Chemistry

This article was originally written by Matt Campbell for the membership of Coffee Props.  Please visit www.coffeeprops.com to join the conversation and be a part of the community!

So much focus has been put on the coffee itself, and rightfully so. The grind size, consistency of grind, freshness and quality of the bean, roast quality and method of brewing are all important factors when considering the end result of your brew. Traditionally when we would talk about water we would be discussing water to coffee ratio, temperature of brew water, speed and type of infusion method, and filtration. While these factors are all important, recent studies have broadened our understanding of our water.

 

What can be so complicated? Water is H2O, right? Well, yes; and no, not always. Without getting too deep into the physics and chemistry of it all, water is made up of hydrogen and oxygen atoms, and the liquid we all know and love is capable of dissolving all sorts of other molecules. The makeup of water depends on a multitude of factors and conditions, and it is a complex array of chemistry and physics. Each water sample can react differently with its surrounding environment, and it is no different when we heat it and pour it over a bed of coffee.

 

It has been shown that magnesium (Mg +2) and calcium (Ca +2) are important to extracting flavor from coffee. These two atoms readily dissolve in water to create ions. These ions have a charge, which reacts chemically with flavor in the coffee to extract it into solution. Adding the sum of these two minerals together to calculate their abundance in parts-per-million (PPM) will give us an idea of general hardness, or GH.

 

On the opposing side of these ions are carbonate ions (HCO3 -1), which is more commonly referred to as the alkalinity or buffering agent (KH). This also contributes to coffee flavor, but it must be kept in check to prevent undesirable changes.

 

Although there are other minerals and ions in solution, the three mentioned above are the most important factors that impact flavor. These ions must be kept at the right level of hardness, but they must also be in proper quantities relative to each other. The preferred ration seems to be 2:1 in favor of the general hardness when the GH is around 100 ppm.

 

Believe it or not, that was actually a pretty dumbed down version of the whole story. Although these are just the basic facts, there is a whole textbook of information called, “Water for Coffee.” If you are they type that needs to know more, there is no more relevant and thorough information available. It isn’t exactly an easy read, but it is articulate and complete.

 

All this fantastic information has been made available recently, but now what can we do with it? Sure, we can purchase titration test kits and expensive filtration solutions to make the perfect water for coffee, but for the average household this is not a feasible option. Is all lost?

 

Not quite. The chemistry may be complicated to understand, but some very smart people have broken it down for us. Matthew Perger, WBC all-star and coffee guru has been dropping knowledge for us, so I will yield the floor to his recipe for perfect water:

 

Water Recipe:

 

Based on instructions from Matthew Perger, and the book Water for Coffee

Ingredients: Sodium Bicarbonate (aka baking soda); magnesium sulfate (Epsom salt); distilled water

NOTES:

  • Distilled water, spring water, and purified water are not the same. It must be labeled distilled for this to work.
  • The Epsom salts must be unscented, and read magnesium sulfate. MgSO4

 

INSTRUCTIONS:

 

To make concentrate:

  1. Add 8.6g baking soda, and 25g Epsom salt to 500g distilled water. This is your concentrate.
  2. Shake this concentrate until it is all dissolved.

 

To make perfect coffee water:

  1. Place 500g of distilled water into a clean glass container.
  2. Carefully mix 2.5g of CONCENTRATE into the distilled water.
Coffee Rating

Coffee Rating

This blog post was originally written by Matt Campbell for Coffee Props.  Coffee props is a community of coffee lovers, with a focus on bringing clean water to third world countries. Check them out at http://www.coffeeprops.com for more!

How does your coffee rate?

 

Coffee is everywhere. It is ingrained in our culture, and our daily lives. From fast-food drive-through to your kitchen, chances are that you aren’t far from it. As part of Coffee Props, our main focus is on that small percentage of coffee that is considered “Specialty Coffee.”

 

Specialty coffee is defined as the best of the best in the coffee world. That doesn’t mean much without a way of quantifying, or grading coffee. Thankfully, the Specialty Coffee Association of America has stepped in to help create a standard so that the coffee industry can define Specialty Coffee exactly.

 

Let’s get nerdy.

 

The SCAA developed a system called “Q-Grading.” This is a series of metrics that will help the industry to grade different coffee against each other, to discover what makes the cut to be considered Specialty Coffee. Q-grading combines both objective and real measurements with subjective sensory traits. There is a very rigorous training program for those who wish to become Q-graders, and it is an ongoing training once that certificate has been earned. Graders must ‘recalibrate’ to each other frequently, to make sure that they are all in agreement on the results of a coffee even while they are in different countries.

 

This program is actually so well managed, that Q-graders are able to get results +/- 1 point of each other. This is over a system of 1-100, so the margin of error from one q-grader to another is 1%. That is a tremendous feat.

 

So what does Q-grading do for the coffee industry?

 

Coffee isn’t grown in most regions that are consuming the beverage, so it is important that a system is in place to buy, import and roast coffee from around the world. If a buyer in Brazil is grading a coffee, they can relay that information to an end user in the US, and they can decide if they should purchase that coffee, or look for another. When the coffee is received stateside, we can feel confident that we have made an educated purchase.

 

Great, Q-grading is for buyers, and roasters. What can it do for YOU?

 

Q-grading does not end with industry professionals. There are resources for roasters to submit their roasted samples to a company, who will blindly taste the coffee and give it a grade. These are called sensory evaluations, and they are a great way to convey to consumers what they can expect prior to buying a product. The largest and most respected resource is Coffee Review. Coffee Review regularly does grading for roasters around the world, and they publish the results for their consumer base. This assures buyers that they are getting a high quality product, and it can even help you find some great coffee that you may not otherwise have known about.

 

By the Numbers

 

Can we get a frame of reference for these numbers? Any coffee that is rated by 80 or above defines Specialty Coffee. This rating is assigned at the point of purchase, by Q-graders. This doesn’t mean that your roaster will take a 90 point green coffee and roast a 90 point final product. In fact, it is quite possible that they won’t even come close. Many factors in the roasting process can affect the final product, and this could cause a much lower grade. It is also possible that a lower-graded green coffee can be treated perfectly by the roaster and surprise us all with a great grade.

 

It is a huge accomplishment to have a coffee achieve a 90+ rating, and you can see some examples of that by checking out some of the ratings on coffeereview.com.

 

(shameless plug)

At Branch Street Coffee Roasters, we recently decided to send our first sample of coffee to be professionally graded. We did this to gauge our roasting, and to ensure that our product was standing up to the quality that we are consistently trying to achieve. We were more than satisfied with the results, and it has given us a metric to strive for with all of our coffee. We can promote that coffee to our clientele, and they now have an expectation by seeing that number. It also encourages us to keep striving for the high ratings, and continue sending samples to ensure that we are always earning that mark.