SCA BREW STANDARDS

The way we brew and serve our coffee is rooted in historical practice and scientific inquiry. One of the cornerstones in our brew research (ever used and refined) emerged in the 1950's by a study from the National Coffee Association commissioned by the Massachusetts Institute of Technology. Professor Earl E. Lockhart conducted a series of studies to determine how best to define “coffee quality” where participants in the study preferred coffee that was brewed:

At a concentration (strength) of 1.15-1.45%.

With an extraction level (yield) of 18-22%.

I'll explain more about the distinctions of strength and extraction soon. Below is the SCA Coffee Brewing Control Chart used to visualize how we measure the amount of coffee and water used in a brew in pursuit of that center zone of perfect extraction referred to as a "Golden Cup".

The SCA Coffee Brewing Control Chart

Understanding the SCA Brewing Control Chart

Original research by EE Lockhart and the Coffee Brewing Institute has been refined with global preferences by the SCAE, SCAA and now SCA. In the center section highlighted above we can read that in general people prefer coffee with a STRENGTH (concentration) of 1.15-1.45% at an EXTRACTION (yield) of 18-22%.

From the SCA Coffee Brewing Control Chart we can see several measures and metrics at work. Starting at 12 o'clock (top center) you can follow a set of numbers clockwise around the right side of this chart. Those numbers form the basis of our coffee-to-water ratio.

Coffee-to-Water Ratio: 1:12 - 1:13 - 1:14...

As the name implies this is how much coffee we start with before applying a set amount of water. This is the first step in determining if we have brewed a Golden Cup. There are some ratios which are hard or unwise to use when seeking to brew (those too high and those too low) in the SCA Ideal Zone.

You should understand that a 1:20 ratio is weaker than a 1:15 brew ratio. 1 part coffee to 20 parts water is less strong than 1 part coffee to 15 parts water. 1 = 1 but 20 > 15. More on ratios in a coming lecture. Right now, it's important to align the language with strength concentration.

Strength = Coffee Concentration: 1.15-1.20-1.25%...

These measures appear on the left vertical axis. After a coffee is brewed the strength of dissolved soluble material in the solution can be measured. This is done with a TDS (total dissolved solids) tool or a refractometer which measures light waves bouncing through a liquid. It is also a measure that your tongue can increasingly be trained to recognize as "too strong" ... "balanced" ... "too weak". More on Strength in a coming lecture.

Extraction = Soluble Yield: 18-19-20%...

These measures appear on the bottom horizontal axis. With both the brew ratio and the brew strength, we can trace to find the intersection of these two measures. For example if a 1:18 brew ratio was used and the resulting strength was 1.20%, then as we trace a line from those measure points we find that they intersect at a 20% extraction level.

Try finding the 1:18 ratio @ 1.20 strength to intersect with 20% extraction now. Extraction detection can also be trained in part, but it can be even more challenging to taste accurately than strength. There are several coffee apps with software to calculate these measures based upon the same logic as the chart above. More to come soon on extraction in a coming lecture.

The 7 Essential Elements of Brewing

Within this coffee brewing framework here we have seven elements which are in our control to accurately brew or adjust as needed to improve the coffee beverage. These seven should be understood completely and committed to memory for your skills and for your written exam.

1. Coffee-to-Water Ratio 

- Achieving an optimal brew balance starts here. Adding the appropriate amount of coffee to the planned amount of water is generally in your control as the brew master. Brewing slightly stronger or slightly weaker may be chosen for the enjoyment of your personal taste.

2. Grind Setting 

- Coffee should always be ground to meet the requirements of the brew device, method and filter. Grinding is NOT a matter of preference as some people believe. In general a finer grind dissolves easier and faster than a coarse grind - thus the grind follows brewing device requirements which help determine time and turbulence variables.

3. Brewing Time 

- Brew time is also a function of the brewing device and method chosen. General relationships are at play where a finely ground coffee requires less time than a coarse ground coffee. More time = more extraction. Be careful if you are in control of time (e.g. French Press) that you don't forget or get lazy with your timing. Too much time will cause over extraction.

4. Water Temperature 

- In general most coffee should be brewed between 90°-96°C / 190°-205°F. When you increase the temperature of water, you increase the rate of extraction. Hotter water dissolves more coffee and faster while colder water pulls less soluble matter more slowly. Consistently accurate water temperature is one easy measure for consistently great tasting coffee.

5. Brew Turbulence 

- Turbulence is the movement of coffee grounds amid water. This can be self-introduced with stirring or agitation with water flow, or it can occur naturally from movement of gas bubbles and thermal heat exchange in water. Regardless of the manner of movement, increasing turbulence increases extraction speed by creating more opportunity for water and coffee grounds to interact and dissolve.

6. Water Quality 

- At the foundation level you simple need to know that better water gives a better chance for great coffee. As you will learn, brewed coffee is 98-99% water. Thus, good water provides a chance for good coffee. Bad water provides no chance for good coffee. Water quality measures have specific ppm (parts per million) levels for mineral content and should never display odors or chemicals (like chlorine). Brewing water should be free of odor, clear of color and have a pH of 6-8.

7. Filter Media 

- Paper filters should be rinsed before use as they can emit paper/cardboard/woody flavor to the coffee brew. Metal and cloth filters are reusable and should be cleaned properly to remove old coffee oils which can become rancid and bitter. Brewing is impacted by the filter media used, generally in the following manner:

• Paper filters create a clean and clear brew widely accepted by most people.
• Metal filters create a full bodied coffee with more oils present often enjoyed by those who like "bold" coffee.
• Cloth filters are specific to some brewers (like a syphon) and can create a very clean, distinct flavor profile.

IMPORTANT NOTE

Some brewing devices seldom (or never) reach the Golden Cup SCA Ideal Zone. For the following it is challenging or impossible:

• Ibrik/Turkish - a very concentrated beverage brewed with boiling water
• Moka Pot - a concentrated beverage brewed with steam at high temperatures
• Espresso - a super concentrated strength that requires a different standard "zone" measurement

Despite the fact that the brewers above fall outside of the old Golden Cup guidelines, many coffee drinkers (myself included) thoroughly enjoy the strong complex cups of coffee produced in these traditional methods.