It’s true that coffee preparation has become a more specialized skill over the last 20 years. Through technology, education and coffee quality, all of these aspects have gone hand-in-hand in the development of what coffees we prefer to prepare today and how we choose to prepare them. By cultural expectation, tradition and even necessity, coffee is brewed all across the world in many different ways. With a common coffee language its possible to communicate ideas and recipes more clearly, and advancement in the craft has seen a boom through such dialogue.
Ultimately, a big part of understanding and enjoying coffee is the shared experience. Because we love to talk about coffee, we figured the best place to start the conversation would be to share some common terms used in the specialty coffee industry in an effort to better communicate with you about the decisions we’ve made with your brews. These terms have come about through off-hand & formal conversation and have stuck to become standardized nomenclature for baristas, coffee professionals and home-brewers alike.
Common Coffee Brewing Terms
Brew ratio – This refers to the weight of coffee used in relation to the weight of water used to brew coffee. Brew ratios can vary from coffee to coffee, and we’ve seen them vary greatly depending upon degrees of roast. A common brew ratio for filter coffee is somewhere around 16 to 1. That would mean you’d use 16 grams of water to 1 gram of coffee (this works for ounces too!). If you’re ever wondering how much water to use with your last 30 grams of coffee in your bag, just multiply your coffee weight by 16!
30 grams of coffee x 16 = 480 grams of water
*For espresso, a ratio of 2:1 is desirable. 2 grams of water to 1 gram of coffee. Potent!
Brew Time – This refers to the amount of time from the initial introduction of water to the ground coffee, until the final second of dripping into the brewing receptacle. As it turns out, brew time doesn’t greatly affect extraction percentages of coffee, though can greatly affect flavor and the mouth feel. Brew time and its influence has come under great scrutiny as of late. We’re curious to experiment with this further.
Dose – The term “dose” is used to describe the amount of coffee grinds used in the recipe to brew a particular cup of coffee. The dose is one part of the brew ratio. It’s a fitting name for the amount of coffee one may need to wake up in the morning.
Water Weight – This directly refers to the weight of the prescribed amount of water for a particular brewing recipe. Generally used in describing an aspect of filter brewing, water weight is used in conjunction with dose to make up the brew ratio.
Brew Yield – Generally used in describing the final weight of espresso or filter coffee in the cup at the end of the brewing process. Water that is retained in the coffee bed, plus the brew yield, make up the total water weight.
Pre-Infusion – “Pre-Infusion” refers to the time – and can be used to reference the amount of water – used in the initial phase of the brewing cycle. The Pre-Infusion phase is used to saturate the ground coffee particles and prepare the grinds to be fully extracted. Pre-infusion time is affected by the resting time of the coffee. The more fresh & gaseous the coffee is, the longer it will take for the pre-infusion water to penetrate the grind particles and become ready to extract.
Agitation – This term is generally used to describe one of the controllable variables during the brewing cycle that can affect the flavor of the brew. Agitation can be used vigorously to increase the level of extraction, or lightly to decrease the level of extraction at any phase of the brewing cycle. Agitation can be administered by pouring style and paddle stirring for manual brewing, or pulses of water in the auto-brewer.
Slurry – This term is used to describe the mass of water and coffee in the filter during the brewing cycle’s extraction phase. Temperature & level of the slurry are variables that are referenced when addressing flavor components, extraction time, and extraction % of a brew.
Extraction – Extraction, literally defined, is “the act or process of getting something by pulling it out.” In the craft of coffee brewing, organic acids, esters, and soluble & insoluble solids are the solute and water is the solvent used to extract the organic compounds to create a brew.
Extraction Percentage – This is a serious one. Extraction percentage refers to the amount of coffee you’ve taken out of the coffee grinds, and dissolved into the brew. Generally, coffee grinds are able to give up 30% of their mass when being brewed. The sweet spot that is generally agreed upon by coffee professionals is somewhere between a 19 & 23 percent extraction.
If a coffee is brewed over the 24% mark, you’ll notice flavors of excessive lingering bitterness, sensations of drying and a hollow sensation in the middle of your tongue where a tasty flavor should be. This is called over-extraction.
If a coffee is brewed under the 19% mark, you’ll definitely experience unpleasant tartness, astringency, and even a sharp pain in your throat when swallowed. This is called under-extraction and it sucks. This chart shows how we go about finding our ideal extraction %.
The reference line through the chart can vary in degree of angle based on your brew ratio. Though traditional brew charts top out at 22% extraction as “perfect”, it is through more specialized grinders creating a more even grind particle size that we are able to achieve higher extraction percentages while staying in tasty town.
TDS – Total Dissolved Solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. To determine the TDS of a coffee, we employ the use of a refractometer. This reading can be used to determine the extraction percentage of the coffee grinds in a particular brew.
Refractometer – A refractometer is a digital instrument used to measure a solution’s composition and total dissolved solids (TDS). With this tool, we can quickly take a reading of a solution (or coffee), quantify it on the refractometry index (“RI”), and calculate the percentage of the coffee seed which was extracted..
Basically, you can put a drop of coffee on a laser “eye”, like a cd reader, and it “sees” how much light is passing through the coffee from the outside to the eye. This actually gives us a Strength % of material in the solution. Readings for espresso will be somewhere – generally – between 8% and 11%. This means the actual espresso beverage is composed of, say, 10% coffee and 90% water! Filter coffee readings are generally around 1.4%… so 98.6% water. The relatively diluted brew can produce a much more nuanced cup with higher flavor clarity.
(Testing different recipes of Cold Brew using a Refractometer & Brew Control chart)
Hopefully these terms shed light on some of the things that you’ve heard us talking about in the past, as well as open some avenues of communication when you visit the shop! Let us know what you prefer… a 2:1 espresso, a 1.8:1 espresso, a 15:1 filter brew, whatever! If there is anyway we can accommodate your preferences, we would happily take it upon ourselves to make it a reality.
In the meanwhile, if you have any questions about these terms, let us know through the comments section below!