Brewing Coffee (a Framework)
What Happens When You Brew Coffee...
When you brew coffee, hot water acts as a solvent, washing the soluble solids out of the coffee grinds and into the brew. If you dissolve table salt in water, you have a soluble solid. Soluble solids are bonded with the water molecules, and will not separate over time. Brew methods that use paper filters have only the soluble solids in the cup. Some brew methods allow insoluble solids to enter the brew, like French Press, espresso or Turkish coffee. Insoluble solids will settle out of the brew over time if you don't disturb the liquid. Hence your mug of French Press coffee might taste gritty nearing the end, and there will be muddy residue in the bottom of the cup. Suspended solids add a sense of body to the cup, but can also add bitter tastes..
The 5 main factors that affect your brew:
- Coffee-to-water ratio. Most people find that when 20% of soluble solids are extracted from the coffee grounds, the brew has the best flavors. Too much extraction (too fine grind, too long brew time, too hot water, too much ground coffee) and the brew tastes bitter. On the other hand, under-extraction results in a thin, weak, sour cup. Simply using more coffee grounds doesn’t correct under-extraction. It is a good idea to weigh your coffee or use an SCAA coffee scoop or a measuring device that you know will hold 10 grams of coffee. It is also a good idea, at least initially, to weigh or measure your water as well.
- Coffee particle size. A finer grind means more surface area of the bean is exposed to the water. For a brew method that uses a longer dwell time such as French Press, a coarser grind is necessary. An even grind of any size is ideal, follow the directions on your grinder, it may take some experimentation to find the best grind for your brew method here is an illustration (photo of different grinds)
- The Water Temperature. The ideal water temperature is 195-205 f, since water is a better solvent at near-boiling temperature. This is why it is always better to brew a full batch on an auto-drip machine, since they are built to get a full batch of water up to the proper temperature.
- Contact time. How long the water and coffee are in contact with each other. See our brewing instructions below.
- Agitation. Stirring the coffee-water infusion increases the extraction rate of soluble solids. Keep in mind that pouring water over the grounds causes agitation. In immersion brew methods it is important to agitate (stir) the brew again during the dwell time.
- Heat Retention. Don’t let coffee sit on a hot plate or in a French Press transfer to a thermal carafe to avoid overcooking and over-extraction.
Other factors that have a major impact are:
- The quality of the water. Bad tasting water makes for bad tasting coffee. Also, do not use distilled water. You need some mineral content to properly extract the good stuff from your coffee. The absence of some minerals can lead to very sharp and bitter tastes.
- The quality of the coffee you are using, obviously, and also the roast level. Speaking in broad terms, some roast levels perform better in different brew methods. Lighter roasts can taste aggressively bright in immersion brewers and some pour over methods don't really showcase the caramelized sweetness in darker roasts. Of course, brew ratios can address some of these issues.
-The cleanliness of the brewing equipment. Old sediments easily make for rancid flavors in the cup. A good rule of thumb is: if you smell an odor from your equipment, clean it. If you can’t remember the last time you cleaned your brewer, clean it.
The ideal brewing practice is:
- Grind immediately before you brew.
- Adjust grind to brewing method and use a grinder that produces a consistent grind.
- Use fresh, clean water. If your water does not taste good, your coffee won’t either.
- Pre-rinse your paper filter to remove any loose paper fibers that can end up in your brew and make your coffee taste papery.
- Heat retention is also an issue in many manual-brewing devices, Pre-heat your filtercones and presses.
- Don’t let it sit. Coffee is only fresh for about 10 minutes. Try to make the right amount of coffee so you are drinking fresh brewed coffee more often.
Here are some ideal coffee/water/time ratios for different brewing methods: