Ode to the Office Coffee
Daily I invariably witness the nascent behavior of a co-worker brewing a fresh pot of coffee, filling their mug with ice and stirring up something that resembles the Gulf of Mexico after the Deepwater Horizon disaster and has an aftertaste similar to a week old bottle of Chianti. Even more disconcerting is taking the leftovers from the morning pot and sticking it in the fridge for a beverage the next day. Why is that oil slick there and why is the roof of your mouth dried out? Can you get rid of those issues, free to enjoy an iced coffee without the rainbow hue OR the $5.00+ price tag from the local coffee shop?
If you’re not a chemistry savvy person, you’re going to love this. If you love the scientific method, acquiring knowledge through trial and investigating phenomena, this is for you. If you have an affinity for both wine and coffee, you have arrived.
Red wine gets its variety of colors from light ruby to dark purple from the contact differing grape varietals’ juices have with the skins of the fruit. The winemaker can change the depth of the color by lengthening this contact time in a process called maceration. This process of softening solids results in many compounds being released into the juice, including tannin. Tannin is a general term for a group of acids that occur naturally in most plants. In wine they produce that feeling in the roof of your mouth that’s dry, almost rough on your tongue. Proanthrocyanidins are the tannins in wine and chlorogenic acids are found in coffee.
Raw green coffee contains tannins at lower concentrations than red wine. As a reference point, ground cinnamon would be at the top of the range for tannin. The higher the tannin levels, the more astringent your coffee will taste. How then does tannin enter your coffee and is there a way to reduce the amount that gets there?
Chlorogenic acid (C16H18O9), the tannin found in raw, un-roasted coffee has a melting point of 408 degrees Fahrenheit (any coffee roasted past “very light” will reach this temperature). A process called the Maillard Reaction (it’s the same process that happens when you sear a steak or roast a marshmallow) changes the sugar and acids structures in the coffee very rapidly between the temperatures of 284 and 329 degrees Fahrenheit.
Once coffee has cooled after roasting one of the phenols that results is called Guaiacol. It melts at a mere 82 degrees Fahrenheit. This means that Guaiacol is present in the water making up your coffee at any temperature modestly above room temperature.
The Best Iced Coffee You’ve Ever Had
We want to acquire all of the delicious benefits of roasted coffee, including those sweet notes from the Maillard Reaction, without all of the tannins we can brew our coffee cooler than 82 degrees Fahrenheit. Remember you will not remove all of the acids from your coffee, but this method can significantly reduce them, allowing for a lower acid content coffee. That’s good news for all of you that have stopped drinking coffee at one time or another because it upset your stomach.
Hot water facilitates the extraction of all the compounds in your ground coffee faster than cold water. The size of the coffee grounds changes the available extracting surface area. So if we can increase brew time and decrease grind size, we can find a happy medium of time where maximize the extraction of flavor and we won’t encounter the dangers of bacterial growth.
The result is a coffee concentrate that is low in tannin (which makes it taste sweeter) and will be full strength instead of watered down after you add ice.
Buying the supplies listed here will give you years of cold brew bliss. Below is a recipe for making 1 gallon of cold brew coffee (128 ounces).
*Should you desire to start with a small amount in a French press to dial in your preference in strength, be sure to grind to French Press size for the testing method, not the smaller grind size listed below.
2 gallon food safe container with a tight fitting lid
Commercial sized basket or coffee filters, found at restaurant supply stores or a reusable hemp filter
Food safe rubber band or butcher string
Filtered water (the better your water the better your coffee)
We recommend starting with 12 ounces of coffee per gallon and then adjusting to your preferences.
Place 1 gallon + 1 pint of water into your container.
Sprinkle 1/16 teaspoon of Kosher salt into the water. It acts as a mild preservative and flavor enhancer. If you are watching your sodium intake, you can skip the salt.
Grind 12 oz of coffee at a setting between drip and pour over (espresso or Turkish is too fine and may precipitate through the paper filter).
Pour the grinds into the filter and secure it with butcher string or a food safe rubber band (like the ones that come around broccoli stems or asparagus bunches). You can pour the grounds directly into the water, but filtering and clean up becomes a time consuming task.
Place gently into the water with the closure up and tightly secure the lid.
Leave on the counter top for 24 hours out of direct sunlight and away from any heat sources. If you decide to steep the coffee for longer, place it in the fridge. This will slow the extraction process down significantly, but anything more than 36 hours at room temperature and you risk bacterial growth.
Remove the filter with a colander, being careful not to tear the filter (this makes clean up a breeze). If you can suspend the colander on the rim of the container, you can let the trapped water drain back into the cold brew, increasing your concentration. After a few minutes set the colander on the lid to catch any additional runoff.
Funnel the cold brew into a container of your choice. We like gallon water jugs from the grocery store because they close tightly and fit anywhere the milk gallons fit.
Lance Odvody is the primary owner of Bethesda Roasting Company. He’s also a Certified Sommelier and has a love for all fine beverages and 20 years of restaurant experience. He resides in Durham, North Carolina with his wife Ashley and their three sons.