How to make cold brew

I normally pay \$5-6 for cold brew out at a coffee shop. That’s about \$0.45/oz of coffee! I’m all for supporting local business, but I am also a local business and need to support myself, so here’s how to do it at home. The secrets won’t surprise you!

The Process

  1. Gather ingredients and tools. The total cost for the tools should be less than $40. Two big jars and a metal filter. A blade grinder if you don’t have a blender that works.

    1. Coffee Beans (ingredient): Ideally freshly roasted. Whole is ideal if you have a grinder, otherwise ground is good too.
    2. Water (ingredient): Fresh drinking water, no salt.
    3. Brewing Jars (tool): Two 64 fl.oz mason jars.
    4. Metal Coffee Filter (tool): Stainless steel mesh filter, hard to find locally, I’ve purchased from Amazon.
    5. Cheese Cloth (tool): Optional. If you want to filter out all of the silty coffee residue (totally sensible), just use a cheese cloth, they’re like two bucks, reusable, and washable. Don’t waste money/resources on paper coffee filters. This method is simple if you have two jars: a brewing jar, and a serving jar.
    6. Rubber Band (tool): Optional. To secure the cheese cloth to the jar for easier filtering.

  2. Grind coffee beans. (Skip this step if you bought pre-ground). Use a blade grinder, burr grinder, or whatever they have at your local grocery store where you buy your beans. Go for the coarsest ground you can get. Could probably just use a knife and chop up the beans by hand.

  3. Add grounds to the coarse filter: Add 5.33 oz (1/3 of a 1 lb bag) of grounds to the coarse filter. If you don’t have the coarse filter, add the grounds directly into the jar, you will filter them out later. I use 1/3 of the bag and dilute the coffee after, you can always add 4 oz if you want weaker cold-brew, or 8 oz if you want it stronger. Pick your own number, you will have to test it out a few times to determine what you like.

  4. Place ground and filter into jar: Yeah, it should fit in quite nicely if both jar and filter are wide-mouth.

  5. Slowly fill jar with water: Pour the water directly onto the grounds, making sure to soak the grounds thoroughly. Don’t overflow the jar, so you may need to trickle water into the jar. Typically, this step takes the longest.

  6. Brew for 8-24 hours. In a pinch, after about 8 hours it starts to taste like coffee. I typically brew overnight (8pm - 8am, roughly 12 hours), or for a full 24 hours. Past 24 hours, it starts to taste weird, dunno why. Shocking fact, the warmer the air temperature is for the “cold brew” process, the faster it will brew. Leave it in the fridge (roughly 37 F), and it will brew slower than leaving it at room temp (70 F). I’ll typically brew it the morning before, leave it on the counter all day, then refrigerate it at night so it’s cold when I drink it in the morning.

  7. Filter cold-brew from grounds. You can drink it with the grounds if you like, but I do not, so I remove the coarse filter (with grounds) from the brewed coffee. Next, I bring out the second jar, and place the cheese cloth over the second jar forming a nice valley (opposite of a mountain) to act as a filter for the coffee. I attach the cheese cloth using a rubber band so I don’t have to hold it, then I slowly pour my cold-brew though the cheese cloth from the first jar into the second jar. This way, I filter out any fine particles still left in the coffee, resulting in a much cleaner taste. Some even filter the cold-brew again through an even finer coffee filter, but this is far enough for me.

References

  1. I looked up some papers referencing the taste variation in coffee brewing temperatures, and this one(1.1) discussed decreased acidity, lower concentration of browned compounds, and fewer total dissolved solids in cold-brew coffee. This paper(1.2) stated “the hot brew coffees were found to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that of their cold brew counterparts.” Shoutout to Rao and Fuller for actually studying cold brew coffee and getting published in Nature, one of the top journals in the world. Badass!
  2. Interestingly, this paper(2.1) argued that a consistent hot-brew temperature wasn’t very important, going against the conventional wisdom of coffee brewing certifiers. I love how science sometimes agrees with longstanding conventional wisdom, and sometimes blows it out of the (hot) water.

Papers