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When I first started making cold brew coffee about 7 years ago, the advice was to brew overnight at room temperature. Once strained, any leftover coffee could be stored up to 2 weeks in the fridge.
That was then, this is now. With the popularity of cold brew in recent years, we now have better information and research to call upon.
I now recommend brewing in the fridge and storing your cold brew for no more than a few days. This will ensure your coffee tastes its best and reduces the risk of microbial growth.
We’ll look at three main things:
Can I make cold brew coffee at room temperature?
Will something terrible happen if you brew at room temperature? No, not likely. But, one of the reasons people like cold brew coffee is because of its lower acidity. Cold brew coffee’s pH tends to be between 5-6. According to Kwok et al. (2020) this is not acidic enough to suppress microbial growth.
We also now know that most of the good stuff is extracted in the first several hours, so if you want to brew at room temperature, overnight should be fine. For most people this means 8-14 hours. This is assuming a typical room temperature of about 70 degrees F/21 degrees C.
If you have a warm home, you will want to brew for less time or choose to brew in the fridge.
You should always use clean equipment to make your cold brew, but if you are brewing at room temperature it becomes extra important to start the process as germ free as possible. Wash your equipment in the dishwasher, or if by hand use hot, soapy water.
To make cold brew coffee at room temperature, simply mix medium to coarsely ground coffee and room temperature water in a jar or pitcher.
The ratio of coffee to water can vary depending on your preference, but a good starting point is 1 cup of coffee to 3 cups of water. Stir the mixture well and let it sit at room temperature for 8-14 hours.
Temperature is a factor in coffee extraction, influencing both brew time and flavor. Cold brew coffee brewed in the fridge may have a slightly more acidic taste and a lighter body than cold brew coffee brewed at room temperature. Once stored in the fridge, pH will gradually drop and your coffee will become a touch more acidic.
What about commercial cold brew coffee?
Many ready to drink cold brew products are sold at room temperature but they are often treated with high pressure processing, or pasteurization to kill off any harmful bacteria.
These ready to drink coffees and concentrates are shelf stable until the date printed on the packaging as long as they are unopened.
Once the bottle is opened, any leftover cold brew should be refrigerated. Refrigeration will help maintain the taste and quality of the cold brew, ensuring that it stays fresh for longer.
Why should cold brew be refrigerated?
Left at room temperature, cold brew can quickly become stale and rancid. This is because coffee oils can become rancid when exposed to oxygen and light.
Refrigeration slows down the oxidation process and helps to preserve the freshness of the coffee. That said, cold brew has fewer oils than hot brewed and so it doesn’t go rancid as quickly.
In addition to freshness, refrigeration also helps to prevent growth of molds, yeasts, and bacteria. This can be dangerous to your health, not to mention ruin the taste of your coffee. When left at room temperature, water based products can be a breeding ground for microbes, whereas refrigeration slows down growth.
If you’re making large batches of cold brew, it’s important to store it properly. You can store cold brew in the fridge for up to a week, but after just 2-3 days it may start to lose its freshness and flavor.
If you want to make a large batch of cold brew that will last longer, you can freeze it in ice cube trays. These cubes are perfect for cooling your cold brew without diluting the flavor.
Some tips for storing cold brew coffee
When it comes to storing cold brew, there are a few things to consider to ensure that your coffee stays fresh and tasty.
Choosing the right container is crucial when it comes to storing cold brew. An airtight container helps to prevent oxidation, which can cause the coffee oils to go rancid and affect the flavor profile.
Glass containers, such as mason jars or pitchers, are ideal for storing cold brew, as they do not react with the coffee and are easy to clean. However, plastic containers can also work, as long as they are BPA-free and airtight.
Choosing dishwasher safe storage containers will not only make cleanup easy, but the higher temperatures of the dishwasher help ensure your equipment is sanitary before each use.
If you have made it this far, you already know that storing your coffee in the fridge is essential for any leftovers.
If you are using sealed containers (like a mason jar or pitcher with a lid) you should have good flavor at least until the next days.
Flavors will gradually deteriorate with each passing day. Any unused cold brew should be discarded after a week for safety.
Room Temperature Storage
If you do not have space in your refrigerator, you can brew your cold brew at room temperature and drink it right away. From the time you start brewing, you should aim to consume it within a day. Make only enough for one day at a time.
You can also store your cold brew in an insulated bottle for the day. Insulated containers can keep your coffee cold for 24 hours or more.
Freezing Cold Brew
You can freeze leftover cold brew. I recommend freezing cubes in an ice cube tray, and then once frozen, removing the cubes form the tray and storing in an airtight container. This will keep your cubes fresh and prevent them from picking up odors from your freezer.