Why It's So Important To Store Cold Brew Coffee In An Airtight Container
Over the past few years, cold brew coffee seems to have made its way onto every the menu of every coffee shop in the land, and for good reason: Coffee aficionados love it for its less-bitter flavor profile, its super-high caffeine content, its low acidity, and its versatility, according to Coffee Bear. Although cold brew is often enjoyed iced, it can also be consumed hot, and its name comes not from how it's served, but rather how it's prepared (by steeping a high amount of coarsely ground coffee in cool water, and letting the beans flavor the water over the next 12-24 hours). Since heat never touches the beans, fewer bitter compounds are released into the infusion, and the resulting coffee is smoother and more well-rounded (via MyRecipes).
As noted by MyRecipes, the slow, gentle process of creating cold brew also means that the resulting coffee takes longer to oxidize and degrade — meaning that cold brew is the perfect candidate for making in large batches and storing at home in the refrigerator to enjoy throughout the week. Undiluted cold brew will keep for up to two weeks in the fridge (via Bon Appétit), but you'll want to transfer it to an airtight container before refrigerating.
An airtight container keeps off flavors out of your cold brew
Refrigerators are a pretty amazing kitchen appliance when you stop and think about it, extending the shelf lives of favorite foods ranging from meat to produce to milk and beyond. And because they're so good at what they do, we tend to pack refrigerators with pretty much anything, leading to an interesting mix of, at any given time, opened condiments, juices, cooked food leftovers, and raw fish, for example. Each of these items brings its own odors to the relatively compact space of a refrigerator, as anyone who has opened their fridge door and immediately known that the milk has gone bad can attest to.
And that is why it's so important to transfer cold brew coffee to an airtight container before stashing it in the fridge. As noted by Coffee Improved, all those subtle odors floating around in the fridge can actually permeate your cold brew, lending off flavors you'd probably rather not perceive. Additionally, Page One Coffee writes that an airtight container keeps out the oxygen that's responsible for degrading the coffee over the one to two weeks it's in the fridge, helping it taste fresher and last longer.