How to Make Cold Brew in a Mason Jar: A Flavourful Guide

Joshua Allerton
February 21, 2024

There's nothing quite like starting your day with a refreshing cold brew. It's smooth, it's rich, and when I discovered I could make it at home in a mason jar, it was a game-changer. I'm here to share that revelation with you. Making cold brew at home not only saves you a trip to the coffee shop but also gives you control over the strength and flavour of your coffee.

Choosing the Right Coffee Beans

When I started my journey into making cold brew at home, I quickly realised the importance of selecting the right coffee beans. It's not just about grabbing any bag off the shelf; it's about finding beans that suit your taste and enhance the cold brew experience.

Understand the Flavor Profile

First things first, medium to dark roast beans are usually recommended for cold brew. They have a milder acidity compared to light roasts and offer a smooth, chocolatey flavor that blends beautifully with the cold brewing method. I've experimented with various roasts and found that beans with a rich, full-bodied profile tend to produce the most satisfying cup.

Single-Origin vs. Blend

Here's where personal preference plays a big role. Single-origin beans, from one specific location or farm, provide a unique taste characteristic of their region. They're fantastic if you're after a distinct flavor that stands out. On the other hand, blends can offer a more balanced taste, combining the best characteristics of beans from different regions. I tend to lean towards blends for my cold brew as they usually offer a well-rounded flavor that's hard to beat.

Organic and Fair Trade

For those of us conscious about the source of our coffee, opting for organic and fair trade beans is a great choice. Not only do they ensure that farmers receive a fair wage, but they also mean you're getting beans free from synthetic pesticides and fertilizers. I make it a point to look for these labels when shopping, as it adds an extra layer of satisfaction to my cold brew knowing it's made ethically.

Finding the perfect coffee beans for your cold brew might require a bit of trial and error. Don't be afraid to experiment with different roasts, origins, and blends until you find your perfect match. Remember, the best coffee is the one that suits your taste the best.

Grinding the Coffee to the Correct Coarseness

After selecting the perfect beans for your cold brew, the next crucial step is grinding them to the ideal coarseness. I’ve learned through trial and error that the grind size directly impacts the extraction process and, ultimately, the taste of your cold brew. Let me guide you on how to get it just right.

Why Coarseness Matters

In cold brewing, coarse grind is king. A coarse grind allows for a slow and even extraction—essential for achieving that smooth, rich flavour we all love in a cold brew. Too fine, and you risk a bitter, over-extracted brew. Remember, we're not making espresso here; we're crafting a chilled caffeinated masterpiece.

Achieving the Perfect Grind

To grind your coffee beans to the perfect coarseness for cold brew in a mason jar, follow these simple steps:

  1. Measure Your Coffee: I usually go with a 1:8 coffee-to-water ratio. For a standard mason jar, that’s about 1 cup of beans.
  2. Choose Your Grinder: A burr grinder is ideal as it allows for more consistent grind sizes. If you don’t have one, a blade grinder works too—just pulse gently to avoid over-grinding.
  3. Select the Coarse Setting: On your grinder, select the coarse grind setting. Think breadcrumb texture—not too fine, not too chunky.
  4. Grind Your Beans: Pulse or grind your beans until they reach the desired coarseness. Remember to pulse if using a blade grinder.
  5. Check the Grind: Before moving on, ensure your grounds resemble coarse sea salt. This texture is perfect for allowing water to circulate and extract all the flavorful oils and compounds.

Achieving the perfect grind might take a bit of practice, but once you get it down, you’ll elevate your cold brew to professional levels. Plus, there's something incredibly satisfying about grinding your own coffee—it connects you to the brewing process in a unique way, making that first sip even more rewarding.

Brewing Process in the Mason Jar

After finding the perfect coarseness for your coffee beans, I've got to say, the magic truly begins when you start brewing in a mason jar. There's something genuinely fulfilling about this method, and I'm here to guide you through every step.

First off, you’ll need a clean mason jar. Size can vary, but I find that a 1-litre jar is just about perfect for a substantial batch that'll last a few days. Make sure you've got your coarsely ground coffee ready to go, and let's dive into the simple yet delightful process.

Here's a quick breakdown for a hassle-free brewing experience:

  1. Measure Your Coffee and Water: For a bold and robust cold brew, I usually stick to a 1:8 coffee to water ratio. For a 1-litre jar, that's about 125 grams of coffee to 1 litre of water.
  2. Add Coffee to Jar: Pour your ground coffee into the mason jar.
  3. Pour Water: Slowly add cold or room temperature water to the jar, making sure to fully saturate the grounds. I prefer using filtered water for the best taste.
  4. Stir Gently: With a long spoon, give it a gentle but thorough stir to ensure all the grounds are wet.
  5. Seal and Refrigerate: Put the lid on the jar and tighten it. Then, place the jar in the fridge. I recommend letting it brew for about 12 to 18 hours. This slow extraction process is crucial for developing the rich and smooth flavour profile that cold brew is known for.
  6. Strain: After your brew has steeped, you’ll need to strain it to remove the grounds. I usually pour it through a fine mesh sieve or cheesecloth into another container. For an extra-smooth drink, you might want to strain it twice.

Throughout this process, you'll notice the coffee aroma gradually changing. It’s quite fascinating. Once strained, your cold brew concentrate is ready. It can be stored in the fridge for up to two weeks, though I doubt it'll last that long once you taste it.

Straining and Storing Your Cold Brew

After patiently waiting for 12 to 18 hours, it's finally time to turn that steeped concoction into the smooth, flavourful cold brew coffee we're craving. I like to think of this part as unveiling the magic. Let's dive into how to strain your brew properly and store it for that perfect cup anytime.

Straining Made Simple

Straining is crucial. If done hastily, you might end up with a gritty cup. Here's how I ensure a clean, clear drink:

  1. Prepare Your Tools: Grab a fine-mesh sieve and line it with a cheesecloth or coffee filter. I've found that a nut milk bag also works wonders.
  2. Position Over a Container: Place the sieve over a large bowl or pitcher, ensuring it's stable.
  3. Pour Your Brew: Gently pour the coffee from the mason jar through the sieve. This might take a bit, especially if you're using a coffee filter.
  4. Discard the Grounds: The soaked coffee grounds can go straight into your compost or garden. Your plants will thank you!

Storing for Longevity

Once strained, your cold brew concentrate needs a home that keeps it fresh and ready. Here's what I do:

  • Transfer to an Airtight Container: Pour the strained cold brew into a clean mason jar or any airtight container. This step helps preserve the flavour and freshness.
  • Refrigerate: Cold brew loves the cold. Store it in the fridge immediately.

Remember, cold brew concentrate is potent. When you're ready to enjoy, dilute it to taste with water, milk, or a dairy-free alternative. Ice, sweeteners, and flavourings are all optional but can elevate your coffee experience.

I've been making my cold brew this way for years, tweaking little things here and there. The result is always a refreshing, smooth, and richly flavoured beverage. Whether I'm kicking off my morning or need an afternoon pick-me-up, it's my go-to. So give it a try, and see just how easy and enjoyable homemade cold brew can be.

Experimenting with Flavours and Additions

After mastering the basic cold brew technique in a mason jar, I quickly found myself eager to spice things up a bit. Let's be honest, the rich, smooth taste of cold brew is fantastic on its own, but there's a whole world of flavours and additions out there waiting to elevate your coffee experience. Here's how I've been adding a bit of pizzazz to my cold brew concoctions.

First off, let’s talk simple syrups. They're incredibly easy to make and can infuse your cold brew with a myriad of flavours. Here are a couple of my go-to recipes:

  • Vanilla Syrup

  • 1 cup water
  • 1 cup sugar
  • 1 vanilla bean, split and seeds scraped
  • 1 cup water
  • 1 cup sugar
  • 4 cinnamon sticks

For both, simply combine the ingredients in a saucepan, bring to a boil, then simmer until the sugar dissolves. Cool, strain, and voila! You've got yourself a homemade syrup that can be stored in the fridge for up to a month.

Next up, spices and herbs. Adding these directly to your brew can subtly change the profile of your coffee. Think a dash of cinnamon or a sprig of fresh mint. It’s all about personal preference. Start with small amounts; you can always add more to taste.

Lastly, don’t overlook the impact of milks and creamers. While black cold brew is delicious, adding different types of milk or dairy-free alternatives can transform your drink. Almond milk adds a nutty flavour, whilst oat milk is creamy and slightly sweet, making it a fantastic complement to the robust nature of cold brew.

Remember, the key to perfecting your cold brew is experimentation. Don't be afraid to try new things and adjust according to your taste. There’s no right or wrong here, only discovery and enjoyment. So go ahead, mix and match flavours and additions to find your perfect cold brew concoction.


Crafting the perfect cold brew in a mason jar is an adventure that's as rewarding as it is delicious. I've shared my insights on playing with flavours—from homemade syrups to unique milk alternatives—to help you elevate your coffee game. Remember, the secret lies in the willingness to experiment. Whether it's a dash of cinnamon or a splash of oat milk, each addition is a step towards your ideal brew. So, don't hesitate to mix and match until you find that perfect combination. Happy brewing!

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