DIY: Cold Brew Coffee

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Picture of DIY: Cold Brew Coffee
I've been a Barista in high end coffee for about 4 years now. One of the things you learn early on is that it is distasteful to ever ice espresso. Many go forward never questioning why this is such a bad idea, but I have an inquisitive mind and looked into it further.

It turns out that coffee is high in chlorogenic acid, which, as the coffee cools, forms quinic acid, which has a noteable and overwhelming astringent flavor. So the task is to brew coffee in a way that does not involve heat, and also reduces the apparent acidity. In the 60's the Toddy method became popular and it produces a finished product that is notably less bitter and actually puts forward a deep caramel and chocolaty flavor. It is perfect for a warm day.

I decided to make my own cold brew coffee brewer.
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Step 1: Materials

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-6oz of a well roasted coffee
-one piece of felt (.29 cents at michaels)
-two large coffee filters
-a two-liter bottle

Step 2: Begin

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Cut the bottom off of the two-liter bottle.

Step 3: Stand

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Use a broad glass to act as a stand for the brewer

Step 4: Filter

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Fold a piece of felt

Step 5: Filter insertion

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Roll up the felt and stuff it into the opening of the brewer.

Step 6: Weigh

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Weigh out 6 ounces of a good, quality coffee. Bad coffee will only get you bad cold brew.

Step 7: Grind

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Grind to the coarsest possible setting.

Step 8: Make coffee "tea bags"

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Split the coffee into two large coffee filters.

Step 9: Tie

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Tie them off with thread.

Step 10: Set in your brewer

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Set them in your brewer, fill with a little over 6 cups of good, clean water

Step 11: Brew!

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Brew for 12-24 hours, this batch brewed for 14 hours.

Step 12: Take off the cap!

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Take off the cap and a slow drip should start.


Picture of ALMOST THERE!
So so close
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Hmmm....I absolutely love this! Must try but will do like others and look for filter other than the felt. I also have two bottles of Secret Squirrel from Ohana Brewery that I will drink till I perfect my skills at this method of cold brewing. :-)

alisa11 month ago

I found a pretty good one, that's from Australia too - it has glassware for labs, so if anything breaks I can replace it

MikeB162 months ago

I love how this is so dude style: cut coke bottle, felt, etc.

This other one is so lady style: clean tubs, nice decanter, etc.

tnwhatzit2 years ago
How about cheese cloth instead of the felt?
A little bacteria and mold in my food do not bother me in the least. 

But the chemicals in the felt do worry me. It would be nice to find an inexpensive reusable filter. Cheesecloth seems like it would let grounds through. Perhaps a well-worn/well-washed cloth would work.

I will commence experimentation...
BethB2 mjenkins14 months ago

Try straining through a nut milk bag? I just ran mine through the reusable filter from my coffee maker and all was well. I know several of the nut milk bags are marketed towards cold brewing though.

Just minutes later, I found a tutorial that uses cheese cloth and a microfine strainer:
WurdBendur2 years ago
How long will this keep? Does it get bitter when it's not fresh?

You've probably already hunted down the answer by now, but I've had good luck keeping mine for up to 2 weeks. I generally drink it up relatively fast though. If you're ever worried you're not going to finish drinking it, try freezing them in to ice cubes for a really nice iced coffee.

joombaloomba6 months ago

0.29 cents < 1 cent...

PaulL26 months ago

I tried making it with filters, it was just too fussy and time consuming for me. I am now using a French press and it works just fine with no fuss and bother.

palscher8 months ago

I'm going to try this too. I think glass wool will work as a filter. I will also try cotton wool , and clean wool roving with no lanolin and report back. I love your set up

Nice instructable, thanks :) Gonna try it out ASAP.

c0ndevon1 year ago
what he did is he cut the bottom of the bottle

check the previous step :)
maximzodal1 year ago
Good instructable except for the hobby shop felt. I would be very leery using any felt, or filter, that was not certified food grade. No telling what is in it.
Rhyno_831 year ago
How much cold brew syrup does this end up making?
Rhyno_831 year ago
Can you explain what you have done to the bottom of the bottle before placing it in the end of the remaining bottle?
Amon-1002 years ago
Hi great instructable, i was just wondering can this cold brew concentrate be added to hot water or warm water in the same fashion to produce a regular cup of coffee. I ask because as a student "vitamin C" is extremely important and while there are coffee shops on campus both good and bad and both expensive.

Lucky hot water is cheep / free and while i have experimented with carrying instant grounds is almost always ends up moisture from the atmosphere ruining the grounds, a liquid coffee concentrate would solve these problems.
You'd probably have to make it a bit stronger than this I'd imagine, I found it just the perfect strength for me when mixed 50/50 with milk. And a shot of caramel syrup never went astray)
Witch3212 years ago
Good morning,

i would like to trie your method. I am in germany and here cold coffee is really unkonwn. I want to maeke drinsk of it like starbucks cold coffee shakes.

But I have one question: Could I use other materials for the last - double filter instead of felt? I do not have any felt at home. Could I just use clean cotton instead oft it?

Thank you.
Hi. I used three paper filters together instead of the felt, and had no problems, tasted great. It's also unheard of here in Australia.
harthoppy2 years ago
Do you need to keep this cold ?
I love the idea i may try it this weekend !
(removed by author or community request)
"As dangerous as sun tea?" My family has been drinking sun tea for generations. I also do the "Toddy" cold-brew all the time. Not once in any generation has anyone ever gotten sick from the tea or coffee. This kind of fear mongering is unnecessary on these forums.
I've made coffee in an electric coffemaker and left it for too many days sitting cold and it grew mold. Counter-intuitively, there's enough organics in it for some fuzzy stuff to grow. Keeping it in the refrigerator after brewing seems to prolong the shelf life of brewed coffee. Our family chooses to drink brewed beverages within 48 hours to avoid the unidentified molds. But maybe they are good for us if we're sick!?
Fear Mongering? Try the CDC. This is like the arguments for whole milk. You must really like throwing dice. I prefer to err on the side of caution rather than stories my granny used to tell me.
Actually, the CDC has never said any such thing. There is no information on the CDC website involving Sun Tea, nor is there any information linking the bacteria named in the snopes article (that you linked previously) to Sun Tea or outbreaks of illness.

Unfortunately, this has not stopped some news outlets from conflating CDC information about improper equipment handling and maintenence (specifically, not cleaning out equipment between uses), and information from the Tea Association, a tea industry group, suggesting sun tea not be brewed.

For a better overview of how all of this happened, I recommend this blog:

Of course, if you have a link to information on the CDC website that I did not find, please pass it along - informed makers are always a positive thing.
To all and everyone-I withdraw. I am sorry that I was mis-informed. I was writing off the top of my head w/out due diligence. Mea Culpa.

That being said, I generally brew my tea (black, organic, fair trade) in a perk on the stove, 2 tsp/9cups. I happen to like it that way. In the summer, I will pour it over ice after work, often adding lime juice...and sometimes rum.

Please enjoy your favorites, and be cautious of sanitation.

Thank You all. Even the snarky ones.
Much respect to you, sir!  To be fair, until this very conversation, I took Snopes as Gospel.  I've even had E-Mail chats with Barbara Mikkelson and have a lot of respect for the woman, but it seems she made the same mistake the media did. 

I apologize for the snarkiness.  I'd blame it on the fact that I hadn't had a cigarette in 3 days, but really I can just be a real ass some times.  :/

My favorite mix is 1-2 shots of the coffee concentrate, a half-shot of simple syrup, and a cup of milk.  Way better than a starbucks frozen coffee for pennies!  (Note:  Don't premix this and leave it in the refrigerator for a few days.  I still haven't figured the chemistry behind it, but I swear every time I've done this, it gets a very light "soap" flavor no matter how rinsed the glass containers are.)
Fascinating article, LadyCrymsyn!  I wonder if this was the original CDC memo that started the whole debacle.  It's dated just months before the paper was put out:

Straight from the CDC:

"Finding indicator organisms, such as fecal coliforms, in brewed tea does not mean that the tea is in fact hazardous. Rather, this indicates a failure in food handling or sanitation..."

"Tea is a beverage with little history of disease transmission. At present, no outbreaks of infection have been reported to CDC that were clearly associated with the consumption of tea."
According to the book about the Trans Continental Railroad, the Irish in the east did not bathe and drank whiskey, while the Chinese in the west bathed, drank mostly tea, and ate fresh food with vegetables. The Irish died from diseases, while the Chinese tended to die more from accident in mines and tunnels.

Nothing Like It In the World: The Men Who Built the Transcontinental Railroad 1863-1869 by Stephen Ambrose.
I prefer to err on the side of science and common sense instead of the fears purported by a government branch with an agenda that is not necessarily in the interest of the people. See my above comment about the CDC and WHO.
Broom Javin0072 years ago
Technically, he's right. It's every bit as dangerous.

Almost as bad as running with blunt-end scissors, or eating a snack less than a half-hour after swimming.
Ditto. The only times I have ever been leery of drinking SunTea was when it had sat in its jar in the fridge waaay too long (it happens; we were SunT'd out for awhile) or was made with herbal ingredients that could cause an allergic reaction for me. If I make it myself, no problem.
Cold-brew coffee doesn't last in my house long enough to ever go bad, haha!
"Sun tea" is not dangerous. If it is, then kindly supply data on how many people fall sick from it yearly.

Neither tea nor coffee are good growing media for most pathogens, so they do not quickly become "contaminated".
Yep, Snopes has certainly jumped on the CDC fear mongering bandwagon. Why don't you pull up some research on the very bacteria they're talking about? (alcaligenes viscolactis) Sure, it's "often found in water" because it's often used in wastewater treatment plants. It's actually a GOOD bacteria (breaks down arsenic into a less dangerous form) that has ONLY been found (asymptomatically) in the lungs of cystic fibrosis patients.

Then there's that inconvenient fact that even though it doesn't actually DO anything to the average human on consumption, it's still killed by the UV rays of the sun while the tea is steeping.

So yeah. Let the fear mongering continue.

The CDC and WHO come out with their yearly scare to justify their paycheck. That's the long and the short of it. Remember Swine Flu? Or should I just say H1N1? Oh, that's right, that's the REGULAR FLU. In fact, by percentage, "Swine Flu" killed fewer people than regular flu. (And my fiancee and I caught it. Yes, we were tested and tested positive. It was more mild than a regular yearly flu.) How about the mono "epidemics?" Bird flu? West Nile Virus? Go ahead and pick your scare for the year. But then do a little research on it and you'll find that not a single one of these diseases is any more deadly than the common flu. Every now and then they hit on something that's a legit danger, such as Mad Cow Disease. But after crying wolf so often, it's hard to believe them when they do.

My background: I did medical research at Naval Medical Research Unit #3 (NAMRU-3) in Cairo Egypt as a 91T in the U.S. Army. Currently researching for a book about biochemistry in diets.
and kudos go to javin007 for both an opinion and the (exemplary) ability to back it up. And we appreciate your service!
Broom kretzlord2 years ago
Oh, and as a side note, I'm pretty sure Broom asked for data on HOW MANY PEOPLE get sick from sun tea. Your link has a distinct lack of this information. In fact, I couldn't find a single case where anyone had ANY proof that ANYONE has EVER gotten sick. Just a lot of the fear-mongering experts saying, "Well YOU say you've never gotten sick from sun tea. We say you HAVE but you just didn't know it."

REALLY?! This is what passes for SCIENCE these days?
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