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.

Step 1: Materials

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

Comments

[Rhyno_83]

How much cold brew syrup does this end up making?

[Rhyno_83]

Can you explain what you have done to the bottom of the bottle before placing it in the end of the remaining bottle?

[Amon-100]

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.

[loafers]

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)

[Witch321]

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.

[loafers]

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.

[tnwhatzit]

How about cheese cloth instead of the felt?

[mjenkins1]

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...

[mjenkins1]

Just minutes later, I found a tutorial that uses cheese cloth and a microfine strainer: http://thepioneerwoman.com/cooking/2011/06/perfect-iced-coffee/

[WurdBendur]

How long will this keep? Does it get bitter when it's not fresh?

[harthoppy]

Do you need to keep this cold ?
I love the idea i may try it this weekend !

[LadyCrymsyn]

Could anyone clarify for me: is there a particular roast that this brewing method works best with? When drinking regular drip coffee, I prefer a lighter roast (like a breakfast roast or a city roast). But this calls for "6oz of a well roasted coffee", and I'm not sure if that means a coffee that has been roasted skillfully or a coffee that has been roasted until it's well-done. Any help would be appreciated.

[loafers]

I myself have no idea, I just grabbed a pre-ground bag of some good smelling/tasting stuff from a coffee shop nearby (Gloria Jeans) and it worked great. I also recommend replacing the felt filter with a couple of paper filters in a funnel, got a much smoother flavour out and I didn't have to worry about weather the felt had anything in it to be worried about, coffee filters were made for that.

[loafers]

Made this just a couple of weeks ago with a couple of little changes, and loved it!

I use a 270g bag of preground espresso beans, I replaced the felt filtering with a layer of 3 paper filters sitting on a funnel (worked very well that way!) I also did it in just a 2L jug (the sort I usually put orange juice in), rather than mangling a coke bottle. Worked Great!

A half shot of caramel syrup, a couple of ice cubes, and a good dash of full-cream milk, it was just too good!

DEFINITELY making this again soon, it's almost spring time now so I'll need something to cool me down. haha (That's Australia for you..)

[AZKAHUNA]

Since felt is a fiber is there any evidence that it could be harmful because of it's manufacturing process? Like solvents.

[Broom]

Traditional felt was prepared with mercury compounds (hence, "mad as a hatter" - making felt hats led to mercuric poisoning.)

AFAIK modern felt, usually (but not always) polyester, doesn't contain extra chemicals... but that's not much assurance.

[domesticGeek]

Most felt that you'll find in craft stores is polyester, but wool felt is still out there -- it's probably easier to find in fabric stores. I'm not sure what chemicals are used to produce either synthetic or all-wool felt, but it's likely that some sort of bleaching goes on to get the pure white felt.

You can always make your own felt if you can find the "roving" -- which is the cleaned and carded wool. Water + agitation + temperature changes = felt! (or even just water + agitation, if you have the time)
If you can get information about how the roving was processed, then you can have a much better idea of what chemicals (if any) were involved.

My personal preference would be to *not* use a synthetic felt, and probably not a wool felt purchased at a store, for exactly that concern: not knowing what chemicals were used. But I would be fine using felt that I made, or other items that met my own idea of what is 'food safe.'

[DustyBoots]

I hope that's a burr grinder, not a blade grinder. All barista credibility goes out the window if it's a blade grinder. ;)

[LeDesordre]

its a baratza maestro conical BURR grinder, good lookin out!

[kretzlord]

call me stupid, but can i ask what the difference in end product is between the grinders? I love coffee, but don't have the deep knowledge that a barista would have. Is it that a grinder gives a more even/fine grind?

[DustyBoots]

It's definitely something like that. A burr grinder gives a more even grind, while also producing less of the ultra-fine dust that a blade grinder creates. Overall, a burr grinder gives a more consistent grind.

[cwalraven]

Can you use the felt more then once or is it a one time thing?

[LeDesordre]

Hey there!

You can rinse the felt out and let it dry on a dish rack and reuse it!

[cwalraven]

thanks

[Kurzer]

Hi :-) Tried this but not sure what happened.

Followed the instructions to the letter. Coffee used was Starbucks Tribute blend, they ground it as coarse as they could at the store. The bags set for 16 hours.

After draining (really does take forever) the coffee had a powder or texture taste to it, not sure what that is or how it happened but it doesn't taste good at all. Thought it may have been the felt? (Michaels white felt, .89c per square). Can you give me any insight as to why it might have turned out this way? I am really excited to brew this, everyone says it's sweet and full of caffeine.

Thanks for your input, an entire set of new materials awaits replies to try again.

[nounclejesse]

Cold brewed coffee has oils that not only taste wonderful but add to the cold "mouth feel". Ground the coffee as course as possible and use a Gold Cone filter found in grocery stores. They are reusable and let the oils through. I've used this method for years and am still on the first cone. The felt and paper filters catch the oils.

[scarlettdjd]

So -- just to be clear -- you wind up with *2* 'coffee bags" --- -they are not nested, right?

[Ludwig Von Mech]

(removed by author or community request)

[Broom]

"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".

[Ludwig Von Mech]

http://www.snopes.com/food/prepare/suntea.asp

[Javin007]

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?

[Javin007]

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.

[kretzlord]

and kudos go to javin007 for both an opinion and the (exemplary) ability to back it up. And we appreciate your service!

[Broom]

Agreed!

[smalcolm]

Just want to remind everyone, coffee beans are -roasted- (you know, "cooked") before being ground.
So any issues with "sterility" are moot.
Hot brewing does not cook or sterilize anything, so cold brewing is just as safe as hot brewing given the fact that the coffee beans, as I said in the beginning, are already -roasted-.
And to be honest, if contaminants in your tea or coffee are an issue, you might want to re-examine where you're getting your product.

[H3PO4]

You're not supposed to boil the water for any type of tea or coffee. It ruins the flavor. Also, the only way it would sterilize anything is if you put all the tea or coffee in water and boiled the whole thing.
Billions of Americans drink coffee prepared in drip coffee makers (which do not boil the grounds) every day without problems, so I think we'll be okay.

[Ludwig Von Mech]

The whole point of coffee and tea is a non-alcoholic beverage that is safe to drink because Boiling the water kills bacteria. That makes the water safer to drink, and puts the cue to the Victorian explorers saying of "He who drinks water dies First". Examples abound in less than pristine water conditions. I am not paranoid, I am just careful. You should try a round or two of amoebic dysentery, and then you might be careful, too.

[Broom]

Boiling does not kill all the bacteria in water, and it is even less effective when it is not allowed to full-boil for several minutes. Coffee and tea did not gain popularity because they were safer than water; they were the first caffeinated drinks in Europe.

[H3PO4]

Well I don't know where you live, but here in the US we have drinking water standards and we don't have to boil our water for it to be safe. If your water is unsafe, plan on boiling it for at least 10 minutes because otherwise you're wasting your time. Either way, you should never put tea or coffee in boiling water unless astringent, bitter flavors are your thing.

[maintann]

No wonder Americans make such lousy tea. Tea should be made with cold water freshly boiled & made in a prewarmed pot. Sounds silly but try it; there is a difference in taste!