Caffeine content of cold-brewed coffee: higher or lower than hot-brewed?

There's an article from MSNBC which quotes the Toddy company. The Toddy company makes a device for easy brewing cold brewed coffee. Apparently, in a side by side test of Toddy cold brewed with Star Buck's hot brewed, the caffeine content was ~30% less in cold brewed than in hot... I'll go with that. http://today.msnbc.msn.com/id/5728227

According to the Wikipedia article on caffeine, its solubility is drastically different between room temperature and boiling (2 g/100 mL room temperature to 66 g/100 mL at boiling). I assume this means it's easier to get caffeine into boiling rather than cold water, but the drastically longer steeping time may counteract this. It's worth noting that the solubility is far higher than the actual amounts of caffeine that's in coffee.

Farther down the page it mentions caffeine per liter of liquids like coffee (386-652 mg/L). If you can find similar information about cold-steeped coffee, it might help.

Its interesting to see all of the responses. At Kohana Coffee we make cold brew coffee concentrate commercially. Our caffeine numbers come to about 80 mg of caffeine per oz of cold brew concentrate. Our mix ratio for use is 1 part concentrate to 2 parts milk or water. Typically, a 16oz cup of iced coffee would be 3 oz concentrate, 6 oz milk/water plus ice to fill cup. 240mg of caffeine. It is, however, totally dependent upon the user and how they make their drink.

What we've found from years of watching consumers (that is in no way scientific - but more of a user variable) is that cold brew is normally ingested much more quickly than a hot cup of coffee. The user feels the caffeine faster and thus believes there is more caffeine.

Its a simple perspective but one that we've seen repeatedly through the years.

I work at Peter Larsen Kaffe in Denmark, where I make cold brew. I used 1 kg of coffee and 10 liter water, letting it stand for 17 hours. Then I sent it to Steiner Laboratory, where they measured the content of caffeine to be 920 mg per liter of the cold brew.

You can pull most of the caffeine out of a bag of tea by steeping in 180F water for 10 seconds.

Combining this knowledge with Brendan Long's excellent research, I interpret this to mean that all the caffeine available will get pulled out of the coffee long before a 12 hour cold brew steep is finished.

Conversely, it's very unlikely that a cold brew significantly increases the amount of caffeine available in coffee.

There are so many conflicting opinions on this, but I have noticed that there are also many "recipes" for making the original coffee concentrate. One recipe calls for a coffee/water ratio of 1oz/12oz (1 part to 12 parts) and another recipe says to use 1/3 cup of coffee to 1 cup of water (1 part to 3 parts). The Toddy company tested their coffee, made with a specific amount of coffee/water. Someone else makes the concentrate stronger by using a higher ratio of coffee to water, which results in a higher percentage of caffeine. It makes sense to me!

Caffeine is much more soluble in hot water, true. But 100mL of room temperature water will still dissolve 2000mg of caffeine, so carrying capacity of water isn't a limiting factor.

The better determinant of caffeine content of brewed coffee isn't temperature at all! It's... the caffeine content of the roasted beans. Roasting decomposes caffeine, so lighter roasts (of the same beans) are higher in caffeine than darker roasts. Also, different varieties of beans have differing caffeine content (too much variation to go into here).

Grinding the roasted beans more finely will cause the water to leach the solutes more quickly, but in a 1+hour cold brew process, there wouldn't be much difference in product between coffee that was ground to a Turkish grind (very fine/powder) vs a drip machine grind.

As far as flavor, there is clearly a difference between cooled hot-brew and cold brew. This has to do with the relatively varied solubility curves of the flavor-producing compounds in the coffee.

Hold on, let me consult the maestro...

Okay. Based on the coffee section, you will get fewer bean solids per cup when you go colder. I think one can extrapolate from that knowledge a lesser amount of caffeine will be extracted. In addition, "Overnight extraction in cold water doesn't obtain as many aromatic compounds from the ground coffee as the hot-water methods." (Harold McGee, On Food and Cooking, revised edition 2004, p 433, p445, and pp441-448).

Caffeine is a water soluble compound. Naturally decaffeinated coffee and tea is done with cold water. Cold water brewing of coffee usually takes at least 12 hours to extract maximum flavor. I would suggest that it also extracts as much caffeine as hot water brewing. The difference in the brewing methods is primarily the amount of acidic oils released. My cold brewing method involves starting out with 110 degree F water and stirring the brew several times during the steeping of the grounds. I also use a fine grind and do not refrigerate the brew until all of the grounds have saturated and sunk to the bottom of my brew vessel. I prefer as high of a caffeine content as possible in my coffee and tea.

If the question is which brew method results in a higher per oz caffeine content, the answer is that cold brew coffee brewed at a 1:5 coffee to water has significantly more caffeine per ounce than hot brew brewed at a 1:17 ratio. http://www.caffeineinformer.com/the-caffeine-database

If the question is whether cold or hot brew extracts more caffeine per oz of coffee, the answer is that neither method is significantly better at extracting caffeine.

While it is true that hot brew was shown to have 30% higher caffeine contents with the same coffee weight, this difference is mainly because cold brew is brewed in batch, so soluble caffeine is still trapped in the grounds. When the hot-brew caffeine content in the side-by-side test, mentioned in http://toddycafe.com/toddy-news/15/My-coffee-is-cold, is adjusted to the amount of caffeine that would yield from a french-press (~70% of drip-brew http://www.coffeeconfidential.org/health/cut-down-caffeine/), the 61 mg of caffeine in hot, drip-brew caffeine drops to 44 mg per 100 g. This is nearly identical to the 40 mg of caffeine found in the cold-brew.

Cold extracted, or filtered, or press coffee contains significantly less caffeine and significant less oils that hot brewed coffee.

Now if you choose home methods, by using your French press for instance, then this will be less the case. The caffeine percentage is because of the sponge filter. As cold water is the major method of decaffeinating coffee, it makes sense that as the coffee steeps in the water, the caffeine is extracted. Then when the plug is pulled and the coffee in solution runs through the sponge, the now-in-solution caffeine is extracted, as are the oils. Cold water or hot water doesn't matter, it's the sponge filter.

Source: as the ex-wholesale VP at Starbucks, married to the woman who as F&B Director at Starbucks, developed Frappucino and devised the system for the Gold Standard of food & beverage.

This is actually comparing apples to oranges. Remember, the cold brew systems develop a concentrate. Depending on the reconstitution method, you could have less, more or exactly the same. In plain english - the ratio of concentrate to added liquid dictates the caffeine level.

Let's be logical. If you're comparing how much of the caffeine is extracted in each method, you shouldn't try to deal with what's in the cup.

As @user4620 pointed out, the amount of caffeine in a cup of cold brewed coffee depends not only on the caffeine in the concentrate, but also on the amount of the concentrate used per cup.

I wouldn't characterize this discussion as "apples to oranges," but instead, "apples to an unknown," the "unknown" being the amount of concentrate used per cup. Two things cannot be compared when one of them is unknown.

One toddy recipe instructs the user to use a specific ratio of concentrate to water when preparing a cup of coffee; but then follows with the expected qualification to alter the ratio to taste. My guess is that all toddy directions contain that qualification.

I drink cold brewed coffee because I like the taste. Also, I enjoy cold coffee in the summertime. Whether there is more or less caffeine per cup is not an issue. I can always drink more or make the drink stronger, or if I get drowsy while driving, I can always swallow a No-Doz tablet.

I can tell you that physiologically cold brew has less. Here's how I know. When I do cold brew I will soak one pound of coffee in one gallon of water over night. I will typically soak for no less than 18 hours, but no more than 24. I limit the soak to this time frame because if its less, the coffee is too weak and tastes bitter and any longer it will be too strong. Here's my math. It takes 16 ounces of coffee cold steeped in one gallon of water to produce 16 8 ounce cups of coffee. It takes about 8 ounces of coffee steeped in hot water to make the same amount. Half the coffee for hot steeped. Follow me so far? Here's where the physiological part comes in. If I drink one 8 ounce cup of hot steeped coffee every day for one week, then immediately go to same amount of cold steeped coffee every day for a week, I will always get headaches. The headaches are the number one symptom of caffeine withdrawal. I have had the same symptoms three separate times. I have never had the typical jittery symptoms with increased caffeine when going from hot to cold steeped coffee. Always the headaches. So in my estimation, I believe it is at least the noted 30% less caffeine that I have read online, but I actually believe it to be even less. Both Caribou and Starbucks are listed as having about 25% less caffeine in their cold drinks, but I believe Caribou uses cold press and Starbucks Ices their hot press so I question the validity of the Starbucks values.

In brief, from my research into cold-brewing in preparation for selling 1000 gallons of cold brew at a festival:

Like most teas, if you soak the beans for long enough at any temperature, you will get about the same solubility as a few minutes at high temp... this varies per bean of course, and per what chemicals you're interested in dissolving, but 48 hours is plenty of time for cold brewed coffee. The health and flavor advantages of cold brew are many, but outside the scope of this OP.

Per the bottle, Chameleon cold brew coffee has 240 mg caffiene for 4 ounces (though this is meant to be mixed with equal parts water, so 240 mg for 8 oz).

Last I checked, stabucks was amongst the highest in caffeine content at around 220 mg for this serving size of 8 oz.

At one point, I HAD to have 11 shots of espresso per day to stay "normal." Bad times. Anyway,The iced coffee brewing method at Starbucks varies based on the laziness of the barista. Essentially, half a pot of coffee is brewed using twice the normal amount of grounds, then quickly poured over ice in a pitcher. Caribou cold presses theirs, don't know or care how. (TEAM STARBUCKS!) Here's what I found from their respective websites:

• Starbucks Hot Pike Place Roast - Grande 16oz - 330mg caffeine.
• Caribou Hot Coffee of the Day - Medium 16 oz - 305mg caffeine.
• Starbucks Brewed Iced Coffee - Grande 16 oz - 190mg caffeine (unsweetened).
• Caribou Cold Press Iced Coffee - Medium 16 oz - 230mg caffeine (unsweetened).

So based solely on this, cold press results in more caffeine. From what I know, the roast of the beans is similar in both stores (medium roast for iced coffee) but don't quote me on that. Either way, if you're making a concentrate instead of drink-straight iced coffee, it's going to depend on you using more or less to get the desired affect.

I smile at all these responses, as no science is really quoted throughout to confirm anything. Diane's response is closest to reality because she is correct...cold brew has less caffeine than hot brew, all things remaining equal. A coffee bean has the highest caffeine content before it is roasted, and loses caffeine content the longer it roasts. Thus a medium roast bean will contain more caffeine than an espresso roast bean.

Caffeine loss in the brew process is a factor, as is caffeine loss in the filtration of the cold brew process, as was stated. Keep looking, and you will find someone who may have taken this to a scientific, granular level to confirm that cold brew offers less caffeine than hot brew, all things remaining equal.

"All things remaining equal" means using the same roast, the same amount of coffee bean to brew, the same amount of water to brew, and then finally, a comparison based on an 8 oz. cup of coffee using various dilutions ratios of cold brew to hot water.

Understand that Diane used twice as much coffee for her cold brew than for her hot brew and still presented caffeine withdrawal from the cold brew coffee.

I grow and process coffee, but claim no scientific expertise.

"According to the Wikipedia article on caffeine, its solubility is drastically different between room temperature and boiling (2 g/100 mL room temperature to 66 g/100 mL at boiling). I assume this means it's easier to get caffeine into boiling rather than cold water, but the drastically longer steeping time may counteract this. It's worth noting that the solubility is far higher than the actual amounts of caffeine that's in coffee."

Someone answered with this above, this means that 2g of caffeine is soluble in water at room temperature per 100mL, no cup of coffee is ever that high so that means at room temp you should be able to get the same amount as in hot water, just takes longer.

However caffeine is very volatile, so hot water extracts and eliminates it more than cold...which implies that in a cold brew, more caffeine is retained in the brew and not boiled off. For this reason esspresso actually has less caffeine than traditional brew coffee because of the high heat and pressure..it's a stronger flavor but not a higher caffeine content.