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

Question

I recently rediscovered the joys of cold-brewing coffee. (One level cup of rough-ground beans, 4-1/2 cups of cold water, steeped overnight and strained, produces a rich coffee concentrate. A shot or three of concentrate in a mug topped with hot water makes a cup of coffee; poured over ice and milk makes a fantastic iced coffee drink.)

The information I've found online is contradictory. One site says this method produces a drink with less caffeine than traditional hot-brewed coffee; another says it actually contains more caffeine.

On the one hand, there's the heat in the traditional method. On the other hand, the beans are in contact with the water for twelve hours in the cold method. It seems as if the caffeine content could be identical? While the beans used will, of course, alter the outcome, does anyone know for certain if cold-brewed coffee has more or less caffeine than hot-brewed?

Answer 1

According to the Wikipedia article on caffeine, its solubility is drastically different between room temperature and boiling (2.17 g/100 ml room temperature to 67g/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 or ~.0004 to .00065 g/ml). If you can find similar information about cold-steeped coffee, it might help.

Answer 2

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

Answer 3

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.

Answer 4

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!

Answer 5

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).

Answer 6

If you're willing to pay for the answer, or if someone on here has access to http://www.sciencedirect.com/ alreaday, you can try getting this journal article, though it doesn't mention cold-brewing in the abstract.

Answer 7

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.

Answer 8

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.

Answer 9

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.