Hot Coffee vs Iced Coffee

December 9, 2003 12:10 PM

This comment by furiousthought reminded me of a coffee question for which I have never been able to get a sufficient answer. [more inside]

I am a coffee fanatic who is very particular about all things coffee bean. Although it makes my father cringe (he's a bigger fanatic than I am and thinks ice coffee is heretical) I do drink ice coffee during the summer months. One thing I've noticed is that I do not seem to get the same caffeine kick from ice coffee that I do from hot coffee. I'm sure it doesn't have anyting to do with dilution since I use extremely strong batches of coffee to make coffee cubes. Is this just in my mind or is there a reaction between the heat and caffeine which makes the hot coffee more potent? I've asked this question elsewhere but never received a good answer and I don't want to get involved with coffee UseNet groups.

posted by anathema to food & drink (23 comments total)

I'd probably sit on the yes, there is a reaction with temperature side.

I generally detest caffienated hot drinks, but have made exceptions at times. Each time I felt WAY more buzz than I'd ever get from a half-case of pepsi or 2 litre bottle of iced tea. That could also be due to dilution, though.

Just a moment, gotta use the can again.
posted by shepd at 12:24 PM on December 9, 2003

if you want strong cold coffee, find a toddy coffee recipe. it's cold brewed concentrate and does not contain the oils you get from hot brewing it, so it is very low acid. it's perfect for making ice coffee drinks.
posted by Hackworth at 12:40 PM on December 9, 2003

Poking around in various places, it looks like several things are going on. First, the kind of coffee you make is going to make a difference - darker roasts apparently tend to cook off the caffeine a bit more. There's dispute over how exactly the brewing affects caffeine, but it looks to me like slower brewing processes will extract a bit more.

Assuming you've controlled for that stuff -- I'd bet the caffeine breaks down as the coffee cools. I know the chemistry changes in a number of ways after brewing, and I wouldn't be at all surprised if that were one of them. So it may well be that you're always going to end up with a less-caffeinated drink once you've let it cool.
posted by nickmark at 12:58 PM on December 9, 2003

Of course I'm no authority, as coffee isn't the kind of brewing I tend to obsess over...
posted by nickmark at 12:59 PM on December 9, 2003

I have conrolled for those things. Slower brewing does extract more caffeine, evidenced by the ability of those who drink espresso all day not to grind their teeth into stubs.
posted by anathema at 1:03 PM on December 9, 2003

Coffee does indeed break down after time, hot or cold. Hot coffee kept hot breaks down immediately, which is why most coffee shops have one hour timers on their urns. Iced coffee has a shelf life of approximately 4-8 hours, depending on who you speak to. The best way to retain the flavor, and punch, of coffee is to add milk to it. This is especially so for espresso, which has a shelf life of 10 seconds. If you ever get a chance, step behind the counter of a coffee shop and watch the baristas pull shots. A shot of espresso pulled by a $14,000 La Marzocco machine has a beauty that's unimaginable.

The type of coffee and its roast are also crucial elements. Latin American and some African coffees tend to be more acidic in flavor. They don't have more acid. They have more of a tart taste, hence "acidity". Indonesian coffees are fuller bodied and have a smoother, lingering taste to them. There are exceptions to these generalities, of course. Colombia Supremo, depending on its farm and distributor, is a very subtle, light-bodied, hint of nut coffee that is very different than most Latin Americans.

The roast is important because, indeed, the darker the roast, the less caffeine the bean retains. French Roast, Italian, Vienna, are all types of roast. Very dark, almost smoky. The origin of the coffee has nothing to do with roast.

If you want a damn good iced coffee straight up, and are willing to pay for it, ask for an Iced Americano at your local coffee shop. Espresso has the biggest bang of caffeine and flavor for the buck, so Iced Americanos (espresso and water, iced) are great shots in the arm. If you MUST freeze your coffee, which I highly discourage because the art of coffee is lost (know anyone that freezes wine), use a latin american coffee, blend or single-origin, and understand that a lightly roasted bean looks tan, not brown. Starbucks coffee is mostly dark brown to black because they use a very deep roast. Most Americans, however, are used to a lighter roast.
posted by BlueTrain at 1:18 PM on December 9, 2003

My above comment is all over the place, I know. I have a shitload of experience with coffee, roasting, handling, experimenting, etc. and have a difficult time focusing my thoughts to bullet points. Ask me specific questions, and I become more useful.
posted by BlueTrain at 1:22 PM on December 9, 2003

Espresso has the biggest bang of caffeine and flavor for the buck

But I thought espresso had a lower caffeine content, no?
Can you recommend a good resource for experimenting with home roasting?
posted by anathema at 1:28 PM on December 9, 2003

Yes, less caffeine per serving, but more caffeine based upon volume. You can control the number of shots put into a beverage, coffee is pre-made.

http://www.coffeescience.org
http://www.coffeeresearch.org
http://www.coffeegeek.com

Honestly, unless you're willing to spend a few grand on a decent roaster, I don't consider it worth the trouble. Home roasting is for those who truly appreciate the flavor, body, and feel of coffee, and can afford to invest. If you're in a bigger city, start researching coffee shops. There are enough commercial roasters out there that to start out, all you have to do is experiment with them.

I feel that way about espresso machines for the home, as well. Under $1000, there aren't many good machines. My girlfriend just opened her own coffee shop and wound up purchasing a machine that cost half of the initial start-up fees. It was worth every penny, no doubt, but you pay for quality.
posted by BlueTrain at 1:45 PM on December 9, 2003

Oh yeah, and if you do roast at home, remember, you have to find a dealer that offers decent green beans, which is just as difficult as finding a coffee roaster that suits your palette. Green beans come from all over the world and look exactly alike, so until you understand the fundamentals of good coffee, cupping, etc, it's like playing the lottery.
posted by BlueTrain at 1:48 PM on December 9, 2003

Just some guesses based on elementary chem:

1) Most chemical reactions occur faster with heat. The complete lack of heat - absolute zero - means no molecular motion, no opportunity for ions to exchange, etc. Perhaps you're able to absorb/use more caffeine from a hot solution. Not sure about this, since your body will cool down a hot bev and warm up an iced one once it's inside you.

2) Most solvents can dissolve more when hot. Perhaps some caffeine is precipitated and becomes a suspended solid in the cold water, and is therefore more difficult for your body to absorb.

/talking out of my ass
posted by scarabic at 1:50 PM on December 9, 2003

- Caffeine is really soluble in water (22 mg/mL at 25°C) but is even more so near boiling (670 mg/mL at 100°C). Extraction is really efficient for normal, boiling water methods. In fact, caffeine is pretty much the first thing into the water from the beans. If you take the first cup out of a drip-maker, you're getting pretty much the whole shot of caffeine in the basket.

- Caffeine is really very difficult to precipitate from fresh water. Once dissolved, it's not coming out.

- Temperature is probably the determining factor here, but not because of the brewing issues. Caffeine is absorbed by the mucous membranes in the mouth and throat right into the blood stream (and later in the stomach, of course). Hot caffeine zips through the membranes much faster than cold, probably 100s to 1000s of times faster.

So:
- Hot coffee, like snorting cocaine, is a big, fast hit.
- Cold caffeine, in a coke or an iced coffee, is like getting a slow intravenous drip, a long mellow high.

Wallah.
posted by bonehead at 4:03 PM on December 9, 2003

Interesting. Thanks, bonehead.
posted by anathema at 5:18 PM on December 9, 2003

I roasted some Colombia Supremo (my favorite for drip brewing) a few weeks ago and took some pictures of the process.
posted by planetkyoto at 1:36 AM on December 10, 2003

This is especially so for espresso, which has a shelf life of 10 seconds.

Which means what, exactly? I'm genuinely curious. If this is really the case, then there's got to be very few people on this planet who've actually had a proper espresso, then.

Wallah.

[pedant] I assume you mean 'voila'. [/pedant]
posted by stavrosthewonderchicken at 1:43 AM on December 10, 2003

Assuming you're in the US, try the following for home roasting info:

alt.coffee (superb resource, better than most Usenet)

Randy Glass's site (one enthusiastic Sherman's personal account of getting into roasting for espresso from a standing start)

Sweet Maria's (coffee merchant's - great selection of green beans and roasting equipment, also some good information on the site about roasting, tasting notes and roasting recommendations for different beans etc.)

I've been home roasting for about a year now - have dabbled with two bottom-end roasters (Fresh Roast + and Imex). Both have produced results a hundred times better than buying beans (but then again, it's hard to get good, fresh, roasted coffee in the UK). In fact, I've found that it is essentially impossible to get a drinkable espresso out of my La Pavoni Europiccola without home-roasted beans and a half-way decent grinder (a Rancilio Rocky in my case).

One warning - getting into home roasting is likely to prove fairly expensive - there are a couple of bits of equipment that you won't want to skimp on (notably the grinder if you plan to roast for espresso). It can be a bit more reasonable I suppose if you use drip or cafetiere primarily - especially because by buying green beans you'll generally be getting a much better standard of coffee for a similar or cheaper cost.

If you want me to pull together my list of coffee bookmarks from home and email them to you, let me know.
posted by bifter at 2:34 AM on December 10, 2003

How was the liquid form, planetkyoto?
posted by anathema at 4:01 AM on December 10, 2003

Pretty good, but I went too slow, methinks, for fear of scorching. I'll get better.
posted by planetkyoto at 6:00 AM on December 10, 2003

Mais bien sûr, monsieur le-poulet-merveilleu.
posted by bonehead at 6:54 AM on December 10, 2003

The best way to retain the flavor, and punch, of coffee is to add milk to it.

How does the milk add punch?
posted by anathema at 4:46 PM on December 10, 2003

This is especially so for espresso, which has a shelf life of 10 seconds.

Which means what, exactly?

Coffee, as soon as it's brewed, immediately decomposes, until the aroma, flavor, and balance of oils and water are lost. This is especially so for espresso, which approximately 10-30 seconds after it's poured, depending on who you ask, is "dead". The best way to handle espresso is have it pulled into a demitasse glass and immediately consumed, provided you can handle the heat of the drink. Make sure, however, that the shot "looks good", retains all three components, and pours within the designated time, which varies by machine.

How does the milk add punch?

Milk doesn't add punch, it helps espresso retain the original strength and flavor. Obviously it's now diluted with milk, but espresso doesn't keep well at all, so milk is better than the alternatives, water or nothing at all.
posted by BlueTrain at 10:01 PM on December 10, 2003

Cool, thanks. I do need to try that, next time I get to someplace that actually serves brewed coffee (the nearest at the moment would be a 2 hour bus ride, I think) as opposed to instant chemical death.

Ah, Korea.
posted by stavrosthewonderchicken at 2:09 AM on December 11, 2003

Good stuff, BlueTrain. Thanks.
posted by anathema at 6:06 PM on December 11, 2003