# How is coffee decaffeinated these days? The process is fascinating! **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [June 13, 2004, 8:45pm UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169 "2004-06-13T20:45:21Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [June 13, 2004, 8:45pm UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/1 "2004-06-13T20:45:21Z")
I thought they still used nasty, toxic chemicals. That’s apparently not the case any more. The supercritical fluid CO[sup]2[/sup] method is a fascinating process! See [How is coffee decaffeinated?](http://antoine.frostburg.edu/chem/senese/101/consumer/faq/decaffeinating-coffee.shtml) > [@](#): > > Supercritical fluid CO2 extraction > When a sealed vial containing both gaseous and liquid carbon dioxide under high pressure is heated, the liquid density drops while the gas density rises. If the pressure is above 72.8 atm, and the temperature rises above 304.2 K, the density of the liquid and the density of the gas become identical. The meniscus between the liquid and gas phases vanishes. The carbon dioxide becomes a supercritical fluid which has both gaslike and liquidlike properties. The fluid fills the container like a gas, but can dissolve substances like a liquid. Supercritical fluid carbon dioxide is an excellent nonpolar solvent for many organic compounds, including caffeine. > > The extraction process is simple. Supercritical carbon dioxide is forced through green coffee beans. Its gaslike behavior allows it to penetrate deep into the beans, and it dissolves 97-99% of the caffeine present. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [June 13, 2004, 9:08pm UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/2 "2004-06-13T21:08:41Z")
Wow, that’s pretty cool! There’s also talk of genetically engineering out one of the precursors to the caffeine, so the plant grows decaf out of the ground. Of course, then one has to sell the idea of genetically modified coffee to the public, and GM foods seems to be a tough sell. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [June 13, 2004, 9:17pm UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/3 "2004-06-13T21:17:32Z")
Here’s news for you… CO[sub]2[/sub] is a chemical! And pretty toxic. Sure, it evaporates off, but so did the solvents previously used. ---
**Author:** ![clayton\_e](https://avatars.discourse-cdn.com/v4/letter/c/c57346/32.png) [@clayton\_e](https://boards.straightdope.com/u/clayton_e)\ **Post date:** [June 13, 2004, 11:40pm UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/4 "2004-06-13T23:40:44Z")
So… considering we’re not using the previous solvents and that we are using the toxic CO2 which evaporates off completely… its safe. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [June 14, 2004, 12:25am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/5 "2004-06-14T00:25:36Z")
I wonder: 1 What else is removed or 2 Does caffene actually give coffee its good taste ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [June 14, 2004, 12:38am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/6 "2004-06-14T00:38:06Z")
> [@Colophon](#): > > Here’s news for you… CO[sub]2[/sub] is a chemical! And pretty toxic. Sure, it evaporates off, but so did the solvents previously used. How toxic can CO[sub]2[/sub] be? Don’t we exhale it? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [June 14, 2004, 12:41am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/7 "2004-06-14T00:41:40Z")
> [@Finagle](#): > > How toxic can CO[sub]2[/sub] be? Don’t we exhale it? Uh, yeah - that’s _why_ we need to exhale it. It’s a waste product. But don’t worry - you’d need a relatively high concentration of it in the air you breathe before it would harm you. ---
**Author:** ![Raygun99](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@Raygun99](https://boards.straightdope.com/u/Raygun99)\ **Post date:** [June 14, 2004, 12:55am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/8 "2004-06-14T00:55:02Z")
> [@Colophon](#): > > Here’s news for you… CO[sub]2[/sub] is a chemical! And pretty toxic. Sure, it evaporates off, but so did the solvents previously used. Drink much carbonated soda? ---
**Author:** ![Cinnamon\_Girl](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@Cinnamon\_Girl](https://boards.straightdope.com/u/Cinnamon_Girl)\ **Post date:** [June 14, 2004, 1:13am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/9 "2004-06-14T01:13:45Z")
> [@clayton\_e](#): > > So… considering we’re not using the previous solvents and that we are using the toxic CO2 which evaporates off completely… > > its safe. That’s not entirely accurate. The previous solvents you might be referring to include ethyl acetate and methylene chloride, which seems to be more readily linked to cancer risks. Yes, CO2 evaporates as the beans cool, but it’s not much of a different result than solvent methods in which the solvents are burned off in the roasting process. Methylene chloride evaporates at 40 degrees celcius; whereas, coffee is roasted at upwards of 205 degrees celcius. Further, toxity levels are so minute in brewed roasted coffee, it’s not even worth worrying about. At 200 ppm, methylene chloride is significantly toxic, but the FDA limits levels in foods to 10ppm. However, according to the FDA, coffee generally contains only 0.1 ppm. Not enough to even blink. But, to play devil’s advocate, if that is worrisome to decaf drinkers, there are studies out there that link lowered cancer risks to caffeine intake. There is also the Swiss Water Process in which green beans are soaked in hot water to remove caffeine and other constituents. The caffeine- and flavanoid-laden water is then filtered through carbon or activated charcoal thereby removing the majority of caffeine molecules. Finally, the beans are re-soaked in the decaffeinated water to reintroduce to the beans the remaining flavor compounds. No chemicals are used. Granted this method is used less often due to perceived loss of flavor, but there is no indication whatsoever this method is anything less than perfectly safe. Linkity-links for the curious and cite-needers: [Key Facts about Decaffeination](http://www.worldwidemart.com/choice/decaf.html); [There’s more to coffee than firing up the brain](http://216.239.51.104/search?q=cache:yvQWYwZnCxIJ:straitstimes.asia1.com.sg/columnist/0,1886,56-214143--1070834340,00.html+starbucks+decaffeination&hl=en); [Coffee Science Information Center: Coffee and Caffeine - Decaffeination Processes](http://cosic.org/caffeine/decaffeination/) ---
**Author:** ![Cinnamon\_Girl](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@Cinnamon\_Girl](https://boards.straightdope.com/u/Cinnamon_Girl)\ **Post date:** [June 14, 2004, 1:18am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/10 "2004-06-14T01:18:15Z")
> [@kanicbird](#): > > I wonder: > > 1 What else is removed > > or > > 2 Does caffene actually give coffee its good taste 1. See my above post on what else is removed: sometimes other flavor compounds can be removed in certain processes. 2. If I can remember right, caffeine does have a flavor. It’s bitter. Does it contribute to its taste? Seriously. I think you’re missing the point… hehe 🙂 ---
**Author:** ![1010011010](https://avatars.discourse-cdn.com/v4/letter/1/ea666f/32.png) [@1010011010](https://boards.straightdope.com/u/1010011010)\ **Post date:** [June 14, 2004, 1:28am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/11 "2004-06-14T01:28:58Z")
What do they do with all the caffeine? That’s what I’ve always wondered. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [June 14, 2004, 1:47am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/12 "2004-06-14T01:47:16Z")
Caffeine is sold in tablet form (“No-Doz”) and added to other drugs like Exedrin. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [June 14, 2004, 2:01am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/13 "2004-06-14T02:01:53Z")
> [@1010011010](#): > > What do they do with all the caffeine? > That’s what I’ve always wondered. From the OP link > [@](#): > > Coffee manufacturers recover the caffeine and resell it for use in soft drinks and medicines. The caffeine-laden CO2 is sprayed with high pressure water and caffeine is then isolated by a variety of methods, including charcoal adsorption, distillation, recrystallization, or reverse osmosis. IIRC caffeine is also in many name brand asprins. It helps it work more quickly. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [June 14, 2004, 2:08am UTC](https://boards.straightdope.com/t/how-is-coffee-decaffeinated-these-days-the-process-is-fascinating/250169/14 "2004-06-14T02:08:24Z")
> [@astro](#): > > IIRC caffeine is also in many name brand asprins. It helps it work more quickly. Well, not aspirins - aspirin is a specific chemical that is different from caffeine. Some other pain relievers, however, have caffeine in them on top of the other pain relieving compounds. Excedrin, as has been mentioned, is one of them.