[JOHN Gamel]

JOHN Gamel  asked the Naked Scientists:
   
Dear Naked Scientists,

You cannot possibly find on the earth a more devoted listener than me.

For some reason, the ITUNES websites offers podcasts of your programme that go back several years! Thus I listen to you at home, in my car, while cleaning my house, and while mowing my lawn.

I was a bit disappointed to discover that you weren't truly (as in physically) naked:  if all of you were sitting there bare-assed as you chatted away, the programme would be even more intriguing.

By the way, something similar happened in San Francisco during the 1970s, when the topless craze reached its height. Every block had topless dancers, topless barbers, and topless shoe-shine girls! The tourists loved it, but the novelty soon wore off, and the women put their shirts back on.

Keep up the good work. By the way, I've got a few questions for you:

It's easy to see how they extract caffeine from coffee once its been ground up or brewed, but how the hell do they extract caffeine from whole coffee beans?

Most Cordially Yours,

John Gamel, MD

What do you think?

[Chemistry4me]

I think this should cover it: http://www.perfectcoffees.com/caffeine.html

[chris]

I have a feeling that supercritical CO2 can also be used for this process and, because it avoids the need for potentially nasty solvents that can also rob the bean of flavour, it's the preferred way to do it - I'll check.

Chris

[rmrblacksmith]

I find the best way to extract caffine is through my kidneys

Richard Roberts

[Chemistry4me]

Ah, Touché, touché Mr. Roberts. []

[Yomi]

if you're a coffee lover who prefers to avoid caffeine, you can still enjoy a cup of coffee that delivers rich flavor with decaffeinated coffee.

These are some of the methods currently used for decaffeinating.
 Direct Contact Method
In the direct contact method the beans come directly in contact with decaffeinating agents, such as methylene chloride, after being softened by water or steam. Caffeine is removed by directly soaking the materials in the methylene chloride.

 Indirect Contact Method
With the indirect contact method a water and coffee solution is used to draw off the caffeine. The solution containing the caffeine is then treated with a decaffeinating agent, such as ethyl acetate, and mixed back into the beans for reabsorption of the flavorings.

 Water Processing
This process is similar to the indirect method, except no chemicals are used. The coffee beans are soaked in hot water then the solution is passed through a carbon filter to remove the caffeine.

 Swiss Water Process
In the Swiss Water Process method, the caffeine is still extracted with carbon filters but the beans soak in hot water that is saturated with coffee flavor. The result is caffeine removal without removing the coffee flavors.

It's referred to as Swiss Water Process because a Swiss company originally developed and patented the procedure.

 Carbon Dioxide Processing
With this method the beans are soaked with water-softened materials in highly compressed carbon dioxide. The small caffeine molecules are extracted from the beans allowing the larger flavor molecules to remain untouched. This method retains the best overall flavor of all of the methods used.

Not all of the caffeine is completely removed with any of these current methods. To qualify as decaffeinated coffee in the United States, coffee must have at least 97 percent of its caffeine removed.

Coffee beans are decaffeinated before they are roasted because that's when it has the least effect on the beans flavor.

The reason decaffeinated coffee costs more is because of the additional labor, equipment and material needed to remove the caffeine.

So what do they do with all of that caffeine? The extracted caffeine is manufactured and used mostly in medicines and soft drinks.

As an example, the caffeine content in soft drinks mainly comes from the caffeine extracted from these decaffeination processes. The kola nut accounts for less than 5 percent of the caffeine in cola drinks.

For the past 30 years scientists have done extensive research on coffee and the effects of caffeine. New research has even shown that caffeine has many positive effects.

Some of these effects include more energy, the ability to concentrate better and has even been used as an appetite suppressant.

But not all scientists agree with these findings and coffee and the effects of caffeine will continue to be thoroughly researched.

There will always be a market for decaffeinated coffee because some people just love their coffee without the caffeine buzz.

The rest of the 100 million regular coffee drinkers either love their coffee for the wonderful flavor or enjoy the effects of a caffeine boost. For most of us, I'm sure it's a little of both. [8D] [8D] [8D]

[Chemistry4me]

Dude, please add your references next time. We do not want to get into trouble.

http://www.annamariavolpi.com/coffee04.html

[Yomi]

Oh ya I forgot sorry

[Shadec]

I have a feeling that supercritical CO2 can also be used for this process and, because it avoids the need for potentially nasty solvents that can also rob the bean of flavour, it's the preferred way to do it - I'll check.

Chris

interestingly, it usually uses dry cleaning fluid, called Tetrachloroethylene, or C2Cl4. it dissolves the caffeine and is then sold as a soln. or a solid to highly caffeinated drink companies.
the use of supercritical CO2 has been suggested, and is far safer, but it is not widely used as like almost everything else in our world, it is set up in a certain way, and no matter how much it screws up the environment, it makes them money, so its not going to be easy to change (it is more expensive, needs new infrastructure etc)

[chris]

Thanks C4me for sourcing the appropriate acknowledgement for the answer supplied above, and thank you, Nobel for locating the answer in the first place - very interesting.

Shadec - I agree - although companies are coming around to the green chemistry revolution because there are various incentives and benefits from doing so. The carbon dioxide process is actually quite beneficial because the purification is so simple.

Chris

[Bored chemist]

I think Shadec has got the solvent wrong. The process used to use dichloromethane (paint stripper rather than dry cleaning fluid)
Also, since CO2 is cheaper than DCM (as well as avoiding problems of toxicity and environmental hazard) it's been quite widely adopted.

[Shadec]

perhaps i have, i doubt you could be bothered, but...
  Doherty RE (2000). "A History of the Production and Use of Carbon Tetrachloride, Tetrachloroethylene, Trichloroethylene and 1,1,1-Trichloroethane in the United States: Part 1—Historical Background; Carbon Tetrachloride and Tetrachloroethylene". Environmental Forensics 1 (1): 69–81. doi:10.1006/enfo.2000.0010

ive just one a little research, and it seems that they used C2Cl4 for awhile, but it was replaced with C2Cl2H2, which has now, fortunately, been replaced with supercritical CO2. although methylxanthines are soluble in all three.

i do agree it is considerably better for the environment though