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I had gone completely cold-turkey on caffeine for a while due to anxiety issues, and I'm slowly reintroducing caffeine to my diet. I have read in many places that freeze-dried instant coffee has less caffeine than the equivalent amount of fresh-brewed, but I haven't seen any explanations as to why. Is it something inherent to the freeze-drying process which causes this change?

And, of course, how much lower is the caffeine content in general?

fluffy
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  • Science in the Public Interest has a [table](http://www.cspinet.org/new/cafchart.htm), but the values are pretty much all over the place. I don't have the time to do any real analysis right now. – Joe Mar 20 '13 at 20:42
  • Not an answer, but a thought for your situation - you could try mixing your own 'half-caf' blend, with your preferred ratio of decaf beans/grounds to regular. Or drinking a light tea for the caffeine and decaf coffee if you miss the flavor. Interesting question, though. – hunter2 Jun 28 '13 at 06:26
  • @hunter2 Sure, I do that too. :) I was just curious about the science behind the lower caffeine content of freeze-dried. – fluffy Jun 28 '13 at 19:05
  • Our sister site Coffee SE is discussing this, too: http://coffee.stackexchange.com/questions/2323/does-instant-coffee-give-a-lesser-buzz-high-than-conventional-filter-french-pres – Stephie Dec 20 '15 at 14:12

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Caffeine is water soluble, but it takes a bit of time to be absorbed by water.

What determines the caffeine content of a coffee process is how much time it spends with/in water.

For example, a bodum French press will pick up more caffeine from the coffee since the grounds stay soaked for a while. Drip coffee will have more than a single espresso (common misconception is to think the opposite).

It's likely that the instant coffee process passes the water through the coffee under pressure and faster than drip. This will naturally prevent the caffeine to be absorbed in water as much.

Besides using decaf roast, what you may wish to do is get an americano coffee made with one or two Ristretto shots of espresso. A Ristretto shot is usually pull away after 10 seconds.

Take a look at this analysis from the Mayo Clinic for the actual Caffeine values.

MandoMando
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  • Thanks, and yeah, I usually get a ristretto americano when I go to a coffee shop, but I'm interested in options vis-a-vis cheap and accessible when I'm at my desk. :) Your answer seems plausible but I'm holding off on accepting it in case something more authoritative comes along. – fluffy Mar 20 '13 at 22:06
  • It's highly doubtfull that the makers of 'Folgers Instant Crystals' use the highest quality, most select, caffeinelicious beans as starting material for the brew and freeze-dry process. – Wayfaring Stranger Nov 08 '14 at 14:47
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    @WayfaringStranger Who said anythign about Folger's? There's other brands out there, some of which are actually not completely terrible. (Douwe Egbert's, for example.) – fluffy Feb 14 '15 at 19:57
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Instant coffee is not dried beans, its dried coffee. Water is added to finely ground roasted beans and then one of many methods is used to preserve it. As you are adding water to coffee that has already had a small amount of water added to it, it is a lower concentration of coffee, and thus less caffeinated. It is also often a dark roast, which has had more caffeine roasted off.

Results vary as to how much less caffeinated it is from half as caffeinated as drip coffee to 3/4 as caffeinated.

Careforfree
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  • This doesn't really answer my question, and only states obvious things that weren't being asked. And, I'm reintroducing caffeine because I miss having the option of using it to wake up when I need it; I've been drinking decaffeinated coffee (with its much lower caffeine levels) for quite some time. – fluffy Mar 24 '13 at 22:53
  • I don't really understand your argument here. Surely you always use enough instant coffee to result in the same concentration of coffee you'd want normally, so it's the same amount of flavor and same amount of caffeine. – Cascabel Mar 25 '13 at 02:48
  • All of the research I've seen has instant coffee's caffeine concentration as less than drip brewed. http://www.energyfiend.com/caffeine-content/coffee-instant http://ndb.nal.usda.gov/ndb/foods/show/4185?fg=&man=&lfacet=&format=&count=&max=25&offset=&sort=&qlookup=instant+coffee – Careforfree Mar 25 '13 at 13:44
  • @Careforfree Yes, and I have found plenty of information about the what. What I was asking was the WHY. – fluffy Jun 27 '13 at 22:29
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Instant coffee may not be lost during processing and just have a lower caffeine content simply because less coffee is used in making the cup. One tablespoon of instant coffee in 8 oz of water gives a brew with TDS of .75%, about 30 - 45% lower than the recommended TDS for coffee. https://www.scaa.org/PDF/resources/golden-cup-standard.pdf An 8 oz cup normally brewed with one tablespoon and containing 55 mg of caffeine, would contain 80-85 mg when brewed with matching TDS.

At similar TDS, instant coffee might have less caffeine, because it is often extracted at higher temperatures and pressures than drip-brewed coffee. This would make it easier to extract more solids less soluble than caffeine than in normal conditions, resulting in an extract with a lower caffeine to total solids ratio than in drip brew.

In regards to process related losses: If freeze drying, caffeine could be lost due to sublimation. However, the rate at which it does is might not be significant, since caffeine seems to be normally heated above 100 C, in a vacuum, when intentionally sublimated.

If the coffee was spray-dried instead, caffeine could be lost with evaporating water vapor. A major loss of caffeine during roasting has been attributed to this. http://www.sciencedirect.com/science/article/pii/S030881461100762X

crispy
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Instant coffee has lesser caffeine because it was processed with lower heat.

caffebox
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    Thanks. Got any citations to back that up or credible explanations for why that might be? – fluffy Jun 13 '13 at 20:56
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The caffeine content is also dependent on how long the coffee steeps. So, since it is instant, it will have less time to create more caffeine. Unless you have VERY hot water and let the instant coffee steep for a long time :p which may be gross.

Erin Rampy
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  • This is about instant coffee, where you drink all of it whatever state of solution it is, so caffeine intake is always the same (assuming that bioavailability does not differ). I'd rather assume the caffeine content is kept low in order not to wake up the drinker enough to turn medieval on who gave him vile-tasting instant coffee :) – rackandboneman Dec 07 '15 at 17:54
  • Yeah, instant coffee is pre-steeped and freeze-dried in that state. The steep time is potentially unlimited - it's probably all brewed in a gigantic batch and then sent off into the freeze drier. Also the caffeine isn't "created" at the time of steeping, it just leeches into the water at that point. – fluffy Dec 08 '15 at 02:54