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  1. #11
    gainer's Avatar
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    I haven't tried it, mostly because my brain has other needs for coffee, but I wonder why instant coffee is specified. Is it a matter of convenience, or does it somehow depend on the method of processing of coffee beans to extract the coffee essence? When I drink coffee, I would rather wait on the coffee maker than drink the instant stuff, even Folger's.
    Gadget Gainer

  2. #12
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    Well IMHO instant coffee is a lot easier to make 4x strength as needed by cafeinol.
    Besides being el-cheapo of cours e
    Mama took my APX away.....

  3. #13
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    There was a paper from the RIT guys a while ago about this. When my imagination was excited from coffee developers in 2004 I found it, and even got in contact with the professor who explained that caffeic acid in the rpesence of alkali (washing soda) was the main developing agent.
    That is why mint also worked, the bark of a few trees, and a few other plant extracts as well.
    I have that paper somewhere in the storage room and can not give you a reference from the top of my head.

    Quote Originally Posted by Jordan View Post
    My understanding is that the primary "developing agent" in coffee is in fact caffeic acid, which is a glycoside of 3,4-dihydroxycinnamic acid (a catechol derivative, as Gerald mentioned). Caffeic acid is structurally unrelated to caffeine.
    GEE GOOGLE IS YOUR FRIEND:
    http://www.rit.edu/~andpph/text-coffee.html
    Last edited by titrisol; 11-28-2006 at 02:11 PM. Click to view previous post history.
    Mama took my APX away.....

  4. #14
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    Instant coffee typically is made primarily with Robusta beans, which have about twice the caffeine content of Arabica--but I recall that someone here determined that caffeine in place of the coffee doesn't develop film. There are all sorts of bitter flavors in Robusta beans that are absent in Arabica and that make them a bad primary choice for properly extracted coffee, so whatever the developing agent is, it's probably one of the reasons diner fluid taste so bad.

    In any case, if you want to use on-hand commodity coffee instead of going out for instant, you can make it 4x strength by using about 230 grams of coffee per liter of water. Boiling it would probably get the most extraction. Try to make terrible coffee and you'll probably get a pretty good developing agent.
    Last edited by derevaun; 11-28-2006 at 02:52 PM. Click to view previous post history.

  5. #15

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    Quote Originally Posted by derevaun View Post
    I recall that someone here determined that caffeine in place of the cofee doesn't develop film.
    Out of curiosity, I once tried a mixture of Mountain Dew and sodium carbonate. No dice. As I recall, it actually cleared the film. I have no idea if it was working as a fixer or if it just ate away the emulsion. Probably the latter.

  6. #16

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    Quote Originally Posted by srs5694 View Post
    Out of curiosity, I once tried a mixture of Mountain Dew and sodium carbonate. No dice. As I recall, it actually cleared the film. I have no idea if it was working as a fixer or if it just ate away the emulsion. Probably the latter.
    I would guess that it's the latter as well.

    Anyway, there's nothing in the structure of caffeine that would suggest that it's redox-active (a necessary condition to be a good developing agent) as is.

  7. #17
    Ole
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    Quote Originally Posted by gainer View Post
    I haven't tried it, mostly because my brain has other needs for coffee, but I wonder why instant coffee is specified.
    ...
    When I drink coffee, I would rather wait on the coffee maker than drink the instant stuff, even Folger's.
    Maybe that's the reason... Coffee drinkers would rather drink their real coffee, and have finally found a use for the dreadful instant stuff. Non-coffee-drinkers, on the other hand, might as well buy the dreadful instant stuff, since they don't know the difference anyway.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #18
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    Since we drink wine and coffee rather than use them as developers, then we should use another of Grant Haists suggestions. Urine is a good developer, according to him. Perhaps it is due to all of the coffee and wine we drink.

    PE

  9. #19

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    So far over 800 compounds have been identified in coffee. Many of these may have developer capability if they are present in sufficient concentration. The principal chemicals appear to be caffeic acid and its esters. BTW, caffeic acid and caffeine are NOT structurally similar and caffeine has no developer properties.

    Just because a chemical is a reducing agent does not mean that it is a developing agent. For those interested I would refer them to a book on photochemistry which will discuss further restrictions on the type of reducing agent. The most recent is by Grant Haist but older books may still have a good explanation.

    Coffee is a far better drink than it is a developer.

  10. #20
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    If a reducing agent is too strong, it becomes a fogging agent.

    Examples include stannous chloride, hydrazine and t-butyl amine borane which have been used as fogging agents in reversal processes.

    Some just fog the emulsion, while others actually fog and reduce at the same time forming silver metal everywhere with no discrimination.

    PE

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