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  1. #1

    Join Date
    Nov 2004
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    1,143

    Developer from red grape juice

    The phenolic groups in red grape juice are mainly Anthocyanins, marked with 1 in the table:
    http://jn.nutrition.org/content/136/...expansion.html
    Adding up,the total Anthocyanin concentration is 0.234 m-mol/L,for MW=450 this is 0.105g/L
    For comparison the concentration of pyrogallol in 1:100 PMK Pyro is 0.5g/L
    The Anthocyanins are subject to hydrolysis at high pH:
    http://www.demochem.de/p26_anth-e.htm

    GJ-1
    Red Grape Juice pH 3.7....................600ml
    Sodium Hydroxide...............................3g
    Phenidone......................................... 0.2g
    pH =10.9

    HP5 at EI=200 was developed in GJ-1 60min 20C, ag 10s every 2min.
    The negatives were underdeveloped but printable.
    One negative was bleached in 100g/L ferricyanide+bromide and fixed.
    A very faint relief image caused by the tanning of the gelatin by Anthocyanin or derivatives is shown in the attachment.(It is possible to provide a much better image from unbleached negative).
    Anthocyanins are present at low concentration and may be hydrolysed but produce detectable tanning.
    Other red/purple berries contain Anthocyanins, as a curiosity it may be possible to make staining developers from them.
    Thanks for comment.
    Attached Thumbnails Attached Thumbnails grape juice stain image.jpg  

  2. #2

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
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    Quote Originally Posted by Alan Johnson View Post
    Anthocyanins are present at low concentration and may be hydrolysed but produce detectable tanning.
    Other red/purple berries contain Anthocyanins, as a curiosity it may be possible to make staining developers from them.
    I enjoy reading about your experiments in fundamental research. Thanks for doing this. Last month was cabbage, wasn't it? Or was it Quercetin?
    Anyway, you spent an hour agitating that tank every other minute, having no idea if you'd get anything.
    That's the patience a good researcher needs.

    Mark Overton



 

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