Why did the solution turn green?

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Both citrulline and arginine are nitrogen-rich, basic amino acids. A basic acid sounds confusing, but that's the way it is.

The colour change indicates a change in the pH of the solution (the tea mix).

The pH indicator that changes the colour is in the hibiscus flower and belongs to the class of the anthocyanes.

Under acidic conditions, the dye exists as a deeply-red flavylium cation. At a slightly higher pH, the dye is reversibly converted to a colourless form. Here, the colour of the mixture is determined by the other ingredients. When more base (read: more amino acid) comes to action, further colour changes are conceivable and the double deprotonated form of some anthocyanes are known to be bluish-green.

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Jeff Gruskin
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Jeff Gruskin

Updated on August 01, 2022

Comments

  • Jeff Gruskin
    Jeff Gruskin over 1 year

    I mixed L Arginine with l Citrulline in Hibiscus and green tea water which was red in color. Once the red liquid hit the mix of powdered Aminoacids the solution changed green. Can someone tell me why? Thanks so much for any info!

  • Jeff Gruskin
    Jeff Gruskin over 8 years
    Dear Klaus,thank you so much for answering my question. So does this mean that the mixture created is now more acidic? Also since I am drinking this do you see any problems or should I just drink the Amino acids with water? Thank you so very much,Jeff
  • Klaus-Dieter Warzecha
    Klaus-Dieter Warzecha over 8 years
    Jeff, actually it should be just the opposite: the amino acids make the tea is more alkaline. Yes, alkaline (basic) amino acids are confusing, I'm a bit reluctant to answer the medical part oft the question, that's not really my field of work. but since the amino acids are a food supplement, I'd try to drink the with water and check if the taste of the tea is better then. Btw, if you think that the answer was helpful, you might have to accept it. Please have a look at this for the background.