The apple and ascorbic acid demonstration

we I’m sure we’ve all seen it. Someone puts the vitamin c (LAA) on a cut apple and leaves it out to prove it protects from oxidation. Is this not the low pH and reduction happening? Would the presence of LAA even be necessary?
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  • PerryPerry Administrator, Professional Chemist
    First, it's helpful to understand why apples turn brown in the first place. Basically, enzymes (polyphenol oxidase - PPO) oxidize phenolic compounds in the apple which then react with amino acids and proteins to make a brown color.

    PPO has a pH range at which it works optimally - pH 5.0 - 7.0. Below pH 3.0 it is inactivated. So, anything that is going to reduce the pH of the surface of the apple will significantly reduce the browning reaction. 

    LAA can work but so can citric acid, hydrochloric acid, acetic acid, glutathione, etc. It is a demonstration that can be easily fooled. Really, it is less a demonstration of the activity of the LAA and more a demonstration of the pH of the skin cream.
  • Perry said:
    First, it's helpful to understand why apples turn brown in the first place. Basically, enzymes (polyphenol oxidase - PPO) oxidize phenolic compounds in the apple which then react with amino acids and proteins to make a brown color.

    PPO has a pH range at which it works optimally - pH 5.0 - 7.0. Below pH 3.0 it is inactivated. So, anything that is going to reduce the pH of the surface of the apple will significantly reduce the browning reaction. 

    LAA can work but so can citric acid, hydrochloric acid, acetic acid, glutathione, etc. It is a demonstration that can be easily fooled. Really, it is less a demonstration of the activity of the LAA and more a demonstration of the pH of the skin cream.
    Boom! Thank you! The videos drive me bonkers. Also I’m not an apple. 
  • So you are a microsoft?

    With hardcore marketing and enough time to create a cult, I could make people believe that you actually are an apple, the resurrection of the sin of Adam and Eve, if you want.

    Well joking aside, have you come to term with what you comfortable calling yourself?
    As much as I love cosmetic ninja but please don't go with it definitely. 
  • Pattsi said:
    So you are a microsoft?

    With hardcore marketing and enough time to create a cult, I could make people believe that you actually are an apple, the resurrection of the sin of Adam and Eve, if you want.

    Well joking aside, have you come to term with what you comfortable calling yourself?
    As much as I love cosmetic ninja but please don't go with it definitely. 
    Well now I have to use it forever 
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