Apples and enzymes

[Stiganator]

I can't think of who else would know how to explain this? When an apple browns tyrosianse aka polyphenoloxidase reacts oxygen and tyrosine into melanin or something? But I can't find any structures so I can't fully explain the reactions can anyone help and enlighten me on the whole process?

 

[Descend492]

I have no idea, but I think lemon juice (not sure if it's lemon juice or not) makes the reaction reverse, and turns the apple white again.

 

[Mark R]

These reactions are heterogeneous, with multiple different polyphenol substrates and intermediates. The classic reaction is that where catechol (1,2-dihydroxybenzene) is oxidised to 1,2-benzoquinone (ketone moieties occupying the 1 and 2 positions of the benzene ring).

The resulting indoles and quinones readily polymerise to form melanins.

 

[zsouthboy]

Originally posted by: Mark R
These reactions are heterogeneous, with multiple different polyphenol substrates and intermediates. The classic reaction is that where catechol (1,2-dihydroxybenzene) is oxidised to 1,2-benzoquinone (ketone moieties occupying the 1 and 2 positions of the benzene ring).

The resulting indoles and quinones readily polymerise to form melanins.

wow, i believe that is the most un-understandable thing i have ever read in HT. i hope chemistry teaches me some more this year(junior in high school )

 

[Mark R]

wow, i believe that is the most un-understandable thing i have ever read in HT. i hope chemistry teaches me some more this year(junior in high school )

Oh. I thought I explained it quite well.

 

[JHutch]

If you've taken organic chemistry, it's vaguely understandable...

If you actively still work with words like "ketone", "polymerise" and "moieties," it probably makes perfect sense. Of course, it also means you are no longer just a geek... You're an uber-geek!

JHutch