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