Browning Apples

[LMH]

My kindergartener & I are working on her first science fair project. She (we) are trying to determine how to keep apples from turning brown after they are peeled & cut. I know that lemon juice will slow down this process, but in the past regular 7up has always worked for me. We have repeated the experiment 3 separate times with 3 different apples. The first 2 apples were used right out of the refrigerator, the 3rd one was left on the counter 24 hours away from a window to it would be at room temperature before conducting the experiment. We dipped one in regular 7up, diet 7up, water & milk. Of course one group was not dipped in anything for the control group. The problem is each time NONE of the apples turned brown not even the one that was left "undipped" for the control group. I used an apple slicer the first time and 2 different knives the next 2 times. I didn't think this would have anything to do with it but I wasn't taking any chances. Please help - LMH

[MelissaB]

What kind of apples are you using? I think some varieties of apples are more likely to turn brown faster--perhaps you could use them? I would personally use red delicious, based on my past experience.

The other question is, how long are you waiting? What is happening to the apples if they are not browning? Are they getting moldy first?

[LMH]

I used yellow delicious, honey crisp, & jonathon apples. They are staying "apple color" and looking a bit withered after 3 hours. I left them out over night but they just looked a bit more withered not brown. I don't think it's too cold in my house I keep it at 73 degrees F.

[deleted-139256]

I'm not entirely sure which apple variety will display the greatest color change. I however do know that oxidation is the primary source behind the browning process.
I quickly researched this topic and found a link that might helpful: http://chemistry.about.com/od/chemistry ... plefaq.htm

From what I gathered using a rougher coarser knife will bruise the apple more and expose more of the phenols in the apple that have the potential to turn red when exposed oxygen. Also you should probably ensure there isn't too much of the substance you are dipping the apples in on the surface(it may be forming a sort of film which could preventing oxygen from reaching the iron phenols. Changing the pH is what this article suggests ultimately hinders the reaction. Swabbing a little bit of substance may work better. As you probably know sodas will be acidicd, water neutral, and milk basic.

Also just based on my knowledge of enzymes there is usually some optimum temperature at which the catalyze a reaction the fastest. Below this temperature(like in a fridge) biochemical processes slow down. Far above this temperature enzymes begin to denature(break down). Your 73 degrees may be a bit cold for this. Even increasing the temperature 10-15 degrees may yield noticeable results.

Hope this helps

Feel free to post any questions you may have.

phi-unit

[deleted-342380]

R u picking apples in there prime?? Try just randomly chosen apples from Walmart or ones that are not the " best" GOOD LUCK!!!!!