It is kind of funny how ideas come into our minds. The other day while we were getting lunch ready, my daughter commented that the slices of apple were already starting to turn brown - we had just cut them. Click, a lightbulb went off. What if we did a simple apple science experiment? I have heard many theories of ways to stop or slow the browning of apple slices...which method works the best? My daughter and I got straight down to work on our browning apples experiment.
Apple Science Experiment: Apple Browning Experiment
We came up with 4 different theories to test. First, we had a plate with sliced apples with nothing done to them. Second, were our slices of apple that had been sprinkled with lemon juice. Third, we placed apple slices in an air tight container. Finally, we sliced and entire apple and wrapped it with an elastic - this is a new method that I have seen floating around the internet recently.
We started a stop watch and kept our eyes on our apple slices...and we waited.
The plain sliced apples started to brown immediately.
The apple slices in the air tight container started to brown after 5 minutes.
The elastic wrapped apple started to brown after 23 minutes.
The lemon coated apple slices stayed white the longest...in fact they lasted so long that we ended up eating them before they turned brown...a few hours after we set them out on the counter. Hands down the lemon juice worked the best. The next phase of the experiment was to see if the lemon juice changed the flavour of the apple slices. Happily my daughter reported that while she could taste the lemon, it was actually nice. 
So, why does the lemon juice work? It has to do with a chemical reaction called oxidation. The ascorbic acid (vitamin C) in the lemon juice creates a barrier between the apple slice and oxygen in the air. Without the acid, the enzymes in the exposed apple slices would react with oxygen (oxidation) and start turning the apple brown. The lemon juice barrier protects the apple enzymes. That's the basic version of what is going on, chemically in our experiment. I am always looking for ways to have fun with science. This experiment was a great way to engage my daughter in a fun science experiment in our kitchen.
Science Kiddo says
I love how scientific you made this simple activity! We always use lemon juice on our apples, too, and we carry them around with us all day sometimes and they are still yummy to eat!
Thanks so much for sharing your fun experiment @ Saturday Science! I have it pinned and scheduled to share on Facebook and Twitter.