What you need:
• Baking sheet or wax paper
• Labeling tape
• Pen or marker
• Tongs
• Bowl
• Knife
• Lemon juice
• Vinegar
• Water
• Salty water
• Dishsoap
• Oil
• Apple

What you do:
• Use the tape to create labels for each type of liquid you will test.
• Place your labels on the baking sheet or wax paper.
• Cut the apple into slices at least 1-cm thick.
• Set out a slice of each food item on the baking sheet or was paper under the heading “Control.”
• Fill the bowl with enough liquid to fully submerge each sample.
• Dip a slice into the liquid with tongs. Be sure to cover the whole slice! Let the extra liquid drip off before placing it under the correct label on the baking sheet or wax paper.
• Rinse out the bowl and repeat until you have made samples with each liquid.
• Record all your observations, taking note of the time.

NT.:  The food’s skin protects the inside “meat” of the fruit or vegetable from damage and debris. When a fruit or vegetable is dropped and the skin is poked or broken, the food often goes bad faster. The reason fruits and some vegetables go brown when they are cut is because the part containing the oxygen-reactive enzyme is exposed. There is then a lot of surface area for the air to come in contact with the food. For the most part, brown fruits and vegetables still taste fine, they just do not look very appetizing.

Acids prevent browning because they react with the oxygen that comes into contact with the surface of the sample. Once all the acid (or whatever else is covering the surface) has reacted with the oxygen or the acid has degraded or washed off, then the sample will start to brown again. Stronger acids, like lemon juice, can even denature the enzyme. This means that the enzyme can no longer perform its original function because of its environment.