OxidationBy Ace Ang, 5 Victorious, Rosyth School, 2010.

Aim of ExperimentI hope to promote healthy eating and making

people realize the importance of Antioxidants.

How can this information help mankind?

A cut piece of fruit that is oxidized will lose nutrients. Thus, when we eat it, we won’t gain the full benefits of eating the apple. In addition, the cut piece of fruit might spoil too. Oxidized foods may not be harmful to eat sometimes, but the cut piece of fruit turning brown has spoiled the image. (I would not want to eat such a piece of fruit)

The experiment will be to physically observe how antioxidants work, and how they can help in preserving the fruit.

Carrying out the experiment

Steps

1.Apply the different kinds of liquids on the surface of the cut apples.

2.Start timer for 1 hour. Take video of all the pieces of apples (Start of experiment, 0 Hours)

3.At every 1 hour interval, take video of all the pieces of apple and record how brown they are.

4.After 5 hours, repeat step 3 and stop experiment.

5.Make a table that shows what I observed during the experiment.

Experiment

6.An Apple (Cut into 4 pieces)7.Lemon Juice, Milk, Green Tea8.A piece of cloth9.Timer

What is Oxidation?Oxidation is the interaction between oxygen

molecules and the different substances they may come into contact with.

Oxidation is the loss of at least one electron when two or more substances interact.

Oxidation can be observed all around us.For example, you may observe a fresh piece of

cut fruit turning brown over time. That is oxidation.At other times, you may observe a metallic

object having brown spots on them. That is rusting, scientifically called, Oxidation.

Actually, some things we eat oxidize too.

For example, let’s say I bought a bag of mozzarella cheese and left it in the fridge, and a few days later I take out the bag of mozzarella cheese and found the cheese having a darker colour.

A cut piece of apple left untouched will turn brown over time, showing the process of oxidation too.

How do Antioxidants Work?

The process of Oxidation creates Free Radicals. Free Radicals are atoms, molecules or ions with one or more unpaired electrons. These Free Radicals can start chain reactions and damage cells.

The production of Free Radicals at the cellular level is believed to be involved in the cause of Cancers.

Free Radicals can donate its odd electron to another molecule, and can also take an electron from a nearby molecule.

Antioxidants help by preventing oxidation, by being oxidized themselves. They terminate the chain reactions by removing the Radical Intermediates, and inhibit other Oxidation reactions.

Antioxidants can work in and out of the body. If I were to apply some Lemon Juice onto a cut piece of apple, the rate of oxidation would be reduced a lot, because the Antioxidant properties of the Flavonoids and Vitamin C (Ascorbic Acid) in the Citric Acid is slowing down the rate of oxidation. The same thing happens inside your body, except at the cellular level. The Antioxidants in your body can neutralize the Free Radicals by either providing the extra electron needed to make the pair, or by breaking down the Free Radical molecule.

What is an Antioxidant?

An Antioxidant is a molecule that is able to prevent the oxidation of other molecules.

There are many kinds of Antioxidants.

There are…

- Polyphenol Antioxidants, commonly found in Tea, Coffee, Soy, Olive Oil and Fruits such as Citrus Fruits and Grapes.

- Vitamin C (Ascorbic Acid), found in Fresh Fruits and Vegetables.

- Vitamin E, found in Vegetable Oils.

- Carotenoids, found in Fruits, Vegetables and Eggs.

For my experiment, I will be using Polyphenol Antioxidants (Green Tea) and Vitamin C, or, Ascorbic Acid (Lemon) as Antioxidants, and Milk. I will also make use of the surrounding air.

Polyphenol Antioxidants

Polyphenol Antioxidants are antioxidants containing Polyphenol substructures.

Flavonoids are also Polyphenol Antioxidants. They are found naturally in plants.

Some good sources of flavonoids include all Citric Fruits, Tea, Red Wine.

Grape Skin contains many Polyphenols and flavonoids.

Some foods that contain Polyphenol Antioxidants include…- Green Tea- Coffee- Olive Oil- Soy- Fruits (Citrus Fruits, Grapes, etc.)- Berries (Blackberries, blueberries, cranberries, etc.)

Blackberries, Blueberries and Cranberries contain Polyphenol Antioxidants.

Citric AcidCitric Acid, found in Citrus Fruits, is a weak

organic acid. A preservative used to add an acidic or sour taste to foods and soft drinks.

Citric Acid is used by many people as an antioxidant to preserve fruits, by simply applying the Citric Acid on the cut fruit’s surface. (Many people used Lemon Juice as lemons have very high concentrations of Citric Acid.)

Citric Acid is also used in Cosmetics and Detergent.

Citric Acid contains Flavonoids and Vitamin C (Ascorbic Acid), thus giving it its antioxidant properties.

Lemons, Oranges and Limes are very good sources of Citric Acid.

Conclusion (Part 1) – The Table

Intervals of hours/Type of Liquid

Used

1 Hour Interval

2 Hour Interval

3 Hour Interval

4 Hour Interval

5 Hour Interval

Air Very Brown

Very Brown

Very Brown

Extremely Brown

Extremely Brown

Milk A little brown

A little brown

Brown Brown Brown

Green Tea

No Change A little brown

A little brown

A little brown

A little brown

Lemon Juice

No Change No Change No Change No change No change

Conclusion (Part 2) – Why?

Why is the apple without anything applied to it the brownest?There’s nothing applied, so it is the most exposed. The oxygen in the air can interact with the substances in the apple easily.

Why is milk 3rd?Milk has no antioxidants, but it prevents some oxygen from reaching the surface of the cut piece of apple, thus slowing down the rate of oxidation by a bit.

Why is Green Tea 2nd?Green Tea has Polyphenolic Antioxidants.

Why is Lemon Juice 1st?Lemon Juice has Citric Acid, which contains Polyphenolic Antioxidants and Vitamin C (Ascorbic Acid).Also, the high concentration of Citric Acid found in the lemon is also a factor.

Referenceshttp://en.wikipedia.org/wiki/Citric_acid

http://en.wikipedia.org/wiki/Antioxidant

http://www.wisegeek.com/what-is-oxidation.htm

http://en.wikipedia.org/wiki/Radical_%28chemistry%29

http://en.wikipedia.org/wiki/Polyphenol_antioxidant

http://www.wisegeek.com/what-are-flavonoids.htm

http://en.wikipedia.org/wiki/Flavonoids

http://www.medicinalfoodnews.com/vol01/issue5/anti

http://www.wisegeek.com/what-is-rust.htm

Pictureshttp://www.solarnavigator.net/solar_cola/cola_images/Oranges_Ambersweet.jpg

http://www.slowfoodusa.org/images/ark_products/ark-prod-meyer_lemon.jpg

http://malkup.com/slike/Blackberry.jpg

http://upload.wikimedia.org/wikipedia/commons/d/d8/Grapefruit_Schnitt_2008-3-3.JPG

http://www.stargazerperennials.com/images/blueberries.jpg

http://www.pacifichealth.info/images/cranberries.jpg