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

Aim of Experiment

The aim of my experiment is to find out if there are any other liquids to prevent oxidation of fruit better than

those with Citric acid.

How this piece of information can help mankind

In restaurants, before chefs serve fruits, the fruits might get oxidized and spoil. Even if it doesn’t spoil it will not look presentable. Antioxidants will slow down the rate of oxidation. Many people apply Lemon Juice

(Citric Acid) to reduce the rate of oxidation.I hope to promote healthy eating and making people

realize the importance of Antioxidants.

Carrying out the experimentSteps1.Apply the piece of apples’ respective liquids.2.When done, place the pieces of apples on the piece of

cloth3.Start timer for 1 hour. Take video of all the pieces of apples

(Start of experiment, 0 Hours)4.At every 1 hour interval, take video of all the pieces of

apple and record how brown they are.5.After 5 hours, take down the colour and video the pieces of

apples as usual and stop the experiment.6.Make a table that shows what I observed during the

experiment.

Experiment7. 4 pieces of apples (1 Apple)8. 3 containers9. Lemon Juice, Milk, Green Tea10. A piece of cloth11. 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 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.

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 (Tocopherols, tocotrienols), found in Vegetable Oils.

- Carotenoids (Lycopene, carotenes, lutein), found in Fruits, Vegetables and Eggs.

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

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.

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

This is why many people take Vitamin C, Vitamin E, foods with Antioxidants. Actually, I think some of them don’t even know they are taking Antioxidants themselves!

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.)

There are lots of Polyphenol Antioxidants inside Blackberries, Blueberries and Cranberries.

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! It has a very high concentration of Citric Acid.)

Citric Acid is also used in Cosmetics and Detergent.Flavonoids can be found in Citrus Fruits, thus giving

it the antioxidant properties. Citric Acid also contains Vitamin C (Ascorbic Acid), which is also an antioxidant.

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

(Lemons and Limes have very high concentrations 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

Extremely Brown

Looks a little rotten

Looks very Rotten

Looks very rotten

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?Basically, it has nothing, absolutely nothing on it. So the oxygen in the air can interact with the substances in the apple easily.

Why is milk 3rd?Milk has no antioxidant properties.

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 Lemons’ high concentration of Citric Acid is also a factor. As the people say, the more the merrier!

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

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