Oxidation By 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 experiment • Steps • Apply the piece of apples’ respective liquids. • Start timer for 1 hour. Take video of all the pieces of apples (Start of experiment, 0 Hours) • At every 1 hour interval, take video of all the pieces of apple and record how brown they are. • After 5 hours, take down the colour and video the pieces of apples as usual and stop the experiment. • Make a table that shows what I observed during the experiment. • Experiment • An Apple (Cut into 4 pieces) • Lemon Juice, Milk, Green Tea • A piece of cloth • 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. 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.
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 Acid Citric 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, Grapefruits, Oranges and Limes are very good sources of Citric Acid.
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 antioxidants. 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.
References http://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.rps.psu.edu/probing/antioxidants.html
Pictures http://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