Experiment: Vitamin C Levels

Have you ever wondered which fruit or vegetable contained the most vitamin C and is essential for good health? My experiment will consist of three different vitamin C tests. The main experiment will test the amount of vitamin C content in fourteen different fruits and vegetables and the second one will test the vitamin C change in orange and tomato juices when it is boiled. The last experiment is the vitamin C change in orange juices with several different storages such as in the refrigerator. Results may differ depending on the temperature and air. 

Purpose

The purpose of my experiment is to compare vitamin C concentration in various fruits and vegetables. I’ll also test how heat and temperature affects the decrease of vitamin C in certain fruits and vegetables. This project outlines how the amount of ascorbic acid in juice can be measured by a simple analytical technique (titration); this technique relies on the ability of the ascorbic acid to be oxidized by an oxidizing agent such as iodine. My project also compares the amounts of vitamin C in various juices. You can determine how much ascorbic acid remains if a juice container has been exposed to air, refrigerated and left at room temperature.

Another purpose is to determine the amount of iodine needed to react with a standard solution (carefully measured quantity) of vitamin C. When the results of the food with the most vitamin C are determined as well as how other foods differ in concentration of  vitamin C, you will know how healthy  certain fruits and vegetables are.

Vitamin C is an important anti-oxidant that helps protect against cancers, heart diseases, stress; it is part of cellular chemistry that provides energy and for making collagen protein involved in the building and health of cartilage, joints, skin, and blood vessels. Vitamin C helps maintaining a healthy immune system, it aids in neutralizing pollutants, it is needed for antibody production, it acts to increase the absorption of the nutrients (iron) and thins the blood. So that is why vitamin C is important for our daily lives. Mainly this project is about chemistry and nutrition.

Materials 

 Here are the supplies and resources you will need to conduct this experiment accurately.

• Starch      
• Pure water  
• Hot plate
• 4 medium jars with lids
• Small bowl
• 10ml syringe
• 0.1M iodine solution
• 2 eyedroppers
• 30ml measuring cup
• 150ml glass cup
• 500ml glass cup
• 20mg vitamin C powder
• Stirrer
• Hammer
• Marking pen and paper
• Orange juice
• 10ml of juice from as many different kinds of fruits and vegetables as possible

Method

Vitamin C is an ascorbic acid that consists of many biological functions. This important vitamin is not produced by your body but obtained from fruits and vegetables. It’s also needed for a healthy body. It can cure diseases such as cancer or repair tissues.

Starches are also carbohydrates. They are large complex molecules made of sugar molecules. Starch reacts with iodine to give a dark blue complex compound. Only starch among the carbohydrates shows this chemical reaction, so you can use iodine to test for presence of starch in foods.

1. Add about 5ml of water to 1g of starch in a cup. Add the water slowly, using a spatula to rub it into starch until you have smooth paste. Next add this starch paste to 100 ml of boiling water slowly and with a constant stirring. You should end up with a milky suspension without any lumps in it.
2. Dissolve 20mg vitamin C powder in 10 ml of water. This solution will provide you with a standard against which you can compare other solutions. You know how much vitamin C is in this standard solution: 20mg.
3. 10ml of the standard vitamin C solution with a vitamin C powder adds 1ml of starch solution.  As long as vitamin C is present, the iodine will react with it. As soon as the vitamin C is all gone, the next drop of iodine will react with starch, forming the characteristic dark blue which you are familiar with. Quickly count the drops of iodine solution needed to react with 20mg of vitamin C. Remember the more drops the more vitamin C.
4. Finally continue your test on other fruits and vegetables. In the end when you detect the vitamin C, bash a fruit with a hammer in a small bowl. Once the juice has filled the bowl insert the syringe into the bowl and fill it up to 10ml. After that, squeeze the juice into a glass cup. Add 1ml of starch solution into the cup and mix it. Use the eyedropper to place as many iodine drops as you can until a dark blue color appears. Record your results. You may want to compare frozen and canned juices or natural juice. Include how temperature affects the amount of vitamin C by boiling. Does storage orange juice in an open container affect the vitamin C content?
5. You can find the amount of vitamin C in the sample by comparing the number of drops of iodine needed in the test samples ( y drops in the formula below) compared to the number of drops needed for the standard solution (x drops in the formula below).

y drops/? mg vitamin C = x drops/ 20 mg vitamin C

or ?mg vitamin C = y drops x 20mg vitamin C/ x drops