Experiment 4: Vitamin C

TITLE

Experiment on Vitamin C

OBJECTIVES

1. To measure the amount of Vitamin C content in many different types of food.

2. To measure the amount of Vitamin C content in types of food in different conditions of the food        

    is served.

ABSTRACT

This experiment is carried on in order to measure the amount of Vitamin C content in several types of food. This experiment also been carried out by measuring Vitamin C content in several types of food condition for example, when the food is steamed, boiled and when the food is served fresh. Titration method is used when, iodine is used to test the Vitamin c content where, the volume of iodine used to titrate the Vitamin C sample from foods been taken. The volume is taken just after, the vitamin C sample turns to blue black colour and not further turns to its original colour. In this experiment, Red Apple sample of food is used. This experiment been carried out in three different conditions of red apple that are in fresh, steam and also boil condition. The result shows fresh sample has highest content of Vitamin C, followed by steamed red apple sample and the lowest content of Vitamin C is sample of red apple when the sample is been boiled. This experiment shows that, fresh red apple juice has higher level of Vitamin C compared to processed red apple juice.

INTRODUCTION

Vitamins are organic compounds that have important biological functions. For instance, in humans they enable a variety of enzymes in the body to function. The human body cannot synthesize vitamin molecules, so they must be obtained in the diet. If a particular vitamin is lacking in the diet, a deficiency disease will result. Vitamin C, also called ascorbic acid is a water-soluble vitamin that occurs naturally in many fruits and vegetables, such as citrus fruits, green peppers, tomatoes, and parsley. It is not stable to heat, so cooking fruits and vegetables destroys much of their vitamin C content. It is also easily oxidized (converted to a non-useful form) by certain compounds, such as oxygen in the air. Therefore, the vitamin C content in an orange will be reduced if the orange has been cut in half and left exposed to the air for a period of time. Although fruit juice is a good source of vitamin C, it is not the healthiest way to obtain the vitamin, since fruit juices are very high in sugar/simple carbohydrates. Starch-iodine is used because Vitamin c can react with iodine. When iodine is added, it will first react with the ascorbic acid in the food sample, producing a colorless product (dehydroascorbic acid). When the ascorbic acid runs out, the iodine will react with the starch in the food sample. At this point, participants will be able to recognize a highly visible color change. This color change is the endpoint of the reaction. Therefore, the more iodine added, the more Vitamin C the food sample contained.

PROCEDURE

Part A: Measuring Vitamin C Using Starch-Iodine Test

Preparing vitamin C extract:

                                 i.            The food material is chopped into small pieces and is placed into blender.

                               ii.            100 mL of distilled water is added to the blender.

                              iii.            The material is blended using the highest speed.

                             iv.            The ground extract is strained.

                               v.            30 mL of strained extract is measured into a 250 mL Erlenmeyer flask.

1.       Comparing cooked food and raw food’s vitamin C:

                                 i.            The raw, steamed and boiled food are used to determine the amount vitamin C.

Part B:

Application: Magic Writing

RESULT

Part A: Measuring Vitamin C Using Starch-iodine Test

CALCULATION

Standard:

1 mg/ml ascorbic acid   = 72.5 ml iodine

Fresh Apple:

Fresh :-       26.20 ml iodine

Vitamin C in 30 g fresh apple = 26.20 ml/72.5 ml

                                            = 0.361 mg/ml of Vitamin C

Vitamin C in 100 g fresh apple = (100 g/30 g) x 0.361 mg/ml

                                            = 1.203 mg/ml of Vitamin C

Steamed Apple :

Steamed :-       22.45 ml iodine

Vitamin C in 30 g steamed apple = 22.45 ml/72.5 ml

                                                  = 0.310 mg/ml of Vitamin C

Vitamin C in 100 g steamed apple = (100 g/30 g) x 0.310 mg/ml

                                                    = 1.033 mg/ml of Vitamin C

Boiled Apple :

Boiled :-       20.15 ml iodine

Vitamin C in 30 g boiled apple = 20.15 ml/72.5 ml

                                               = 0.278 mg/ml of Vitamin C

Vitamin C in 100 g boiled apple = (100 g/30 g) x 0.278 mg/ml

                                                    = 0.927 mg/ml of Vitamin C

DISCUSSION

Part A: 

Measuring Vitamin C Using Starch-iodine Test

(I) On Fresh, Raw Apple

Based on the experiment that had been carry out, the result show that the amount of vitamin C in fresh apple is higher than in apple that had been boiled and steamed.

There are dietary fibre content skins and core of apples. About 10% of an apple is made up of carbohydrate and 4% of an apple is made up from a variety of vitamins and minerals and the rest of the apple, more than 80%, is water. For a medium-sized eating apple contains about 40 calories while one kilogram of fresh apples provides approximately 500 kcal of energy. Without the peel and core of apples from the diet halves the amount of vitamin C and dietary fiber consumed but makes very little difference to the sugar intake.

Consumption of vitamin C-rich foods in their fresh or raw form is the best way to maximize vitamin C intake. Furthermore, vitamin C is highly sensitive to air, water, and temperature. About 25% of the vitamin C in vegetables can be lost simply by blanching which is boiling or steaming the food for a few minutes. This same degree of loss occurs in the freezing of vegetables and fruits. By cooking vegetables and fruits for longer periods of time within 10-20 minutes can result in a loss of over one half the total vitamin C content. That’s why fresh apple have high amount of vitamin c than steam and boiled apple. 

(II) On Steamed Apple

While, for steam apple we had steamed it in oven for 20 minutes under 55⁰C. So, the results of vitamin C that we had obtained from the experiment for 1mL of juice was 0.31g/ml. The vitamin C content of food may be reduced by prolonged storage and by cooking. But by steaming or microwaving may lessen cooking losses. For steam fruit, most of the vitamin C retain in the fruit. Other than eating it raw, the fruit can be steam to avoid losing too much vitamin C.Fortunately, many of the best food sources of vitamin C, such as fruits and vegetables, are usually eaten raw.

(III) On Boiled, Cooked Apple

When boiling is applied to the fruit, the high temperature affects the amount of vitamin C content. It is

because vitamin C, which is sensitive to heat, is easily destroyed by excessive heat. The concentration of

vitamin C is decreased after cooking. As vitamin C is a type of water soluble, boiling may cause great loss of 

vitamin C not only thermal degradation, but also by leaching into surrounding water. Boiling causes more loss 

of vitamin C than steaming.            

In order to prepare the food in the most nutritious way, it is suggested to eat the fruits and vegetables raw 

because eating raw keeps the vitamins intact. For the exceptions, the food may undergo steaming before 

eating. The more water kept in the fruits or vegetables, the better for the nutrition. 

Part B:

Application: Magic Writing

After adding the iodine solution, the writing appears glowing. However this condition only last for awhile as we are forgetting to dilute the iodine solution. This condition happened due to the reaction between iodine and the vitamin C (from the lemon juice). When this reaction happens, both the iodine and the vitamin C turned into different chemicals called dehydroascorbic acid. As the amount of iodine is more than the amount of vitamin C that was on the paper, all of the vitamin C is destroyed and the iodine remains. 

CONCLUSION

Fresh apple retains the most vitamin C. It is followed by steamed apple. The vitamin C in boiled apple is 

damaged.

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