CHEMISTRY PROJECT

Analysis of Vitamin C (Ascorbic Acid) in different types of fruits juices of the same brand

Group members: 1. Ysabel Deborah

2. Zephaniah Chong En Wei

3. Sarah a/p Ilangovan

Teacher advisor: Pn Betty Wong

Appreciation

We would like to express our heartfelt gratitude especially to:

1. Pn Betty Wong, our beloved teacher advisor for giving us a lot of guidance and advices.

Not only that, we will not forget the help she gave us in solving the problems we encountered

throughout the research.

2. The school computer lab, for following us to access the Internet with ease in order to

obtain the information that we were looking for. Besides that, we would also like to thank the

school library for providing us with a wide range of reading materials.

3. All parties that also succeeded this research.

Abstract

The goal of the analysis is to know the content of vitamin C in the four types of fruit juice, A

(Apple juice), B (Orange juice), C (Guava juice), D (Grape juice). The lower the value of pH,

the higher the content of vitamin c (ascorbic acid) in the labelled juices, A, B, C, D. The

method used to determine the content of vitamin C is by using a pen pH meter. From the

results, we concluded that the different types of fruit juice of the same brand do contain the

same content of vitamin C.

Introduction and background of research:

Vitamin C

Vitamin C is a water-soluble vitamin that is necessary for normal growth and development.

Leftover amounts of the vitamin leave the body through the urine.

Vitamin C is needed for the growth and repair of tissues in all parts of your body. It is used to

form an important protein used to make skin, tendons, ligaments, and blood vessels, heal

wounds and form scar tissue, and repair and maintain cartilage, bones, and teeth.

Vitamin C is a antioxidant. Antioxidants are nutrients that block some of the damage caused

by free radicals. Free radicals are made when your body breaks down food or when you are

exposed to tobacco smoke or radiation. The build up of free radicals over time promotes

aging process. Free radicals play a role in cancer, heart disease, and arthritis. Since the body

is not able to make vitamin C on its own and does not store vitamin C, therefore it is

important to include plenty of vitamin C-containing foods in your daily diet.

All fruits and vegetables contain some amount of vitamin c. Fruits with the highest sources of

vitamin c include citrus fruits and juices, such as orange, grapefruit, kiwi, mango, papaya,

pineapple, strawberries, raspberries, blueberries, cranberries and watermelon.

Vegetables with the highest sources of vitamin c include broccoli, brussels sprouts,

cauliflower, green and red peppers, spinach, cabbage, turnip greens, and other leafy greens,

white potatoes and tomatoes.

Too little vitamin c can lead to signs and symptoms of deficiency, including anaemia,

bleeding gums, decreased ability to fight infection, decreased wound-healing rate, dry and

splitting hair, easy bruising, gingivitis, nosebleeds, possible weight gain because of slowed

metabolism, rough, dry, scaly skin, swollen and painful joints, weakened tooth enamel. A

severe form of vitamin c deficiency is known as scurvy, which mainly affects older,

malnourished adults.

Source from: http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm

Date: 21/02/2013

Methodology

How to Use a Pen pH Meter

Instructions:

1. Pour approximately 3 oz. of buffer solution into a cup. Remove the cap on the

end of the pen. Turn on your pH pen. Immerse the probe end of the pen into the buffer

solution. Swirl the pen around in the solution to dislodge any air bubbles. Wait for the meter

to show a stable reading. Check the pH value on the reading. Adjust the reading according to

the pen's instructions so that the display reads 7.0.

2. Clean the pen by rinsing it under running water. Immerse the pen in your

sample to test its pH level. Swirl the pen around in the sample to dislodge any air bubbles and

ensure a more accurate reading. Wait for a stable reading to show on the pen's display.

3. Record the value on the pen's pH display with the pen and paper. Remove the

pH pen from the sample and turn it off. Wash the pen thoroughly in running water to avoid

cross-contamination and prevent incorrect readings. Replace the cap on the end of the pen to

prevent damage to the probe.

Source: http://www.ehow.com/how_7900217_use-pen-ph-meter.html

Date: 21/02/2013

How to Calibrate and Use a pH Meter

Steps

1 Rinse the pen's electrode, which is the glass probe at the end of the pen, by pouring

distilled water onto it from a squeeze bottle.

2. Gently blot the electrode dry with a soft tissue. Ensure that there is no water left on the

electrode.

3. Turn the pen on by clicking the "on" button found at the top of the pen.

4. Immerse the pen into the glass beaker containing the reference solution with a pH of 7.

5. Gently stir the pen in the solution while waiting for the reading to stabilize.

6. Use the screwdriver to turn the small screw in the hole in the back of the pen until the pen

reads precisely "7."

7. Remove the pen from the reference solution and rinse the electrode again with distilled

water. Wipe it again with a paper towel.

Source: http://www.ehow.com/how_5494207_calibrate-ph-pen.html

Date: 21/02/2013

Report

Topic: Analysis of vitamin c (ascorbic acid) in fruit juices

Problem statement: Do different fruit juices of the same brand contain the same content of

vitamin c?

Aim: To determine the content of vitamin c (ascorbic acid) in different types of fruits juices

Hypothesis: The lower the value of pH, the higher the content of vitamin c (ascorbic acid)in

the labelled juices, A, B, C, D

Instruments/Apparatus: pen type pH meter, four 250ml beakers, polystyrene cup, paper

towels

Materials: Different types of fruit juices of the same brand, buffer solution

Experimental design: The pH value of the different fruit juices from same brands is

measured to know the content of vitamin c (ascorbic acid) in each type of fruit juices

Procedure:

1. Four 250ml beakers are prepared and labelled A, B, C, D.

2. 200ml of the fruit juices of different flavours are poured into the following labelled

beakers.

3. 100ml of buffer solution is measured and poured into a polystyrene cup. The cap of the pen

type pH meter is removed and turned on. The probe end of the pen type pH meter is

immersed into the buffer solution.

4. The pen type pH meter is swirled in the buffer solution to prevent air bubbles and is left in

the solution for at least 30 seconds until it reads pH 7.

6. The pen type pH is rinsed under running water and excess liquid is dried with a paper

towel.

7. The pen type pH then is immersed into the fruit juice labelled A to obtain its pH value.

8. The pen type pH meter is swirled in the fruit juice to prevent air bubbles and is left in the

solution until a stable reading is displayed.

9. The value shown on the pen type pH meter is recorded in a table.

10. The steps 6 to 9 are repeated using the other sample of fruit juices in beaker B, C, and D.

Results:

pH

A(Apple juice)

B(Orange juice

C(Guava juice)

D(Grape juice)

Reading 1 3.1 3.1 3.2 3.3

Reading 2 3.1 3.0 3.2 3.3

Juices

Discussion

Ascorbic acid or commonly known by its household name vitamin C

are very important to us human beings. Some important roles this vitamin

plays in our body are as enzymatic cofactors, as an antioxidant, pro-

oxidant and as antihistamine. Most of us humans obtain our ascorbic acid

through fruits especially in the form of fruit juices be it natural fruit juices

or commercialised fruit juice. Natural fruit juices are believed to contain

more amounts of vitamin C compared to commercialised fruit juices.

Type of juice

Ammount of vitamin C per

100ml

Orange 132 mg

Grapefruit 120 mg

Apple 89 mg

Tangerine 85 mg

Lemon 46 mg

Pineapple 44 mg

Lime 30 mg

Passion Fruit 30 mg

Black berry juice 11 mg

Cranberry 9 mg

Source: http://nutritiondata.self.com/foods-009101000000000000000-4w.html?

Commercialised fruit juice companies have made a very large variety of

types of fruits juices. The fruit juices picked by us for our experiment are

apple juice (A), Orange juice (B), Guava juice (C) and white grape juice (D)

from the same brand (Marigold, Peel Fresh).

200ml of each type of juice was poured into four respective 250 ml

beakers.

The four beakers of juices were tested for their pH value using a pen

pH meter. Results were obtained and tabulated.

Before the testing began a buffer solution was used to calibrate the

pen type pH meter and to ensure the readings of the pen type pH meter is

accurate. We made sure that the pen type pH meter reading was 7 when

immersed into the solution.

The experiment was repeated twice and the readings were taken

twice with a different pH meters to obtain a more accurate reading.

Precaution were taken to ensure the accuracy of the reading by wash the

pen type pH meter in running water and dried with a paper towel before

taking the next reading of a different juice. The pen type pH meter was

swirled a few times in the fruit juices to avoid and air bubbles dislodged in

the fruit juice.

pH

A(Apple juice)

B(Orange juice

C(Guava juice)

D(Grape juice)

Reading 1 3.1 3.1 3.2 3.3

Reading 2 3.1 3.0 3.2 3.3

The data collected by the pen type pH meter was recorded and tabulated.

Form our observation of the nutritional information of the fruit juices on the back of the box,

our conclusion was also strengthened. We saw that all the vitamin C contents in the fruit

juice were the same (39mg) for juice A, B, C and D.Therefore we made a final conclusion

through both our experiment and our observation that the different types of fruit juice of the

same brand do contain the same content of vitamin C. The vitamin C content is not affected

by the type of fruit juice if the fruit juice came from the same brand.

Juices

Conclusion

We conducted an experiment to attain answers for our problem

statement ‘Do different fruit juices of the same brand contain the same content of vitamin

c?’ and to achieve our aim ‘To determine the content of vitamin c (ascorbic acid) in different

types of fruits juices’. From the experiment the results obtained were recorded and tabulated.

A conclusion was made based on the results obtained.

From our experiment, we concluded that the different types of fruit juice of the same

brand do contain the same content of vitamin C. This is because from our experiment the

acidity of all our fruit juices are almost the all the same with only a slight pH difference of

0.2. From our hypothesis we know that ‘The lower the value of pH, the higher the content of

vitamin c (ascorbic acid )in the labelled juices, A, B, C, D’. Therefore we finally concluded

that all of the fruit juice A, B, C, D, had the same vitamin C content due to the insignificant

difference in the pH.

Bibliography

1. http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm

2. http://www.ehow.com/how_7900217_use-pen-ph-meter.html

3. http://www.ehow.com/how_5494207_calibrate-ph-pen.html

4. http://nutritiondata.self.com/foods-009101000000000000000-4w.html