The Vitamin c Content of Fruit Juice

BIOLOGY LAB REPORT

TITLE : THE VITAMIN C CONTENT OF FRUIT JUICE

PREPARED BY :

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OBJECTIVE

To investigate the Vitamin C content in fruit juices based on standard curve obtained.

Introduction(1)

Functions of vitamin C(4)

Vitamin C or known as L-ascorbate is an essential nutrient for humans and certain other animal

species. In living organisms ascorbate which is an ion of ascorbic acid acts as an antioxidant by

protecting the body against oxidative stress. (1) It is also a cofactor in at least eight enzymatic

reactions . Vitamin C also aids in detoxification and in improving ferum absorption. Other that

that, vitamin C also ensure the maintenance of cartilage, bone, denin and healthy blood vessel..

Humans and rodents cannot synthesis vitamin C but most of other animals have the ability to

synthesis vitamin C. (1)Thus intake of vitamin C ensure healthy lifestyle. Since vitamin C is a

water soluble vitamin, since it cannot be stored in human body. The uses and recommended

daily intake of vitamin C are matters of ongoing debate, with RDI ranging from 45 to 95 mg/day.

(1) Vitamin C is most present in the liver and least present in the muscle. Since muscle provides

the majority of meat consumed in the western human diet, animal products are not a reliable

source of the vitamin. Vitamin C is present in mother's milk but, not present in raw cow's

milk. All excess vitamin C is disposed of through the urinary system.

Sources of vitamin C(4)

Apricots, apples, banana, blackberries, cherries, kiwi, grapes, lemon, lime ,mango, lychee,

melon, orange, peach, pear, pineapple, plum, pumpkin, raspberries, strawberry, tomato and

watermelon are some of fruits that contain high content of vitamin C. In the other hand,

vegetables like artichoke, asparagus, avocado, broccoli, cabbage, corn, paprika, mushroom and

spinach have vast content of vitamin C.

Deficiency symptoms for vitamin C (2)

Deficiency of vitamin C(4)

Full-blown symptoms of the vitamin C deficiency disease called scurvy - including bleeding

gums and skin discoloration due to ruptured blood vessels. (2) Poor wound healing and can be a

symptom of vitamin C deficiency. (2) Weak immune function, including susceptibility to colds and

other infections, can also be a telltale sign of vitamin C deficiency. (2) Since the lining of our

respiratory tract also depend heavily on vitamin C for protection, respiratory infection and other

lung-related conditions can also be symptomatic of vitamin C deficiency. (2) Poor collagen

formation, scaly skin, degeneration of blood vessels, muscles and cartilage and also epithelial

haemorrhages also is very visible effects that shows deficiency of vitamin C.

Precautions regarding vitamin C intake.(3)

Hemochromatosis(4)

Because of the potential for side effects and interactions with medications, you should take

dietary supplements only under the supervision of a knowledgeable health care provider.

Vitamin C supplements have a diuretic effect, so drink plenty of fluids when taking them.

People sensitive to corn should look for alternative sources, such as sago palm. Vitamin

C increases the amount of iron absorbed from foods.

People with hemochromatosis (an inherited condition where too much iron builds up in

the body) should not take vitamin C supplements.

High doses of vitamin C can cause diarrhea, gas, or stomach upset. People with kidney

problems should talk to their doctor before taking vitamin C.

People who smoke or use nicotine patches may need more vitamin C because nicotine

decreases the effectiveness of vitamin C in the body.

Infants born to mothers taking 6,000 mg or more of vitamin C may develop rebound

scurvy because their intake of vitamin C drops after birth.

Recommended dietary allowance for vitamin C(4)

Problem Statement :

Which type of juice provide the most vitamin C?

Hypothesis :

The higher the volume of fruit juices needed to decolourise DCPIP solution, the lower the

vitamin C content in the fruit juice. Fresh lime juice has the highest content of Vitamin C among

the fresh juices and orange cartoon juice has the highest content of Vitamin C among carton

juices.

Variables :

Types of Variables Ways to control the variables

Manipulated Variable:

Type of fruit juice

Use different type of fruit juices such as fresh lime juice, fresh lemon juice , fresh orange juice, lime cartoon juice, lemon cartoon juice and orange cartoon juice.

Responding Variables:

Volume of fruit juices needed to decolourise 0.5ml of 1.0% DCPIP solution

Repeat and calculate average volume of fruit juices from each group (fresh and carton juice group) needed to decolourise 0.5ml of 1.0% DCPIP solution using a 10ml syringe.

Fixed Variables:

Volume of DCPIP solution

Concentration of DCPIP solution

Use 0.5ml of DCPIP solution, measured using 0.5ml syringe throughout the experiment.

Use 1.0% of DCPIP solution throughout the experiment.

Apparatus Test tubes, 0.5ml syringe,10ml syringe, beaker, mortar and pestle Materials 1000mg vitamin C tablets, 1% dichlorophenolindophenol solution (DCPIP), freshly squeezed lime, lemon and orange juices, 100ml distilled water, lime, lemon and orange carton juice. Procedure : Preparation of standard solution

1. A full vitamin C weighing 1g was crushed into fine powder with mortar and pestle. 2. The powder was then dissolved in 100ml of distilled water to form 1g/100ml

ascorbic acid. 3. Steps 1 and 2 were repeated thrice to get average volume of vitamin C needed to

decolourise DCPIP solution. 4. Steps 1 until 3 were repeated by using ¾ tablet, ½ tablet, ¼ tablet and ⅛ tablet of

vitamin C to produce 0.75g/100ml , 0.5g/100ml , 0.25g/100ml and 0.125g/100ml respectively.

Preparation of standard curve 1. 0.5ml of 1.0% DCPIP solution was measured using 0.5ml syringe and placed into a test

tube. 2. Then, 1ml of 1g/100ml ascorbic acid was measured using a syringe. 3. The ascorbic acid was titrated drop by drop into test tube containing DCPIP solution. 4. Ascorbic acid was added with extra care, drop by drop until the blue color of DCPIP

solution turn colourless. 5. The volume of 1g/100ml of ascorbic acid was measured and recorded. 6. Steps 1 to 5 were repeated using 0.75g/100ml , 0.5g/100ml , 0.25g/100ml and

0.125g/100ml respectively to obtain respective measurement. 7. A standard curve was plotted base on the results.

Testing the concentration of Vitamin C in fruit juices.

1. 0.5ml of 1.0%DCPIP solution was measured and placed into a test tube.

2. Then, 5ml of freshly squeezed orange juice was measured using a syringe.

3. The needle of the syringe was placed into the DCPIP solution.

4. The freshly squeezed orange juice was added drop by drop to the DCPIP solution. The

mixture gently stirred with the needle of the syringe. The juice is continuously added with

extra care until the DCPIP solution is decolourised. The step is repeated thrice.

5. The volume of fruit juice needed to decolourise the DCPIP solution was recorded.

6. If more than 5 cmᵌ of fruit juice needed to decolourise the DCPIP solution, then one

control colour was set up. With another test tube containing DCPIP solution, fruit juice

was added until the colour changes exactly the same. The volume of fruit juices needed

was recorded.

7. Steps 1 until 5 were repeated by replacing freshly squeezed orange juice with freshly

squeezed lemon juice and freshly squeezed lime juice. The data was recorded.

8. Steps 1 until 5 were repeated by replacing freshly squeezed orange juice with orange

carton juice, lemon carton juice and lime carton juice. The data was tabulated.

9. The concentration of each group of juice and each of the juice was calculated by using

following formula :

Volume of Vitamin C solution needed to decolourise DCPIP solution ,V =

k (gradient in the standard curve graph)

Concentration of vitamin C solution, C

V = k / C

10. The readings obtained were tabulated in the table.

RESULTS

DATA COLLECTION

Concentration

of vitamin C

(g/ml )

Volume of vitamin C needed to decolourise 0.5ml of 1.0%

DCPIP (ml)

Average volume of

vitamin C needed

to decolourise

0.5ml of 1.0%

DCPIP (ml) 1st reading 2nd reading 3rd reading

0.125/100 0.70 0.80 0.75 0.75

0.250/100 0.48 0.47 0.48 0.48

0.500/100 0.40 0.45 0.40 0.43

0.750/100 0.30 0.40 0.35 0.35

1.000/100 0.20 0.25 0.30 0.25

Table 1 : Results of standard solution of Vitamin C

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.125 0.25 0.5 0.75 1

Concentration of ascorbic acid against volume of ascorbic acid needed to decolourise 0.5ml 0f 1.0%

DCPIP solution

Volume ofascorbic acidneeded todecolourise0.5ml 0f 1.0%DCPIP solution

Graph 1 : Standard curve of ascorbic acid

Since , formula from above,

From graph,

When concentration of vitamin C solution is 0.750g/100ml, the volume of vitamin C solution

required to decolourise DCPIP solution is 0.35ml.

k = 0.35ml x 0.750g/100ml

k = 0.263 gml -1

Ave

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0.5

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DC

PIP

(m

l)

Concentration of ascorbic acid

(g/ml)

Group

Volume of juice needed to decolourise 0.5ml of 1.0%

DCPIP (ml)

C = 0.263 g

……..V(ml)

Concentration

of Vitamin C

(gml -1 )

1st Reading 2nd Reading 3rd Reading Average

Freshly

squeezed

juice

Orange 2.3 2.2 2.0 2.2 0.263 / 2.2 0.120

Lemon 1.5 2.5 2.3 2.1 0.263 / 2.1 0.125

Lime 1.8 1.2 1.8 1.6 0.263 / 1.6 0.164

Carton juice

Orange 11.5 12.5 12.0 12.0 0.263 / 12.0 0.022

Lemon 25.3 27.0 26.0 26.1 0.263 / 26.1 0.010

Lime 43.6 37.5 44.9 42.0 0.263 / 42.0 0.0063

Table 2 : Results of volume of fruit juices needed to decolourise 0.5ml of 1.0% DCPIP solution

and finding concentration of vitamin C

DISCUSSION

Analysis of data

An experiment was held to investigate the Vitamin C content in fruit juices based on

standard curve obtained.

A vitamin C with 1.0g/100ml, 0.75g/100ml , 0.5g/100ml , 0.25g/100ml and 0.125g/100ml

was prepared by crushing the vitamin C tablets and dissolving them in 100ml of distilled water.

0.5ml of 1% DCPIP solution was placed in test tube and ascorbic acid was titrated drop by drop

until the DCPIP solution turn colourless. The reading was repeated thrice and average reading

is obtained. Same goes with other readings and obtained reading was used to obtain standard

curve. Fresh fruit juices an carton juices was prepared with three different type of fruits : orange,

lime and lemon. The same steps is repeated with these fruit juices and reading obtained was

tabulated. Concentration of each fruit juice is determined by using following formula: k (gradient

in the standard curve graph) divided with volume of Vitamin C solution needed to decolourise

DCPIP solution ,V

The dependant variable is the type of fruit juice. Different type of fruit juices such as

fresh lime juice, fresh lemon juice ,fresh orange juice, lime cartoon juice, lemon cartoon juice

and orange cartoon juice was used to observe clearly the difference between vitamin C content

in different fruit juices. The independent variable in this experiment is the volume of fruit juice

needed to decolourise 0.5ml of 1.0% DCPIP solution The results are precise and valid since the

a standard curve obtained and the gradient was used to determine the concentration of each

and every fruit juices. The lower the volume of fruit juice needed to decolourise the DCPIP

solution, the higher the vitamin C content in that precise fruit juice.

There are some variables that are kept constant throughout the experiment. Such

variable is the volume of DCPIP solution because we need the same amount of DCPIP solution

so that it won’t effect the result of experiment. Besides that, the concentration of DCPIP solution

also kept constant at about 1.0% so that it won’t influence the experimental data.

Table 1 shows the vitamin C concentration and the volume of vitamin C needed to

decolourise blue DCPIP solution. Based on table 1, there were five different vitamin C

concentrations. The concentrations of these standard solutions or ascorbic acid are1.0g/100ml,

0.75g/100ml, 0.5g/100ml , 0.25g/100ml and 0.125g/100ml respectively. Three readings were

taken and average reading was obtained for the amount of ascorbic acid needed to decolourise

DCPIP solution.

The amount of ascorbic acid used to decolourise blue DCPIP solution varies for each

concentration. The higher the concentration, the smaller the amount of ascorbic acid needed to

decolourise the blue DCPIP solution. Using the data in table 1, a graph was sketched and a

best fit line drawn. It can be seen that the best fit line in the graph decreases from 0.125g/100ml

to 1.0g/100ml concentration of vitamin C.

In the other hand, Table 2 shows the concentration of vitamin C of different freshly

squeezed fruit juice and carton fruit juice based on volume needed to decolourise DCPIP

solution. There were three different juices (orange, lemon and lime) used in this experiment

classified in two groups : freshly squeezed fruit juice and carton fruit juice. In the first group(

freshly squeezed fruit juice), the highest volume needed to decolourise DCPIP solution is 2.2ml

(orange juice) while smallest reading obtained is 1.6ml (lime juice). For the second group

(carton juice), the highest volume needed to decolourise DCPIP solution is 42.0ml (lime juice)

while smallest reading obtained is 12ml (orange juice).

Using the standard graph, the gradient of the line was calculated and marked as k.

Using that k value, concentration of both fruit juice group was calculated and recorded. By

calculation, it is determined that in the first group, lime juice has the highest concentration

(0.164 gml -1)and the lowest possessed by orange juice (0.120 gml

-1). While for the second

group, highest concentration is by orange (0.022 gml -1) and the lowest is lime juice

(0.0063 gml -1).

From the standard best fit line graph. It can be seen that as concentration of vitamin C

increases, volume of ascorbic acid needed to decolourise DCPIP solution decreases. Thus, the

higher the vitamin C content, the lower the volume needed to decolourise DCPIP solution.

Evaluation

Limitation and improvement

Several limitation are found in this experiment. Fruits in this experiment were prepared earlier by

the laboratory assistant, thus the fruits had been exposed to air for period of time before the

experiment conducted. The air surrounding oxidized the fruit that already been cut into half

therefore reduce the amount of vitamin C in fruits. Exposing fruits before experiment should be

avoided to get accurate results.

Furthermore, beakers containing both freshly squeezed juice and carton juice were not covered

during experiment also causes the surrounding air to oxidized vitamin C contain in the juice.

Thus, it further reduce the amount of Vitamin C resulting in inaccurate results. Care should be

taken by covering mouth of beaker to prevent further oxidation.

Another limitation is the presence of fruit residue (pulp) in juices. Since we didn’t sieve the fruit

juice, some residue may have taken space in syringe and this reduce the accurancy of this

experiment. The presence of air bubbles in syringe too gives less accurate reading for the

volume of fresh juice needed to decolourise the 5ml of 1.0% DCPIP solution. Repeating the

experiment will enable us to get average reading and volume needed can be calculate more

accurately.

Validity and reability

For ensure the validity of the results, the ascorbic acid reading and volume of fruit juice needed

to decolourise DCPIP solution was taken thrice per every concentration. Obtaining average

reading will minimize random errors, thus ensure the validity and reability of the data.

Extra care was taken when squashing the fruits. The fruits were squeezed without

pounding them hard on table or prevent from squeezing too hard to prevent formation of

frictional force which will produce heat which will destroy part of the vitamin C. This guarantee

the validity and reability of data.

The test tubes containing fruit juices also not shaked to preserve vitamin C in the

juices. Shaking will enable oxidation which will reduce vitamin C concentration resulting in no

valid data. This means the result is more reliable and valid.

Safety precaution

In order to avoid any accident or injury during the experiment in laboratory, the

precautionary steps should be taken and applied. Wearing lab coat and a pair of suitable shoes

are compulsory when conducting an experiment in the lab at all times to protect the skin and

clothing from chemical substance. This is to ensure that no juice is spilled to our skin and

clothing as it will stain badly. Furthermore, the glassware such as beakers and boiling tubes

should be handled with full care because they are fragile. Not only that, sharp objects such as

syringe’s needle must be used properly to prevent any contamination and injuries. When taking

measurements form the apparatus, make sure to avoid any human error such as parallax error.

It is very important to take the reading of absorbance at least three times to get a more

accurate, valid and reliable result. Avoid consuming any juices in experiment because they

might be contaminated.

Conclusion

Every fruit group has different concentration of vitamin C. the smaller the volume of fruit

juice needed to decolourise DCPIP solution, the higher the content of vitamin C in fruit juice.

Fresh juice contain more vitamin C content than carton fruit juices. Fresh lime juice has the

highest vitamin C content and lime has the lowest vitamin C content among fresh fruit juices

while for carton fruit juices, orange has highest and lime has the lowest content of vitamin C. the

hypothesis is accepted.

Reference

1. http://en.wikipedia.org/wiki/Vitamin_C

2. http://www.whfoods.com/genpage.php?tname=nutrient&dbid=109

3. http://www.lenntech.com/fruit-vegetable-vitamin-content.htm

4. http://www.google.com.my/search?q=vitamin+c&hl=en&safe=off&biw=1366&bih=681

&prmd=ivnsr&tbm=isch&tbo=u&source=univ&sa=X&ei=1fpaTvWAKorlrAfj68mSDQ&ved

=0CGIQsAQ