By: Siobhan Dougherty

PROBLEM

Which kind of orange juice,

frozen, bottled, or freshly

squeezed, contains the most

amount of vitamin C?

BACKGROUND INFORMATION

Orange juice is a good source of vitamin C and potassium

Vitamin C is necessary for normal growth and development

The process of concentrating OJ results in a slight loss of vitamin C

Frozen orange juice is about 3x more concentrated than regular

orange juice

The original amount of oxygen and carbon dioxide in a can of

orange juice changes over time.

Some bottled juice may be fresher than others, and therefore may

contain different amounts of vitamin C.

Redox titration is a common method of determining the amount of

vitamin C in a substance, represented by the formula: I2 + starch

(C6H10O5) = starch-iodine complex.

HYPOTHESIS

If the amount of vitamin C in

different samples of orange juice

(bottled, frozen, and freshly

squeezed) was measured by using

a starch-iodine indicator, then the

frozen orange juice would contain

the most amount of vitamin C.

MATERIALS freshly squeezed orange juice bottled orange juice frozen orange juice three 50.0 mL beakers one 300. mL beaker one 1.00 L beaker medicine dropper stirring rod one 500. mg vitamin C tablet mortar and pestle goggles

apron gloves 2.00 grams of corn starch distilled water bunsen burner wired gauze tripod 1.00 mL of tincture of

iodine lighter paper pencil

PROCEDURE Make the starch-iodine solution by filling a 300. mL beaker with 200.

mL of cold distilled water Add 2.00 grams of corn starch to the 200. mL of distilled water Bring mixture to a full boil using a bunsen burner (making the starch

solution) Fill a liter beaker with water Add 8.00 mL of the starch solution and 1 mL of tincture of iodine to

the 1 liter beaker of water, which completes the making of the vitamin C indicator (will become a dark blue color)

Stir gently Pour 15.0 mL of this indicator into a 50.0 mL beaker Use a medicine dropper to obtain a sample of the freshly squeezed

orange juice Add this sample drop by drop to the beaker of the vitamin C indicator Gently swirl Continue to add the freshly squeezed orange juice, drop by drop, to

the vitamin C indicator until the indicator turns from blue to colorless *make sure to swirl gently after each drop*

CONTINUED… Record the amount of drops it took to for the freshly squeezed

orange juice to turn the vitamin C indicator colorless Repeat steps 6-12 for four more trials with the freshly

squeezed orange juice Repeat steps 6-13 with the frozen orange juice and then the

bottled orange juice Record Results (number of drops) Repeat steps 6-12 for the distilled water (note: only one trial is

done with this control) Obtain a mortar and pestle Completely crush a 500. mg vitamin C tablet using the mortar

and pestle Mix this crushed tablet with 100. mL of distilled water Fill a 50.0 mL beaker with 15.0 mL of the vitamin C indicator Add the tablet and water mixture to the indicator drop by drop

until the indicator turns from blue to colorless Record Results (number of drops)

VARIABLES independent variable: type of orange juice (freshly

squeezed, frozen, and bottled)

dependent variable: amount of vitamin C in each sample

of orange juice, expressed by the amount of drops it takes

to titrate the vitamin C indicator (shown by a color change)

controls

positive: vitamin C tablet

negative: distilled water

constants: procedural technique, amount of orange juice

tested for each trial, same vitamin C indicator, place where

the project was conducted

DATA/RESULTS(IN NUMBER OF DROPS)

Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 AVG Stddev CI

bottled orange juice 50.0 48.0 54.0 55.0 53.0 52.0 2.92 2.56

frozen orange juice 12.0 10.0 12.0 11.0 12.0 11.4 0.894 0.784

freshly squeezed orange juice 14.0 15.0 13.0 15.0 13.0 14.0 1.00 0.877

Trial 1 Trial 2 Trial 3 Trial 4 Trial 5

500mg tablet with 100ml water 4 4 4 0 0

distilled water 100 drops and nothing happened

Controls

TTEST RESULTS

fresh sq bottled14 5015 4813 5415 5513 533.2E-09

bottled frozen50 1248 1054 1255 1153 121.8E-09

frozen fresh sq12 1410 1512 1311 1512 13

0.0025

All results are under .05, meaning there is a significant difference between all three

of the samples of orange juice

GRAPHS

CONTINUED…

CONCLUSION

The purpose of this experiment was to test whether there were

varying amounts of vitamin C in different kinds of orange juice.

The experiment concluded that frozen orange juice contained

the most vitamin C (1.67 mg/mL), with freshly squeezed

orange juice close behind, but with bottled orange juice

trailing by a significant amount. These results supported the

hypothesis of the experiment.

Frozen and freshly squeezed orange juices are more beneficial

to humans than bottled orange juice is because those juices

actually satisfy the daily requirement of vitamin C per day,

which is 60 mg.

IF THIS EXPERIMENT WAS TO BE DONE AGAIN…

Changes to be Made

Using more kinds of orange juice other than just frozen,

bottled, and freshly squeezed and more brands of each.

Conducting more trials to ensure accuracy and having all

testing done on the same day in the same environment.

Use a more accurate method, other than a dropper, to

obtain the correct amount of orange juice for each trial.

Sources of Error

The different orange juice samples were stored and

handled before being used for this experiment and the

age and conditions of the products before coming into

possession for the experiment are not known.

WORKS CITED Boyd, J., & Peterson, G. (2010). Quality of Canned Orange Juice. Industrial and Engineering Chemistry,

37(4), 370-373. 

Dolson, L. (2010). What You Need to Know about Complex Carbohydrates. Retrieved October 6, 2010, from About.com website: http://lowcarbdiets.about.com/ od/ nutrition/ a/ starch.htm 

Helmenstine, A. M. (2010). Vitamin C Determination by Iodine Titration. Retrieved October 7, 2010, from About.com website: http://chemistry.about.com/ od/ demonstrationsexperiments/ ss/ vitctitration.htm

Medline Plus. (2009). Vitamin C. Retrieved October 6, 2010, from U.S. Department of Health and Human Services website: http://www.nlm.nih.gov/ medlineplus/ ency/ article/ 002404.htm

Obikoya, D. G. (2010). Iodine Information. Retrieved October 21, 2010, from Seacra Enterprises, Inc website: http://www.vitamins-nutrition.org/ vitamins/ iodine.html

Practically Edible. (2010). Frozen Orange Juice Concentrate. Retrieved October 21, 2010, from http://www.practicallyedible.com/ edible.nsf/ pages/ frozenorangejuiceconcentrate

Rushin, W. (2008). Chemical Analysis by Redox Titration. Retrieved October 19, 2010, from Cary Academy website: http://chem.lapeer.org/ Chem2Docs/ RedoxTitration.html

Shilton, N., & Nally, P. (2001, October 6). The Last Word. New Scientist, (2311). Retrieved from http://www.newscientist.com/ article/ mg17223116.600-the-last-word.html

University of Canterbury. (2007). Determination of Vitamin C by Redox Titration with Iodine. Retrieved October 20, 2010, from http://www.outreach.canterbury.ac.nz/ chemistry/ vitamin_C_iodine.shtml

Clark, N. (1999, June 26). Vitamin C, Supplements and Simple Foods. Rowing News, 6(10), 6. Retrieved from http://books.google.com/ books?id=SU0EAAAAMBAJ&pg=PT5&dq=vitamin+c+in+orange+juice&hl=en&ei=-WeuTMGlPML98Aa4s6zTBA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CEEQ6AEwAg#v=onepage&q=vitamin%20c%20in%20orange%20juice&f=false

Ronzio, R. A. (2003). Orange Juice. In Nutrition and Good Health (2nd ed., p. 478). Retrieved from http://books.google.com/ books?id=1bzCYeHoJ8sC&pg=PA478&dq=orange+juice+vitamin+c&hl=en&ei=UlSuTJhAoL78Aa2mMmaCw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CEUQ6AEwAg#v=onepage&q=orange%20juice%20vitamin%20c&f=false