Proposal.

APPENDIX D
Science Investigative Project
Project Proposal Form
Name: Nicole Pua Kai Qian ( 24 )
Secondary: 2/10

Topic of investigation: Retention of Ascorbic Acid (Vitamin C) in Orange Juice

Observations made
I noticed that freshly squeezed orange juice left in the fridge tastes slightly more sour than the juice placed outside in room temperature for the same amount of time.
I also realised that when I left freshly squeezed orange juice uncovered and exposed in the open, it turns darker shades of orange faster as compared to the juice kept in a capped bottle or in the fridge. The orange juice that was left exposed also lost a great deal of its flavour and taste. The juice in the bottle took a longer time to change colour, and only started to turn brown after six months, losing much of its original flavour. Whereas, the juice in the fridge kept its fresh look and flavour for a much longer time.

Research Question
Does temperature affect the retention of vitamin C (ascorbic acid) in orange juice?
Does exposure [to air] affect the retention of vitamin C (ascorbic acid) in orange juice?
What is the best way to store orange juice so as to minimize the degradation of vitamin C?

Hypothesis statement
The lower the temperature, the better the retention of vitamin C.
The less exposed the orange juice is, the better the retention of vitamin C.
It is best to store orange juice without exposure to the surrounding air and in cold temperatures to minimize the degradation of vitamin C.

A short summary of research done on the area of investigation
Vitamin C, ascorbic acid, is one of the most important vitamins found in citrus juices, including orange juice. This ascorbic acid can be measured by seeing the pH level of the juice, determining how much vitamin C the juice possesses. The lower the pH level, the higher the amount of ascorbic acid/vitamin C. There are many factors that affect the vitamin C contents of citrus fruits such as oranges. Five main affecting factors are climate conditions (especially temperature), maturity state and position on tree, type of citrus fruit, type of container, and handling and storage.
As for temperature, research has shown that total available heat affects vitamin C levels. Areas with cool nights produce citrus fruits with higher vitamin C levels while hot tropical areas produce fruit with lower levels of vitamin C. Environmental conditions that increase the acidity of citrus fruits also increase vitamin C levels. Other experiments have also shown that there is a better retention of ascorbic acid in orange juice in colder temperatures. 

Oxygen in the air is the most destructive ingredient in juice causing degradation of vitamin C. One of the major sugars found in orange juice, fructose, can also cause vitamin C breakdown. The higher the fructose content, the greater the loss of vitamin C. Conversely, higher acid levels of citric and malic acids stabilize vitamin C. Orange juice must be stored at proper cool temperatures with oxygen barriers for best retention of vitamin C levels. 

Orange juice changes in colour due to oxidation, with nothing whatsoever to do with bacteria cultures. The juice is perfectly safe to drink due to the pasteurization process, but after it changes colour, it loses much of its flavour. This is due to the depletion of vitamin C/ascorbic acid in the juice, also causing a decrease in nutritional value.

Bibliography
Townsend, C. (2006, February 1). Vitamin c and citrus juices. Retrieved from http://www.ultimatecitrus.com/vitaminc.html
Chu, M. (2004, October 2). Orange juice shelf life. Retrieved from http://www.cookingforengineers.com/article/7/Orange-Juice-Shelf-Life
Abbasi, A., & Niakousari, M. (2008). Kinetics of ascorbic acid degradation in un-pasteurized Iranian lemon juice during regular storage conditions. Pakistan Journal of Biological Sciences, 11 (1028-8880). Retrieved from https://docs.google.com/viewer?a=v&q=cache:EebKuFZGuDwJ:scialert.net/pdfs/pjbs/2008/1365-1369.pdf+%22effect+of+storage+temperature%22%2BpH%2Bjuice&hl=de&gl=de&pid=bl&srcid=ADGEESgQcpIKg_bokFdpuGgv27P1beUpZ77hLsc1QQvIBaydoeJQPP7sxfQVI3AN0liSQGWNIKt5u34OhQAbLJiTGary__ybpZ9ekr45r2k7HVotBqE1l_vDXS3b0-FRJZQhpkWPrLhv&sig=AHIEtbRLEfJPZ2V9nDZNwEi_nh2EVwlaWw&pli=1
Kohler, J. (1998). The best way to store freshly made juice. Retrieved from http://www.discountjuicers.com/storingjuices.html