Full experimental rough plan.

1st experiment: Effect of exposure to air on retention of vitamin C in orange juice.
2nd experiment: Effect of temperature on retention of vitamin C in orange juice.
3rd experiment: Effect of material of container on retention of vitamin C in orange juice.
Final concluding experiment: Best way to store orange juice for the retention of the vitamin C content.

For the 1st to the 3rd experiments, they will be individual experiments where all other factors that may affect the pH level of orange juice will be kept constant in all setups. For example, for the 1st experiment, I will make sure that both setups are kept in the same, constant temperature and only test how the exposure to air affects the degradation of vitamin C / ascorbic acid in the orange juice samples.

In the final concluding experiment, I will make use of all the data that I have collated from the first 3 experiments to form a setup that has the best potential (eg. low temp, very little exposure, glass container) to retain as much of the vitamin C content in the orange juice. I will then be able to conclude my entire Science Investigative Experiment after finding out what is the best way to store orange juice to minimise the degradation of the vitamin C content. These findings, combined, will then be useful and helpful information to people who like to drink orange juice, or drink orange juice for its nutritional content (vitamin C).