Chemistry Vitamin C
tamin C, ascorbic acid, is one of the most important vitamins found in citrus juices, including orange juice.
Often projects find that orange juices made from frozen concentrated orange juice (FCOJ) have the highest vitamin C levels as compared to freshly squeezed or not-from-concentrate (NFC) juices. This is probably due to the fact that vitamin C degrades over time in fresh and NFC, but doesn't degrade as much in FCOJ due to it being frozen until reconstitution. If one is comparing a NFC product that has been stored for about 3 weeks versus a newly reconstituted FCOJ, the FCOJ would almost certainly have a higher vitamin C concentration. Also another thing to consider is if the FCOJ is reconstituted to the same strength as fresh or NFC. If one doesn't add enough water, then the vitamin C (and other compounds) would be more concentrated. Another consideration is that the vitamin C content changes through the harvest season and orange variety also plays a part. Since most FCOJ is blended to a larger extent than some NFCs, it is entirely possible that the NFC is produced from a variety/season that has a lower vitamin C content.
According to Nagy and Smoot, temperature and storage time affects the percent of vitamin C content of orange fruits and orange juice. Different varieties of oranges also have different levels of vitamin C. The mid-season variety, Pineapple Orange had the highest levels, followed by the main early-season variety, Hamlin Orange. The late-season Valencia Orange had the lowest vitamin C content. Additionally, it was found that the longer the Valencia Orange fruit stayed on the tree, the lower the vitamin C level. (Additional details on these orange varieties can be found from links in The Story of Florida Orange Juice - From the Grove to Your Glass.) Nagy and Smoot also found that in orange juice containers, vitamin C loss was due to oxidation by a residual air layer trapped within the container during processing. The loss was faster in the
Often projects find that orange juices made from frozen concentrated orange juice (FCOJ) have the highest vitamin C levels as compared to freshly squeezed or not-from-concentrate (NFC) juices. This is probably due to the fact that vitamin C degrades over time in fresh and NFC, but doesn't degrade as much in FCOJ due to it being frozen until reconstitution. If one is comparing a NFC product that has been stored for about 3 weeks versus a newly reconstituted FCOJ, the FCOJ would almost certainly have a higher vitamin C concentration. Also another thing to consider is if the FCOJ is reconstituted to the same strength as fresh or NFC. If one doesn't add enough water, then the vitamin C (and other compounds) would be more concentrated. Another consideration is that the vitamin C content changes through the harvest season and orange variety also plays a part. Since most FCOJ is blended to a larger extent than some NFCs, it is entirely possible that the NFC is produced from a variety/season that has a lower vitamin C content.
According to Nagy and Smoot, temperature and storage time affects the percent of vitamin C content of orange fruits and orange juice. Different varieties of oranges also have different levels of vitamin C. The mid-season variety, Pineapple Orange had the highest levels, followed by the main early-season variety, Hamlin Orange. The late-season Valencia Orange had the lowest vitamin C content. Additionally, it was found that the longer the Valencia Orange fruit stayed on the tree, the lower the vitamin C level. (Additional details on these orange varieties can be found from links in The Story of Florida Orange Juice - From the Grove to Your Glass.) Nagy and Smoot also found that in orange juice containers, vitamin C loss was due to oxidation by a residual air layer trapped within the container during processing. The loss was faster in the