What happens to the concentration of vitamin c in apple juice over time?
The expert in the Link below says that the amount of vitamin C in fruits can only decrease with time after the fruit is harvested, it cannot increase. However, if your carton was left open, it is possible that the fruit juice lost water by evaporation faster than the vitamin C got oxidized. (Evaporation happens even if the carton is stored in the fridge.) So although the TOTAL AMOUNT of vitamin C in the carton would have decreased over the 19 days, the CONCENTRATION of vitamin C could have increased, because it is now dissolved in less water.
