How does temperature affect vitamin c?

Vitamin C is highly sensitive to air, water, and temperature. Crystalline substances, including vitamin C, some vitamin B forms and other dietary supplements, are prone to a process called deliquescence, where humidity causes a water-soluble solid to dissolve and leach out of the vitamins. Exposure to elevated temperatures accelerates the degradation of vitamin C and destroys its ability to act as an anti-oxidant or otherwise provide any benefit. While vitamin C can degrade even without the oxygen in air, exposure to air is usually part of the process of degrading it. Even if it it packaged in nitrogen, as soon as a package is opened, it is exposed to the oxygen in the air and begins to degrade. Exposure to light can also hasten the degradation of vitamin C. Maximum storage time requires keeping vitamin C cool, dry, away from oxygen and away from light.