Influence of simultaneous variations in temperature and relative humidity on chemical stability of two vitamin C forms and implications for shelf life models.

Vitamin C powder ingredients are popular food fortificants and are among the most commonly added nutrients. While information on degradation kinetics and shelf life of vitamin C exists, current models are limited in their applicability to systems where relative humidity (RH) and temperature are varied simultaneously, and where phase transformations occur. This study monitored stability of two forms of vitamin C (sodium ascorbate and ascorbic acid) under various RH and temperature conditions. Vitamin C was measured colorimetrically, and stability data were used to improve understanding of vitamin C shelf life when deliquescence occurs during storage. RH and temperature both significantly impacted vitamin stability, though RH had a larger effect. Vitamin dissolution preceded extensive degradation and was found to be a good predictor of vitamin C loss. This research highlights the importance of considering phase transformations when constructing shelf life models and maintaining vitamin C in the solid state for enhanced stability.