Investigation of the effect of different formulation factors on the shelf life of Vitamin C in aqueous solutions

Vitamin C (Vit C)is sensitive to oxidation therefore, the preparations containing Vit C should assure its stability. The aim of this research was to stabilize Vit C in aqueous solutions containing viscosity-increasing agent (HPMC or chitosan) by modifying HPMC concentration or by solvents addition of different polarities and viscosities (eg. glycerin or alcohol). Solutions were characterized for appearance, pH, spreadability and stability. Kinetic of Vit C degradation was estimated by determining reaction orders, rate constants and shelf lives (t₉₀). The results showed that t₉₀ enhanced when glycerin and alcohol were added in solutions. Viscosity and low water activity enhanced Vit C stability (when glycerin increased). Chitosan had a positive effect on stability as it prolonged the shelf life of Vit C to almost 40 days.