Vitamin C Stability, pH, and Color Change

Hello,

Based on the staff's reply, here are the answers to your questions:

• Effect of pH on Vitamin C effectiveness: Adjusting the pH to 3.5-4 will cause Vitamin C to degrade faster. A pH of 3.5 is recommended as the most suitable level for products intended for sale, as it is acceptable by the FDA and helps prevent Vitamin C from degrading too quickly.
• Color change upon storage: Long-term storage and/or storage in unsuitable conditions (exposure to air, light, or heat) will cause Vitamin C to degrade. This degradation leads to a darkening of the product's color, changing from light yellow to dark brown, regardless of the specific formula (like Vitamin C E Ferulic Acid).