Formula Stability and Kojic Acid Dipalmitate Color Change

Your formula appears generally compatible, and using Kojic Acid Dipalmitate instead of Kojic Acid is a good approach to improve stability and prevent color change.

• Kojic Acid Dipalmitate vs. Kojic Acid: Kojic Acid Dipalmitate is known to be significantly more stable than regular Kojic Acid, which is prone to oxidation and discoloration, especially in aqueous solutions. The description for Kojic Acid Dipalmitate confirms its high stability compared to regular Kojic Acid and indicates a shelf life of at least 2 years. This directly addresses your previous issue with Kojic Acid changing color quickly.
• Role of ActiveProtec™ OX: The inclusion of ActiveProtec™ OX, an antioxidant, further enhances the stability of the formula, providing additional protection against oxidation that could lead to discoloration of sensitive ingredients like Kojic Acid Dipalmitate, although KAD is already quite stable.
• Other Ingredients: Ingredients like Niacinamide (B3), Propylene Glycol, Witch Hazel, Mineral Oil, and Phenoxyethanol are commonly used in cosmetic formulations and are generally stable and compatible with Kojic Acid Dipalmitate within typical usage concentrations and pH ranges (Kojic Acid Dipalmitate is stable in pH 3-9).
• Manufacturing Considerations: Kojic Acid Dipalmitate is oil-soluble and requires heating (around 60-80°C) to dissolve completely in the oil phase (Mineral Oil in your formula) before emulsifying with the water phase. Proper dissolution is crucial for the ingredient's effectiveness and stability in the final product. The thickeners/emulsifiers like NovermerEC2 and Sepgel350 will help create a stable emulsion structure.
• Overall Stability: With the use of the more stable Kojic Acid Dipalmitate and the inclusion of an antioxidant, this formula has a much better chance of remaining stable and maintaining its color over a 1-2 year period compared to a formula using regular Kojic Acid. However, long-term stability for commercial products should always be confirmed through rigorous stability testing under various conditions (temperature, light, etc.).

In summary, the substitution of Kojic Acid with Kojic Acid Dipalmitate, combined with the presence of ActiveProtec™ OX, makes this formula significantly more stable and less likely to experience the rapid color change you observed previously.