Formulation Advice for Your Gel Serum

Thank you for sharing your proposed formula and mixing method. Let's break down the components and address your questions.

Your formula includes several beneficial ingredients:

• Complex gel: Contains Propylene Glycol, Dimethylsilanol Hyaluronate, Hydrolyzed Wheat Protein, and BHT.
• Wild Yam Root Extract: Dissolved in Butylene Glycol and Water.
• L-ascorbic acid: As a separate powder.
• Aloe Vera Gel (Lite): Used as the base.

Your proposed mixing method involves combining the Wild Yam extract solution with Butylene Glycol, adding this to the Aloe Gel base, and finally incorporating the L-ascorbic acid powder.

Stability of L-Ascorbic Acid

L-ascorbic acid (Vitamin C) in its pure powder form is highly unstable when dissolved in water, especially in formulations with a pH above 3.5. It oxidizes rapidly, losing its effectiveness and potentially changing color. Since your base (Aloe Vera Gel Lite) and the Wild Yam extract solution contain water, adding L-ascorbic acid powder to this mixture, even at the end, will likely lead to quick degradation of the Vitamin C.

For a stable Vitamin C product, it is generally recommended to:

• Formulate at a very low pH (around 2.5-3.5) if using L-ascorbic acid, which can be irritating to the skin.
• Use a stable derivative of Vitamin C, such as Ascorbyl Glucoside or Sodium Ascorbyl Phosphate, which are more stable in water-based formulations and at higher pH levels.
• Formulate in a non-aqueous base (like silicone or oil), although this would change the texture significantly from a gel.

Given your proposed method uses a water-based gel, the L-ascorbic acid is unlikely to remain potent for long.

Need for Preservative

You asked if a preservative is needed if the product is stored in the refrigerator and used within 30-60 days. While refrigeration slows down microbial growth, it does not completely prevent it. A water-based formulation like this is susceptible to contamination from airborne microorganisms or contact during use. For a shelf life of 30-60 days, especially with repeated opening and use, it is highly recommended to include a broad-spectrum preservative to ensure the safety and integrity of the product and prevent bacterial or fungal growth.

Conclusion

The proposed formulation method is feasible in terms of mixing the ingredients together, but the stability of the L-ascorbic acid will be a major challenge due to the water content in the base and other ingredients. You will likely see the product turn yellow or brown relatively quickly, indicating oxidation of the Vitamin C.

Additionally, even with refrigeration, a preservative is necessary for a product intended for use over 30-60 days to prevent microbial contamination.

If your primary goal is to deliver stable Vitamin C, you might consider adjusting the formulation to use a stable Vitamin C derivative or a different base system, and always include a suitable preservative.