Adding Xanthan Gum and Homogenizer Speed in Vitamin C Serum Formulation

Question

I have the following serum formulation. Could you advise on when to add Xanthan gum and what speed to use with a homogenizer?

Formula:

Phase A:
- Distilled Water: 43.7g
- Triethanolamine (TEA): 2.5g (for pH adjustment to approx. 3.7)
- Ferulic Acid: 0.5g (Antioxidant, helps stabilize LAA Vitamin C)
- Panthenol (Pro Vitamin B5): 0.5g (Skin moisturizer)
Phase B:
- Ethoxydiglycol: 20g (Solvent, penetration enhancer)
- Propylene Glycol: 10g (Solvent, lubricant)
- glycerin: 3g (Lubricant, moisturizer, provides slip)
- Laureth-23: 3g (emulsifier)
- d-Alpha Tocopherol (Vitamin E): 1g (Helps stabilize Vitamin C, antioxidant)
Phase C:
- L-ascorbic acid (Vitamin C): 15g

Questions:

When should I add Xanthan gum to this formula?
What speed should I use with a homogenizer?

Answer 1

Based on the formula you provided, which includes a water phase (Phase A) and other ingredients, Xanthan gum, which is a water-soluble thickener, should typically be added to the water phase (Phase A).

To prevent clumping, it's best to first disperse the Xanthan gum in a small amount of liquid from Phase A (like distilled water) or in the glycerin from Phase B before adding this dispersion to the rest of Phase A while stirring continuously. Ensure it is fully hydrated and lump-free before proceeding.

Regarding the homogenizer speed, the optimal speed depends on the specific homogenizer model and the desired viscosity and stability of your final serum. Generally, you would start with a lower speed to incorporate the phases and then gradually increase it as needed to achieve a smooth, stable emulsion or dispersion. Avoid excessively high speeds initially, which can sometimes introduce air bubbles. You may need to experiment to find the best speed for your equipment and formulation.

Answer 2

Update 2026-05-24: The earlier guidance is still broadly correct, but for this 15% L-ascorbic acid / Vitamin E / Ferulic Acid style formula, Xanthan Gum should be wetted, dispersed, and fully hydrated before the system becomes strongly acidic and solvent-rich. A practical process is: pre-wet Xanthan Gum in glycerin, or sprinkle it slowly into the water phase while stirring, mix until lump-free, then add the glycol/solvent phase gradually, and add L-ascorbic acid near the end. For serum texture, start low, about 0.1-0.3% Xanthan Gum as a trial; higher levels can become too thick, sticky, or stringy.

A homogenizer is not required if the gum is dispersed correctly. Use low-to-moderate mixing first, and use high shear only briefly if clumps remain. After L-ascorbic acid is added, avoid prolonged high-speed homogenizing because air incorporation can accelerate Vitamin C oxidation. Measure the final pH after the whole formula is fully mixed; do not rely only on the calculated amount of Triethanolamine. Because the formula contains water, preservative suitability and microbial stability must also be checked. Use air-tight, light-protective packaging and minimize heat, air, and light exposure.

References: Lin et al., Journal of Investigative Dermatology, 2005, on Vitamin C/E/Ferulic systems; García-Ochoa et al., Biotechnology Advances, 2000, on Xanthan Gum properties.