Cream Developing Sour Smell After 2 Weeks

The sour smell you are experiencing in your cream after two weeks is a strong indicator of microbial contamination, likely bacterial or fungal growth in the water phase of your formulation.

While Fractionated Coconut Oil is stable and not prone to rancidity, the high percentage of water (74%) in your formula provides a favorable environment for microorganisms to grow if not adequately protected.

You used Mild Preserved Eco™ at a concentration of 1%. According to the product information, the recommended usage rate for general cosmetic formulas is 1.0-1.5%. For formulas that are more challenging to preserve, such as those with high water content or natural ingredients, a concentration of up to 2% may be necessary.

Using Mild Preserved Eco™ at the lower end of the recommended range (1%) might not be sufficient to protect a formula with such a high water phase (74%) over time, especially under typical storage conditions or if there was any minor contamination during the preparation process.

Recommendations:

1. Increase Preservative Concentration: In your next batch, consider increasing the concentration of Mild Preserved Eco™ to 1.5% or even 2% to provide more robust preservation for the high water content.
2. Ensure Hygiene: Always ensure all equipment and containers are thoroughly cleaned and sanitized before mixing your ingredients to minimize introducing microorganisms.
3. Proper Storage: Store the finished cream in a cool, dark place and ensure containers are sealed tightly.

Adjusting the preservative level is the most direct way to address the microbial growth issue indicated by the sour smell.