Using Fresh Herbs in Cosmetic Formulations

Regarding your question about using fresh Centella Asiatica (ใบบัวบก) juice in a cream formulation, the staff's advice is correct. It is generally not recommended to use fresh herbal materials like blended juice directly in cosmetic creams for several important reasons:

• Microbial Contamination: Fresh plant materials naturally contain a high load of bacteria, fungi, and yeast. Introducing these into a cream formulation, even with preservatives, makes it very difficult to control microbial growth, leading to spoilage, instability, and potential safety risks for the user.
• Inconsistent Efficacy: The concentration of active compounds in fresh plants can vary greatly depending on factors like growing conditions, harvest time, and processing method. This makes it hard to achieve consistent results in your final product.
• Stability Issues: Fresh plant extracts can contain enzymes and other compounds that can degrade other ingredients in your cream or cause the formulation to separate or change over time.

Instead of fresh juice, it is highly recommended to use cosmetic-grade herbal extracts, such as Centella Asiatica extract. These extracts are processed under controlled conditions to ensure microbial safety, consistent active compound concentration, and better stability in formulations.

Preservatives for Cosmetic Creams

To extend the shelf life of your cream and protect it from microbial contamination, you need to incorporate a suitable preservative system. Preservatives work by inhibiting the growth of bacteria, mold, and yeast.

There are various types of cosmetic preservatives available, each with different properties, pH ranges, and usage rates. Some common examples include:

• PE 1090 Preservative: A broad-spectrum preservative effective in a wide pH range (3-12). Typical usage rate is 0.5-1.0%.
• Mild Preserved Eco™: Not classified as a traditional preservative by some regulations, it helps prevent spoilage and can also offer moisturizing properties. Typical usage rate is 1.0-1.5% for general formulas.
• NaturePreserve™ Ultra: A natural preservative blend (Gluconolactone & Sodium Benzoate) effective in a pH range of 3-6. Typical usage rate is 0.75-2.0%.
• Thyme Care™: A natural preservative extracted from Thyme and other plants, effective at 0.8% in a pH range of 2-10. Note that it has a natural thyme scent.
• Mild Preserved™ COS: A broad-spectrum, water-soluble preservative effective in a pH range of 2-8. Typical usage rate is 0.75-1.5%.

Usage Rate and Challenge Testing

The correct usage rate for a preservative depends on the specific preservative, the composition of your cream (e.g., water content, presence of natural ingredients), and the desired shelf life. Always follow the manufacturer's recommended usage rate for the specific preservative you choose.

Crucially, after formulating your cream with a preservative, you must perform a challenge test. This is a laboratory test that involves intentionally introducing microorganisms into your product to ensure that the preservative system is effective at preventing their growth over time. This is essential for ensuring the safety and stability of your cosmetic product.

Using cosmetic-grade ingredients and properly tested preservatives is key to creating safe, stable, and effective cosmetic formulations.