Preserving Boiled Kaffir Lime Mixture with Paraben-Free Preservatives

Okay, boiling the kaffir lime mixture is a good step to reduce the initial microbial load. However, to ensure the product remains stable and safe for use over time, especially with a high water content (97%), adding a broad-spectrum preservative is essential. This will prevent the growth of bacteria, yeast, and mold that can be introduced during mixing or use.

Since you want a paraben-free preservative, here are a few suitable options:

• NaturePreserve™ Ultra (Gluconolactone & Sodium Benzoate): This is a 100% natural preservative effective against bacteria, fungi, and yeast. It's water-soluble and works in a pH range of 3-6. The recommended usage rate is 0.75-2.0%, typically 1.25% for general products. It's heat tolerant and mixed into the water phase. Note that it might slightly lower the pH.
• Global Guard™ 221 (Dehydroacetic Acid & Benzyl Alcohol & Water): This is a water-soluble, broad-spectrum preservative that is globally approved. It works in a pH range of 2-7. The usage rate is 0.5-1.1%. It should be added when the mixture temperature is below 45°C.
• Mild Preserved™ COS (Phenoxyethanol & Chlorphenesin & Caprylyl Glycol): A broad-spectrum, water-soluble preservative with no odor. It works in a wide pH range of 2-8. The usage rate is 0.75-1.5%. Add it when the mixture temperature is below 45°C.
• Zinc-Ben (Sodium Benzoate & Zinc Acetate): This is a water-soluble, broad-spectrum preservative effective in a pH range of 3-8. It's odorless and can be used in cosmetics. The usage rate is 0.625%. Add it when the mixture temperature is below 45°C.

All these options are paraben-free and suitable for your formulation. Choose one based on your preference for natural ingredients, desired pH range, and ease of use.

Mixing Instructions:

1. Prepare your kaffir lime juice/pulp mixture by boiling and then letting it cool down.
2. Once the kaffir lime mixture has cooled (ideally below 45°C, especially for Global Guard™ 221, Mild Preserved™ COS, and Zinc-Ben; NaturePreserve™ Ultra is more heat tolerant but cooling is still recommended before adding other ingredients), add your chosen preservative at the recommended usage rate. Stir well to ensure it is fully dissolved and evenly distributed.
3. Add the olive oil (3%) to the preserved kaffir lime mixture. Stir or mix thoroughly to combine. Since this is a simple mixture without an emulsifier, the oil and water phases may separate over time, which is normal. You will need to shake before each use.
4. Check the pH of the final mixture to ensure it is within the effective range of the preservative you chose. Adjust if necessary.

Remember that for any product intended for sale, a challenge test is crucial to confirm the preservative system is effective for your specific formula.