Preservatives in Cosmetic Formulations

Here are the answers to your questions regarding preservatives:

1. Shelf life without preservatives, stored in the refrigerator

Formulations without preservatives, even when stored in the refrigerator, will have a significantly shorter shelf life compared to preserved products. Refrigeration slows down microbial growth but does not completely prevent it. The exact duration depends on the ingredients, water content, and hygiene during preparation, but typically it would only last from a few days up to a couple of weeks before microbial contamination could occur. For safety and stability, especially for products intended for repeated use, using a suitable preservative system is highly recommended.

2. Active ingredients that can also act as natural preservatives

Some ingredients offer both skin benefits and natural preservative properties. Based on the available information, examples include:

• PaeoniaPreserve™: A natural preservative derived from Paeonia root extract, which also provides antioxidant benefits to the skin.
• Probio-Protect™: A probiotic ferment that acts as a preservative and also helps moisturize the skin by reducing water loss.

While not strictly "active ingredients" for targeted concerns, ingredients like Mild Preserved Eco™ (containing Ethylhexylglycerin and Propanediol) also offer humectant properties and are not classified as traditional preservatives by regulatory bodies, allowing for "preservative-free" claims.

3. Very gentle preservatives for sensitive skin

For sensitive skin, choosing a mild and non-irritating preservative is key. Based on the descriptions, the following are good options:

• Mild Preserved Eco™: Explicitly described as gentle and non-irritating, suitable for sensitive skin. It also has humectant properties.
• Probio-Protect™: A probiotic-derived ingredient known for its skin-moisturizing benefits, which can be beneficial for sensitive skin. It acts as a preservative without being classified as one.

Other natural options like Thyme Care™ or Coco-Preserve™ exist, but their descriptions don't specifically highlight gentleness for sensitive skin, and Thyme Care™ has a strong scent which might be an issue for some. Mild Preserved™ COS is odorless and broad-spectrum but not specifically marketed as extra gentle for sensitive skin.

It is always recommended to perform a challenge test on your final formulation to ensure the chosen preservative system is effective.