A quick guide to Cosmetic Preservatives
What is a Preservative?
Preservative is an ingredient which protects the products from going bad or contaminated. It increases the shelf life of the product.
Why are preservatives needed?
Preservatives are absolutely necessary to prevent from bacterial growth and mold. Whenever there is a chance of introduction of water, it can lead to bacterial growth.
We cannot see microbial growth with the naked eye. Yeast and mold may appear like black or white spots, or yellowish layer. Other ones, cannot be detected directly.
Unpreserved products can lead to skin diseases and skin infections. Fresh products are house for microbial growth. Even fruits, milk go bad and decay. Using high amount of oil, glycerine, salts or sugar like 70-80% can reduce microbial growth but using at a higher rate is not practical for many applications.
Broad Spectrum Preservatives:
Few preservatives work against gram positive bacteria, few against gram negative bacteria or yeasts or mold or fungi. So, often preservatives are combined to form a broad spectrum preservative. Broad spectrum preservative means which protects the product from gram positive/negative bacteria, yeasts, mold and fungi. It covers protection against all kinds of microbial growth.
Difference between Gram Positive and Gram Negative Bacteria:
Gram stain is a laboratory test that detects bacteria and sometimes fungi.
Gram staining is what makes bacteria to be gram positive or negative and this happens because gram positive bacteria have thick peptidoglycan which retains crystal violet staining dye as opposed to gram negative. Gram negative bacteria stains red or pink.
Gram positive bacteria have cell walls composed mostly of a substance unique to bacteria known as peptidoglycan, or murein.
Tips to improve preservation:
- Try to reduce the amount of water content.
- Add chelating agent like EDTA, sodium gluconate or others.
- Add preservative booster like Propanediol 1,3
- Use containers that are less possible to contaminate with water products. Example: plastic or glass and not metals.
- Do not add high amounts of electrolytes like aloevera, sodium lactate etc.
- Check and adjust pH to cover preservative range.
- Combine two preservatives to cover a broader range.
- Avoid dipping fingers in products.
- Follow GMP (Good Manufacturing Practises). May be will have another blog on this topic :D
Are you confused on which preservative to be used for a product? We have this sorted for you. Check out the preservatives that we have and how to use.
Phenoxyethanol
It is active against gram negative bacteria but weak against mold and yeast. Preservative booster is needed.
Not a broad spectrum preservative.
- Usage rate: 0.25-1%
- Type: Liquid
- pH: 7.0 (at 1%)
- Stable up to 85’C
- pH compatibility range: 3-10
- Soluble in: oils, miscible in propylene glycol and glycerine, not completely soluble in water.
- Can be combined with Potassium Sorbate between 0.1-0.2% to cover for yeast and mold.
- Applications: Shampoo, shower gels, washoff products, creams and lotions.
- Preservative gets inactivated by highly ethoxylated compounds like PEG’s.
Preservative Eco
It is a natural broad spectrum preservative. Can be used alone. Also known as Geogard ECT or Microkill ECT. Protection against gram positive, gram negative, yeasts and molds.
- INCI: Benzyl alcohol & Salicylic Acid & Glycerin & Sorbic Acid
- pH compatibility range: 3-8% (effective under 5.5)
- Usage rate: 0.6-1%
- Applications: Creams, lotions, lipsticks, shampoos, haircare, makeup, scrubs
- Type: Liquid
- Solubility: Not completely soluble in water.
- Not recommended for children products under the age of 3 specifically for products due to presence of Salicylic acid.
- Temperature: Below 40’C, can be added in cool down phase.
- Extends shelf life of personal care products typically to 6-18 months
Potassium Sorbate
Natural preservative but is not a broad spectrum. It is effective against molds, yeasts and aerophile bacteria.
- Solubility: Water
- pH range: 2-6.5, most active at pH 4.4
- Usage rate: 0.1- 0.2% in combination with other preservatives
- Type: prills, mix in water
- Applications: creams, lotions, hair care, sunscreen, makeup products.
- Can be combined with sodium benzoate, gluconolactone or phenoxyethanol
- Temperature: Under 60’C
Sodium Benzoate
- Natural preservative, often used with potassium sorbate to preserve low pH products against yeast and mold. Not broad spectrum.
- Soluble in water
- Usage rate: up to 1%
- Type: powder
- pH range: 4.5 or less
- Applications: skin care, hair care, makeup and oral care
Benzyl alcohol
- Natural preservative, not a broad spectrum. Often used with potassium sorbate and phenoxyethanol. It is the constituent of essential oils. It acts as a solvent.
- Usage rate: 0.5-1%
- pH range: less than 5.5
- Applications: skincare, haircare, makeup and nail products
- Soluble in: ethanol, not completely water soluble
Methyl Paraben
- Parabens are one of the strongest and effective preservatives which have been used from years. Often when clays or natural powders are used, it increases the chances of contamination. To preserve these kind of products, parabens are used. Can be combined with propyl paraben.
- Parabens got a bad reputation due to a study that found parabens in cancer
tissues of a woman. But the study didn’t say that parabens are from skin care products or the parabens caused cancer. This got spread widely and usage of parabens reduced. - Parabens are found even in natural fruits like blueberries.
- Type: Powder
- Methyl Paraben Sodium is Soluble in Water and Methyl Paraben Plain is insoluble in water
- Applications: Soaps, detergents, personal care
- Usage rate: 0.1-0.4%
Propyl Paraben
- Type: Powder
- Propyl Paraben Sodium is Soluble in Water and Propyl Paraben Plain is insoluble in water
- Applications: creams, lotions, hair care, cosmetics, bath products, lip gloss, eye liner, mascara
- Usage rate: 0.05-0.1%
- Shouldn’t be used for kids products under age of 3
CMIT/MIT 14% Isothiazolinone
- Broad spectrum preservative, not suitable for children under age of 3 or for sensitive allergy prone skin.
- Applications: hair care, cosmetics, skin care
- Usage rate: 0.05-0.3%
DMDM Hydantoin
Broad spectrum preservative. Products can be preserved effectively with less amount of preservative.
- Type: Liquid
- Applications: Shampoos, hand soaps, face creams, sunscreens, lotions.
- Usage rate: 0.1-0.6%
- pH: 4-10
- Soluble in: water
- Extends shelf life of personal care products typically to 6-18 months
Reference links:
https://www.fda.gov/cosmetics/cosmetic-ingredients/parabens-cosmetics
Comments
Thanks a lot