Mold & yeast preservatives for hair shampoo syndet bars

[Garden Gives Me Joy]

I am experimenting with making my own syndet hair shampoo bars and came across advice to use a 'preservative booster or co-preservative' along with PhenoxyEthanol (PhE) because PhE is weak at combatting mold and yeast. I feel particularly motivated to look into this because of my extremely high humidity (rain forest) climate, especially if I use additives like amino acids, herbal additives like aloe powder, colloidal oats and other ingredients likely to require special attention regarding preservation.

I gather that CITRIC ACID is one such booster / co-preservative. Also, my bar has a pH of 6. When I began to research matters like usage rate, testing the preservative, etc, I felt daunted upon reading that "although the majority of yeasts and molds are obligate aerobes (require free oxygen for growth), their acid/alkaline requirement for growth is quite broad, ranging from pH 2 to above pH 9."

Outside of / prior to lab work, how do I test for successful preservation? If I should test several iterations at various pH levels, what range should I consider? Outside of placing bars in environments that would ordinarily cause mold, how do you test for mold or other spoilage?

Also happy for options in addition to citric acid that are relatively easy to find and ideas on how to approach them.

Thanks

 

[lsg]

Optiphen Plus is what I used in my syndet bars. Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid. Humblebee & me. You might consider Phenonip. Syndet poo and preservatives

 

[paradisi]

I am experimenting with making my own syndet hair shampoo bars and came across advice to use a 'preservative booster or co-preservative' along with PhenoxyEthanol (PhE) because PhE is weak at combatting mold and yeast. I feel particularly motivated to look into this because of my extremely high humidity (rain forest) climate, especially if I use additives like amino acids, herbal additives like aloe powder, colloidal oats and other ingredients likely to require special attention regarding preservation.

I gather that CITRIC ACID is one such booster / co-preservative. Also, my bar has a pH of 6. When I began to research matters like usage rate, testing the preservative, etc, I felt daunted upon reading that "although the majority of yeasts and molds are obligate aerobes (require free oxygen for growth), their acid/alkaline requirement for growth is quite broad, ranging from pH 2 to above pH 9."

Outside of / prior to lab work, how do I test for successful preservation? If I should test several iterations at various pH levels, what range should I consider? Outside of placing bars in environments that would ordinarily cause mold, how do you test for mold or other spoilage?

Also happy for options in addition to citric acid that are relatively easy to find and ideas on how to approach them.

Thanks

Citric acid is not a booster or co preservative. It's a pH adjuster.

 

[justjacqui]

As mentioned above citric acid is not a preservative or booster.

I recommend looking at this website for preservative reviews

Preservative Reviews -

Sodium Benzoate and Potassium Sorbate are good against yeast and fungi but do need to have a pH of around 5 or less for the best performance. Ethylhexylglycerin is a booster that might give you a small amount of activity against fungi but not as good as the benzoates and sorbates. It can usually be purchased as a blend with Phenoxyethanol.

Hope this helps