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Unusual Preservative Testing Results
I recently sent some samples of body wash to Schulke for preservative testing including two unpreserved samples and when I got the results back all of the samples (including the unpreserved samples) showed no growth during the test.I have seen this before with an unpreserved hair conditioner sample but assumed that the low pH (~4) and all of the cationics including cetrimonium chloride were responsible for that result. The unpreserved shampoo I sent at the same time as the conditioner failed the test.Would any of the following ingredients cause the product to essentially be self preserving.- Ammonium Lauryl Sulfate
- Disodium Cocoamphodiproprionate,
- Cocamidopropyl betaine
- Plantapon SF (Sodium Cocoamphoacetate, Glycerin, Lauryl Glucoside, Sodium Cocoyl Glutamate, Sodium Lauryl Glucose Carboxylate)
- Hydrolyzed Wheat Protein
- Lamesoft PO65 (Coco-glucoside and Glyceryl Oleate)
- Pearlescent (Glycol Distearate, Laureth-4 and Cocamidopropyl betaine)
- Polyquaternium-7
- Citric Acid
- Fragrance
- Dissolvine GL
The pH of the products was 5.5-5.7.I still plan on using the preservative but was just surprised by the result. -
6 Replies
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It’s surprising knowing that Schulke does Koko test and which runs for 6 weeks AFAIK. Our support lab does a 4 CC test and so comparatively its more stringent. That list has nothing that can support preservation except Dissolvine chelant which boosts the preservative efficacy. Why don’t you contact S&M and send the LOI to them to let them know if there has been a slip during testing. I might be wrong here but honestly I don’t see anything which can protect the formula from a KOKO test.
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The fragrance, depending on composition and concentration, could contribute to preservative efficacy, especially in combination with dissolvine.
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Thanks @Sibech, that is an interesting observation.
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@Chemist77and @Sibechthanks for your thoughts. The fragrance was at low levels so it is probably not the reason for the preservation. I think I will contact Schulke and get their input.
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CAPB and citric acid could act in synergy with the preservatives the rest of the raw materials already have.
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Thanks @DAS . Interesting article.I wonder if the CAPB could be working in conjunction with the disodium cocoamphodiproprionate to give this antimicrobial behaviour. The shampoo sample that I sent previously didn’t contain the disodium cocoamphodiproprionate so could be reason that I see this behaviour for these samples.
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