[talfoa]

I am really sorry but i don’t get the point of performing the AW under humidified conditions. The AW resulted so far (after 24h of conditioning) are 0.08 to 0.13. 
So far i tested:
Solid: Sodium benzoate+chlorphesin+decylene glycol

liquid: Phenoxyethanol, Caprylyl, Glycol Decylene Glycol

[talfoa]

Many thanks Phil for the answer. Yes, the final product is an anhydrous powder. The challenge test is performed by an external lab so i don’t have control on this. To be honest, I am not an expert in the field but the rice starch is theoretically steril and also the external service reported that the product is not contaminated at the start of their analysis. Basically, after they inoculate bacteria and fungi the preservative is not able to reduce them. I added the maximum concentration allowed of the preservatives together with up 2 boosters.

You are right, we already consider the well-known hygroscopicity of rice.

So, now the general question is: How preservatives can act in anhydrous powder? This come from the fact that the corresponding cream formula is protected by the same preservative system tested for powder.

Thank you! 

[talfoa]

Ciao Marina!

I hope you will read this post because I fought with this topic for a long time!

Spirulina is very strong antioxidant…so I thought to add some antioxidant to prevent its oxidation… but it was not possible because the main problem is the thermal stability. I red a lot of paper where it was demonstrated that spirulina is temperature sensitive. Indeed, when you start the stability test…even a simple water solution of spiruline will lost color.

In my case I had to gave up with Blue spiruline…