Product smell and viscosity changed 1 month later

edited July 12 in Formulating
This is my formula. I loved it for the first couple of weeks and now it has a "smell" not a bad smell just as noticeably different smell, almost like vitamin E to it and it's "sticky". It's been in mostly 75 degree weather. Nothing extremely hot or cold. Any ideas why it would start changing after a month? I didn't add a preservative because the pH is at a 3. I did a microbe test when I made it. It's in a dropper bottle. I can retest it for microbial growth if you think that's what happened. 

Lactic

11.11%

Glycerin

2.50%

Sodium lactate

2.50%

Green tea

1.00%

Siligex

1.00% (Xanthan Gum, Lecithin, Sclerotium Gum, Pullulan )


What preservative would you add if you think it needs one? 

Comments

  • chemicalmattchemicalmatt Member, Professional Chemist
    Should not need one at that pH and Aw, but one of the acids e.g. benzoic, sorbic, undecylenic would be appropriate. As for the smell, lactates can smell wonky after a spell, kind of like sweat. Just a hunch, not a certainty. That green tea may not be acid stable also.
  • Siligel is known to smell bad after a while if you don't use a chelator and antioxidant.
  • PharmaPharma Member, Pharmacist
    I observed that with lecithin too (@helenhelen).
    BTW 11% lactic acid does not necessarily keep lactic acid bacteria from growing and it does not keep a bunch of yeast and fungi under control.
  • So I am new at this. At what percentages would you add what to stabilize this formula? Good to know about Siligel changing smell. Maybe I'll just go back to xanthan gum solo. I'll also do a microbial test to see if there's growth now. 

    Thank you. 
  • PattsiPattsi Member
    I don't see benefit of green tea in cosmetics other than for claim don't know about shampoo or hair conditioner. i played with (not professional level i just play with ingredients before i go to formulators) pullulan can become sticky over time don't know why.
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