Home Cosmetic Science Talk General Challenge test- “no increase” of mold

  • Challenge test- “no increase” of mold

    Posted by Bluebird on June 10, 2023 at 10:04 pm

    USP challenge test, for ex, calls for no increase of Aspergillus in 24 days (or something).

    By “no increase,” hmmm, how strictly do they mean?

    Do they mean no statistically significant increase? Or literally “equal to or less than” before?

    I mean, if you plate out the same exact microbial sample at the same time in replicates, you get slightly different counts of bacteria/mold and that’s what I’m thinking about.

    So say, if your initial count is 1.10 x10^6 CFU/mL and your final count after 24 days is 1.17 x 10^6 CFU/mL, just as an example, that can be an actual increase, OR, more likely, just plating error.

    mikethair replied 5 months, 3 weeks ago 5 Members · 9 Replies
  • 9 Replies
  • mikethair

    June 11, 2023 at 6:13 am

    My approach would always be to have our QC Manager approach your cosmetics compliance authority and seek clarification.

  • philgeis

    June 11, 2023 at 1:00 pm
    It is generally considered that +/- 0.5 logs is no change and this rule is
    included in USP <51> AET.
    • philgeis

      June 11, 2023 at 2:24 pm
      I appeal to you - if your preservative system is so impotent it has no impact on mold inoculum - please please find a more effective system.
      • Richard

        June 12, 2023 at 2:37 am

        100% agree with this comment. You don’t want to find a way to only just pass the test under controlled conditions. You want an effective preservative system that stops any growth from occurring.

      • Bluebird

        June 12, 2023 at 4:55 am

        I plan to use potassium sorbate.

        I was thinking ahead while waiting for Aspergillus to arrive for me to test. 🙂

  • philgeis

    June 12, 2023 at 5:44 am

    What are other preservatives and pH ?

    • Bluebird

      June 12, 2023 at 11:49 pm

      pH of 4-5 (TBD), and the other anti-bacterial parts, also TBD.

  • Porag

    June 13, 2023 at 12:17 am

    Sir,i am new here.thanks a lot to join here me.

    I have a question.

    When i make shampoo and its pH is 5.0 to 5.50,but while i use it my hair fall down.?why please suggest me.

    • mikethair

      June 13, 2023 at 1:36 am

      <div>Hi Porag,</div><div>

      The pH is one of many parameters that may be causing your hair to drop. May I suggest that you provide a list of ingredients for your shampoo formulation. This may provide a clue to your problem.

      Kind regards,


      • This reply was modified 5 months, 3 weeks ago by  mikethair.

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