Is an incubator necessary for microbial testing?

Hello, I would like to purchase a microbial testing kit to test a few of my products, but the instructions require incubating at 35C for a day for bacteria and at 30C for 2 days for fungi. Is an incubator a necessity with these kits? Can an alternative be used - an oven or even leaving out at room temperature for a longer amount of time (I live in the tropics; it is 30C right now at 9pm at night) - or is precision regarding temperature and timing required for accurate results? Thanks.


  • BobzchemistBobzchemist Member, PCF student
    If you are going to sell or even give this product to other people, precision is critically important - the risk of getting a false negative is much too high. If you're just making products for yourself, the risk level is up to you.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • PerryPerry Administrator, Professional Chemist
    Sacrificing product safety to save a little money up front doesn't seem like a good idea. 
  • DavidDavid Member
    If you can record the temperature 24/7 it would be good enough. However, it is easier to buy an incubator. I don't live in the tropics..... but maybe you should also check that the temperature doesn't go to high?
  • Bill_TogeBill_Toge Member, Professional Chemist
    @Perry there are quite a few companies out there who didn't get that memo!
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • Check Product twice or thrice that it won't affect anyone and safe for all. it was not costly to buy an incubator so buy it.
    Blister Packing Machine | Sonus International 
  • I know this is an old discussion but can someone make a recommendation as to where one can purchase an incubator? I'm setting up a lab in my home. Thank you!
  • MarkBroussardMarkBroussard Member, Professional Chemist

    You can purchase a small incubator from Schuelke & Mayr for use with their microbial test strips ... costs about $300 to $400.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details
  • Thanks Mark!
  • As mentioned by @MarkBroussard ;  "You can purchase a small incubator from Schuelke & Mayr for use with their microbial test strips"..... exactly what we have done in our productio  facility. We use the microbial test strips for monitoring of low risk products (just to be 100% sure).
    Dr. Mike Thair
    Cofounder & Chief Formulator
    Indochine Natural
  • Mark's tip led me to eBay where I found one used for $105. Here's one for $115:

    I get my dip slides from Biosan Laboratories. A box of 10 is $49.99. Seems expensive but not sure. 10-testskit

    They also have incubators upwards of 400.00

    Good luck
  • As I understand the question was about the temperature  precision requirements during the test period. For example: what if someone put the test pod into a sterile place where the temperature varies 20C-30C and keep it 3 days instead of  2? Will this work or the tolerance of +-2C is mandatory?
  • You are correct @manuksh about the original question. My approach to this issue is one of compliance and customer safety. If I am facing a GMP inspector, and taking customer safety seriously, the safest route is to follow the manufacturers instructions for the test kit. It would be a weak argument on our side if we didn't in the case of facing a customer compalint or GMP query. 
    Dr. Mike Thair
    Cofounder & Chief Formulator
    Indochine Natural
  • manukshmanuksh Member
    edited July 2017
    I could not find the right answer, but I can link what FDA says for Conventional Plate Count Method :
  • I am confused. So I guess the incubator temperature control high precision is not critical. See what is written in microbiological agar test kit user manual: 25-30C +/- 2C is confusing statement!  
Sign In or Register to comment.