January 23, 2012 at 12:45 pm #15974pi87Participant
I’m wondering whether bacteria and fungi can be present or can grow in drysol: an antiperspirant consisting of absolute ethanol and aluminum chloride hexahydrate. We got some results from a rather unserious foreign lab:
Bacteria testing: sampling made 1:10 test liquid. In 80 Twain agar, 38°C，foster 48 hours.
Results: < 1000 (cfu/g)
Yeast & mold test: sampling made 1: 10 test liquid. In Tiger red AGAR, 28 °C foster 72 hours.
Results: < 100 (cfu/g)
Can these results be right? Can anything survive in these environments?
January 23, 2012 at 12:50 pm #109153JackBeanParticipant
well, 0 < 1000 😉
January 23, 2012 at 8:26 pm #109162canalonParticipant
And to add to Jackbean’s answer since they did not plate a full gram of sample, they have to limit their results to the lower limit they could detect reliably, hence the <1000 rather than 0
January 24, 2012 at 10:47 am #109167pi87Participant
If "no pathogens" are present, must this number be 0?
January 24, 2012 at 11:11 am #109168JackBeanParticipant
it will hardly be <0 and if it is >0, then there is some growth 😉
However, it’s always kind of probability numbers, especially for low counts. That’s probably also reason, why they do not clearly state 0 cfu/g, but rather give some limit.
January 24, 2012 at 7:42 pm #109176canalonParticipant
No you can never be sure that it is absolutely 0, so you just say that it is below your detection limit. Which is good enough.
January 25, 2012 at 12:10 am #109179michimichiParticipant
we dont report 0 as a result, The value <100 or <1000 means the sample was diluted.
it is synonymous to 0. or you can say "absent or negative" if you are only pertaining to quality.
January 25, 2012 at 1:10 am #109181JorgeLoboParticipant
It’s hard to know what pi87 is asking as the report offers no confdence anything was detected. Agree th 1:10 dilution cited doesn;t seem consistent with the <1000 report. My bet is the diluton factor is stated incorrectly as substantial dilution is necessary to neutralize product carryover. Although one can recover spore forming bacteria and even vegetative bacteria (in biofilm) from ethanol, antiperspirant aluminum Cl salt renders the product very acidic so it’s pretty hostile and would require a fair amount of dilution to neutralize.
January 25, 2012 at 2:34 am #109182michimichiParticipant
mostly no microorganism can survive in that environment specially those susceptible or"weak microorganisms".but yes, a spored microorganisms can may survive . cosmetics can be contaminated (mostly yeast and molds) after production, during filling, packaging, the way they handle the cosmetic.Obviously they grow only on the surface of the cosmetic as an indication of contamination.
That is why we use the antimicrobial efficacy test/challenge test to determine the efficacy of its preservative.
January 25, 2012 at 3:03 am #109183JorgeLoboParticipant
No – the most common contaminants of cosmetics are bacterial – esp. is Burkholderia cepacia and grow throughout the product. Contamination is most frequently associated with water – poor quality process water or cleaning water such as from failed draining of systems after washoutincubating in equipment inclding those mentioned.
Mold contamination is a relatively rare event in comparison. It is typically limited to the surface of semiolid cosmetics in open jars and is probably as much a consumer as manufacturing issue – so is pretty obvious when it does occur. Yeast contamaintion is also somewhat rare and is not surface limited.
The AET is useful but not insurances. Cosmetic micro quality is as much a function of process hygiene as preservation as bacteria can adapt/ develop tolerance and resistance to any preservative given the right opprtunity.
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