A Reliable Alternative for Traditional Preservative ... - Schülke & Mayr

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M. Leschke, S. Wüstermann
A Reliable Alternative
for Traditional Preservative Systems

COSMETICS
PRESERVATION
M. Leschke, S. Wüstermann*
A Reliable Alternative for Traditional
Preservative Systems
Keywords: cosmetic preservation, enhanced phenoxyethanol, traditional paraben mixtures
Abstract
Cosmetic preservation is increasingly
under pressure. Industry
sensitivity towards the
toxicology of biocides has been
raised. Europe and the U.S. have
started re-evaluating the safety of
cosmetic preservatives. As more
cosmetic manufacturers want to
go »global«, the public debate
around the world regarding traditional
cosmetic preservatives limits
the options available to cosmetic
manufacturers. Cosmetic
formulators are realising the need
for alternative approaches to
product protection. To meet these
market requirements Euxyl ® PE
9010, a new concept in preserving
cosmetics, has been introduced. In
the following article, the antimicrobial
efficacy of Euxyl ® PE 9010
is compared to a traditional
preservative mixture for leave-on
cosmetics.
Introduction
One of the most commonly used preservative
systems for cosmetics are standard
blends of phenoxyethanol and parabens.
25g of each material to be tested
without
preservative
Germ spectrum
Bacteria:
grampositive
Micrococcus luteus
Staphylococcus aureus
gramnegative
Enterobacter gergoviae
Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Pseudomonas fluorescens
Pseudomonas putida
with x %
preservative
Moulds:
Aspergillus niger
Penicillium funiculosum
Yeasts:
Candida albicans
Fig. 1 Evaluation of the microbial stability of cosmetic formulations with the
S&M Koko test
Particularly in leave-on products like
creams and lotions, a blend of methyl-,
propyl-, ethyl-, butyl- and isobutylparaben
in phenoxyethanol is a standard
preservative option (1). Cosmetic chemists
have used this type of system for decades
in the development of »global« formulations.
However, as the list of globallyapproved
preservatives is limited, cosmetic
manufacturers are continually interested
in new alternative preservation
S&M Koko test
periodic microbiological preservation test weekly
inoculation with 0.2 ml mixed suspension
6 weeks = 6 inoculation cycles (titre 10 8-9 cfu/ml)
0.2 ml
storage at +25°C
Streak weekly before each inoculation
on CS- and Sa-Agar
Incubation of the
nutrient media:
3 days at + 25°C
Assessment:
- free of growth
+ slight growth
++ moderate growth
+++ heavy growth
selective identification of
bacteria, yeasts and moulds
systems. Due to this market demand,
preservative suppliers are putting great
efforts in developing alternatives for the
market (2,3). By combining a well-known,
accepted preservative active – phenoxyethanol
– with an innovative, multifunctional
cosmetic additive – ethylhexylglycerin
– the new preservative Euxyl®
PE 9010 is meeting the market requirement
for new preservative concepts (4).
This new preservative has been challenge
2 SÖFW-Journal | 132 | 4-2006

COSMETICS
PRESERVATION
tested in more than 350 different cosmetic
products, both alone and in comparison
studies vs. different traditional
cosmetic preservative systems. These tests
have proven Euxyl® PE 9010 to be an interesting
alternative for cosmetic preservation.
Products tested 44
Products with the same result 40
Products where the paraben mixture is slightly better 2
Products where Euxyl® PE 9010 is slighty better 2
Table 1 Comparison of the efficacy of Euxyl® PE 9010 vs. phenoxyethanol based
paraben mixtures in leave on
Method
Challenge tests have been performed according
to the S&M Koko test method (5,
6) (Fig. 1).
The S&M Koko test is a repeated challenge
test designed and validated by
Schülke & Mayr. A mixed suspension of
Gram-positive and Gram-negative bacteria,
yeast and mould is used for six inoculations
at weekly intervals. Parallel to
each inoculation a sample of the tested
product is streaked out onto nutrient
media, incubated and evaluated semiquantitatively.
The longer the time before
the occurrence of the first microbial
growth, the more effective is the preservative.
Experience has shown that a wellpreserved
product should remain growthfree
for six inoculation cycles to ensure
the shelf-life required in practice (30
months in the original packaging).
Results
The results of the testing done shows
that Euxyl® PE 9010 is most suitable
for the preservation of leave-on cosmet-
Test material/Product
Inoculation Cycles
0 1 2 3 4 5 6
Hand and nail cream, unpreserved -
+++ +++
B,Y,M B,Y,M
./.
+ 1.0 % paraben mixture * - - - - - - -
+ 1.0 % Euxyl® PE 9010 - - - - - - -
LV Sun spray, unpreserved
++ +++ +++
-
B,Y,M B,Y,M B,Y,M
./.
++ ++ +++ +++
+ 0.5 % paraben mixture *
-
Y Y Y B,Y
./.
+ 1.0 % paraben mixture * - - - - - - -
+ 0.5 % Euxyl® PE 9010
-
++ ++ +++ +++
Y Y Y B,Y
./.
+ 1.0 % Euxyl® PE 9010 - - - - - - -
Fragrance free dry skin Cream, - ++ +++ +++
unpreserved B,Y,M B,Y,M B,Y,M
./.
+ 1.0 % paraben mixture *
+ 1.0 % Euxyl® PE 9010
-
-
+
+
++
+
++
+
+
+
+
+
+
+
B
B
B
B
B
B
B
B
B
B
B
B
O Sterility control - free of microbial growth
B Bacteria + slight growth
M Moulds ++ moderate growth
Y Yeast +++ massive growth
Fig. 2 Comparison of the efficacy of Euxyl® PE 9010 vs. a traditional paraben mixture during six inoculation cycles
(* methyl-, ethyl-, propyl-, butyl- and isobutylparaben in phenoxyethanol)
SÖFW-Journal | 132 | 4-2006 3

COSMETICS
PRESERVATION
ics such as creams, lotions, wet wipes,
hair care and hair styling products. For
these products one of the market-leading
preservative systems is the combination
of methyl-, propyl-, ethyl-, butyland
isobutylparaben in phenoxyethanol.
To study the efficacy of the combination
of phenoxyethanol and the preservative
enhancer ethylhexylglycerin vs. traditional
phenoxyethanol/paraben mixtures, S&M
Koko tests were performed. The results
are impressive. 40 out of the 44 products
tested showed the same challenge test
result whether preserved with Euxyl® PE
9010 or the paraben mixture (Table 1).
Slight differences in the efficacy between
the two systems could be observed in only
4 products.
Based on the main application area for
paraben mixtures – leave-on products –
90 % of the products tested show nearly
identical results in preservative efficacy
for the traditional paraben mixture
and Euxyl® PE 9010. If the paraben blend
passed the test Euxyl® PE 9010 passed also
and vice versa. If the paraben mixture
was not effective in preserving a cosmetic
formulation the enhanced phenoxyethanol
failed as well.
The comparable efficacies of the traditional
paraben mixture and Euxyl® PE
9010 is shown for different customer
products (Fig. 2).
Discussion
As all three examples – a hand and nail
cream, a sun spray and a fragrance free
dry skin cream – show, the challenge
tests have the same test characteristics
irrespective of whether the preservative
is a paraben mixture or Euxyl® PE 9010.
While the hand and nail cream and the
sun spray stay well preserved during six
inoculation cycles with 1.0 % of the
paraben mixture as well as 1.0 % Euxyl®
PE 9010, the fragrance free dry skin
cream shows slight growth of bacteria
during the entire challenge test with
both preservatives.
The test results show that Euxyl® PE 9010
is as effective as a traditional phenoxyethanol/paraben
mixture when
used at equivalent concentrations. It is
recommended to check the stability and
preservative efficacy in individual cosmetic
products as any change in the
preservative system may affect the performance
of the formulation.
Conclusion
Due to ongoing discussions regarding
preservative actives, formulators are increasingly
looking for new options. With
Euxyl® PE 9010 a reliable alternative to
the commonly used phenoxyethanolbased
paraben mixtures was introduced.
As proven in several challenge tests, it is
particularly effective for the preservation
of leave-on cosmetics, such as
creams, lotions, wet wipes, hair care and
styling products. This new preservative
system has been proven effective in almost
every product where the standard
paraben mixture is effective and it is an
alternative to classical preservative
blends.
References
(1) D. Steinberg, Preservatives for Cosmetics, Second
Edition, 31, Allured Publishing Corporation,
Carol Stream, USA (2006), 11 – 14
(2) M.S. Reisch, Chemical & Engeneering News, 2005,
Nov. 14, 25 – 27
(3) D. de Guzman, Chemical Market Reporter, 2005,
Vol. 268, 19, Dec. 5 – 18, 20 – 22
(4) W. Beilfuss, M. Leschke, K. Weber, SÖFW-Journal
2005,11,30 – 36
(5) K. Weber, J. Siebert, SÖFW-Journal, 2003, 6, 44
– 50 (English); 48 – 55 (German)
(6) W. Siegert, Cosmetic Science Technology, 2005,
189 – 195
* Authors’ address:
Dr. Marion Leschke
Silke Wüstermann
Schülke & Mayr GmbH
Special Additive International
22840 Norderstedt
Germany
Mailto: sai@schuelke-mayr.com
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