Corrosion Corner
Probiotics & Spray
Package MIC
Hello, everyone. There have recently
been several articles and editorials
about probiotics in spray formulas
(see the editorial in the December 2018
issue of SPRAY).
If you haven’t been following articles
about probiotics, they are benign bacteria
and yeast. Medical research on probiotics
indicates that they might improve gastrointestinal
health and recent research on cosmetic
and personal care products indicates
that probiotics might also contribute to
skin and oral health.
I’ve included information at the bottom
of this column for a review paper on probiotics
in personal care products. This paper
was written by researchers at the U.S. Food
& Drug Administration (FDA) and Noblis,
Inc. and has numerous citations for other
probiotics technical papers.
Probiotics and spray package corrosion
What do probiotics have to do with spray package corrosion?
Notice the title for this column ends with “MIC.” MIC is the
acronym Microbial Induced Corrosion; this is a complex type of
metal corrosion caused by microbial colony deposits on uncoated
metal and coated metal surfaces.
MIC is typically very rare in spray packaging. Indeed, I’ve only
seen a few instances of MIC (for
formulas without probiotics) that
caused spray package failures
(perforations). The main attributes
of MIC are:
• MIC-causing microbes are
believed to be attracted by the
electrical fields generated
around metal grain boundaries
• MIC-causing microbes have sizes around the width and
depth of metal grain boundaries, making the grain
boundaries prime sites for microbes to attach on surfaces
and subsequently grow colonies
W. Stephen tait, ph.D.
Chief Science Officer & principal Consultant,
pair O Docs professionals, LLC
• The metabolic wastes produced by
MIC-causing microbes are organic acids,
such as lactic acid and hyaluronic acid,
that are electrochemically active and
thus could contribute to or cause spray
package metal corrosion
• Human skin is a polymer coating and
microbes (plus their metabolic waste)
that modify human skin will also modify
polymer coatings and laminate films
Consequently, probiotics could contribute
to or cause package metal and
polymer corrosion, such as MIC.
It is always exciting when a new
product technology is found for spray
packaging. However, research on the probiotic
medical benefits for personal care
products is still in its early stages.
There are also technical issues with
probiotics in spray packages that need
to be resolved, such as what the effective concentrations for
the various types of microbes are and how to keep the various
types of microbes alive in spray packages, particularly with
formulas incorporating biocides that prevent growth of harmful
microbes.
Probiotics are not always expected to contribute to or cause
spray package corrosion. However, corrosion testing with these
types of formulas is essential because
probiotics could contribute
to or cause spray package MIC
with subsequent package failure.
In other words, as with all spray
formulas, I recommend being
diligent and conducting spray
package corrosion testing.
We plan to drive from Wisconsin
to California and back for two weeks from late April–early
May 2019. Consequently, Pair O Docs would be pleased to
teach our Elements of Spray Package Corrosion short course at
your company if you are located west of Wisconsin (north or
south route). Please contact me at 608-831-2076 or rustdr@
pairodocspro.com if interested. Thanks for your interest and I’ll
see you April. Spray
32 Spray March 2019
Microbial Induced Corrosion (MIC)
is a complex type of metal
corrosion caused by microbial
colony deposits on uncoated metal
and coated metal surfaces…
Review paper on Probiotics in Personal Care Products
• Mei-Chiung Jo Huang & Jane Tang, Microbiology Discovery, Volume 3, Article 5, 2015, Herbert
Open Access Journals
www.hoajonline.com/journals/pdf/2052-6180-3-5.pdf