March 2019

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
• 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 [email protected] if interested. Thanks for your interest and I’ll see you April. SPRAY

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  link