Scientific publication Spotlight

We all want more time to read a scientific publication, in our domain of expertise or even broader. Probably we even missed some interesting ones. I’ll take periodically the time to read through “an article” and briefly summarize what I deem interesting, allowing you to decide yourselves to deep-dive or not into that article.

Some years ago, I did an academic literature search and came across some interesting articles on the migration of polymer additives through the polymeric material. It’s interesting reading material because the worlds of physics, chemistry and mathematics come together when one tries to predict the behavior though modelling with an experimental check. And that’s really what Science is all about !

The article described below is dealing with PolyPropylene, one of the most used polymers in packaging, both in the food industry and in pharmaceutical packaging. It’s also a common material in certain types of Medical Devices.

Brief summary and notes

The polymer additives under study are butylated hydroxytoluene (BHT) and pentaerythritol tetrakismethylene-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) (commercial and commonly used name : Irganox 1010), both are part of the additives list in the respective monographs (E.P. 3.1.3 and USP 661.1).

Hence they’re often encountered in Extractables and Leachables studies (pharma and medical device chemical characterization) and in food contact studies to claim safety in the latter domain. Their selection and associated relevance is clear.

This article describes the mathematical modelling for the migration of these two additives into selected mixtures of ethanol and water, simulating food contact. The models are then checked versus experimentally established data, the latter are obtained with HPLC-DAD analysis.

One of the interesting aspects of this research is both the fundamental approach and the various conditions investigated.

The fundamental part logically relies in the application of the well-known equation, namely Fick’s second law on the mass transfer between two phases in unsteady conditions with parameters like the diffusion coefficient D and/or the partition coefficient Kp.

Conditions of storage applied in this study are autoclave heating, microwave heating and freezer storage, obviously mimicking? various levels of energy provided and hence different interactions, reactions and outcomes. One can make a link with other levels of energy, like sterilization by EtO or NOx, by gamma radiation, or an elevated temperature during storage or transport.

Conclusions/comments

Diffusion coefficients were determined for both additives under study in four conditions (control, autoclave heating, microwave radiation and freezer storage) with various simulant solutions (95% / 50 % / 10% ethanol in water) whereby the obtained values were the same in the different solution mixtures.

Obviously, and in line with the general understanding of diffusion and migration, the diffusion coefficient was the highest in the PP films subjected to autoclave heating and the lowest after freeze storage (it’s all about the ability to move). This trend was identical for BHT and for Irganox 1010.

And again, logical and in line, Irganox 1010 showed in the same conditions a smaller diffusion coefficient (as larger species are moving slower and more difficult).

In general the mathematical models and their outcome are quite good in predicting the actual migration and should perhaps be more used as a predictive tool or even a replacement of some studies, to be discussed….

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From the article (italic)

Therefore, the mathematical calculations predicted migration values higher than those obtained from the experiments. That is, theoretically predicted data does not exactly reflect the actual migration values. Overall, the mathematical migration model offers reliable prediction of migration behaviors without the need for experiments. Because the calculations assume worst-case migration conditions, foods for which the estimated migrant concentrations are lower than the upper regulatory limits would be suitable for human consumption.

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Reference:

Experimental and theoretical study of polypropylene: Antioxidant migration with different food simulants and temperatures

Yoonjee Changa, Kyungmo Kang, Se-Jong Park, Jae Chun Choi, MeeKyung Kim, Jaejoon Han

Journal of Food Engineering, 244, 2019, 142-149

#BHT #irganox1010 #foodsafety #Fick #migration #modelling #extractable #leachable #HPLC #diffusion #partition

James Stern Jesper Laursen Mike Freudenstein Anja Gottschalk Johan Jaubin Hannes De Vos Emily Brown Aryo Nikopour Paulo Forte Lilla Mezriczky Aaron DeMent Dania Cortes Alpa Patel Thor Rollins Audrey Turley Michelle Lee Fran?ois B.