With the growing concern of the accumulation of plastic-based food packaging waste, the search for biodegradable packaging materials is on the rise. Over time the structural integrity and function of films and coatings exhibit significant changes due to physical ageing. Luminescent probes, intrinsic or added, have the capability to assess the physical state of the films <i>in situ</i> and can confer molecular level sensing of their local environment. Tyrosine which constitutes an intrinsic probe in our protein based biodegradable films provides <i>in situ</i> information about molecular mobility, with a sharp increase in fluorescence intensity in films stored at low relative humidities as a function of time. Fast Green, an added luminescent molecular rotor, shows a similar pattern to that of tyrosine but higher sensitivity to changes is the molecular environment. Pyranine, an added dual emission solvation probe emits at a lower wavelength when deprotonated and higher wavelength when protonated. The ratio of the two peaks shows apparent changes in drier environments over longer storage periods which builds a dynamic profile of changing film solvation with time. These results when correlated with traditional film mechanical measurements has the potential to assist in the development of more ubiquitous and noninvasive monitoring tool of the stability of biodegradable food packaging  as a function of time.

Brighter side of biodegradable food packaging: Luminescent probes to monitor structural properties

2019 Spring National Meeting

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