The future brings with it the ever increasing need to supply fresh and safe foods to the world’s population. There is also an increasing consumer demand for naturally-derived food-packaging products that produce minimal environmental impacts during their production and ultimate disposal to landfill. These realities have led to the search for novel active packaging systems based on natural resources that incorporate new materials that are not derived from the traditional petroleum-based sources but instead are derived from renewable sources such as biopolymers. Composites comprised of the renewable biopolymer poly(lactic acid) (PLA) filled with kenaf, a natural fibre, have been assessed in our laboratory in the context of their potential use as antimicrobial (AM) food-packaging materials. It has been found that the incorporation of the kenaf fibres enhances the physicomechanical properties of the PLA and its presence as a filler will also reduce the overall cost of the material. This paper discusses the latest work performed in our laboratory on the formulation and characterization of potential AM packaging systems comprised of PLA/kenaf and the natural AM agent thymol. The optimization of the performance of these materials with particular respect to controlling the release of the AM agent from the composite matrix will also be discussed. Differential scanning calorimetric measurements along with a novel approach to thermogravimetric analysis were used to characterize the interaction between the composite matrix and the AM agent and hence better understand the factors that influence the release of the AM agent from the matrix. The application of the long-established technique of non-isothermal thermogravimetric kinetic analysis is re-visited in the form of a novel computer-based iterative numerical method that was developed to process the experimental kinetic data by executing an integral approach. This advanced method enables the activation energies and Arrhenius factor parameters for these systems to be obtained without having to invoke the usual simplifying assumptions in solving the kinetic expressions. This is achieved via an algorithm that calculates from the experimental data a set of parameters that can be compared to corresponding characteristic parameters that pertain to a wide range of known kinetic models that were calculated theoretically in an independent study.

Advanced thermal analysis modelling for the characterization of active poly(lactic acid)/natural fibre food-packaging composite materials

253rd National Meeting (2017)

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