FAIR-CT96-5070 Improving starch-based films for food packaging: effect of controlled changes in structure during processing on permeability and mechanical properties

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Biopolymers/Gums : FAIR Area 3 - Generic Science and Advanced Technologies for Nutritious Foods : FAIR Marie Curie Research Training Grants : Packaging : Starch

Objectives:

The general aim of this project was to establish a relationship among processing parameters. That is structural characteristics, and oxygen diffusivity and mechanical properties of starch-based films. During the course of the work, most of the time was spent establishing the procedures to study the relationship between molecular structure and oxygen diffusivity.

Activities and Results:

The films were created by casting and drying. Drying kinetics as well as ratio amylose:amylopectin of the potato starch source were used to generate different structures in the starch films. Important points of the film making procedure were:

• no plasticisers were needed to make intact films
• constant shear stress was applied to the starch solution while gelatinisation of the starch granules took place
• solutions were degassed under vacuum after getatinisation
• casting was done on flat plates made of high density polyethylene.

The structure of the films was analysed using various techniques:

• crystallinity and crystal type by X-ray diffraction
• glass transition temperature by differential scanning calorimeter
• molecular conformation by Fourier-transform infrared spectrometry
• phase separation between amylose and amylopectin by light microscopy

In addition oxygen transmission through the films was measured using an Ox-trap apparatus (Modem Control Inc.). Both steady and unsteady-state values from the transmissions were used to obtained oxygen permeability and oxygen diffusivity of the different films.

Conclusions:

The preliminary results seem to indicate that:

1. Both oxygen permeability and oxygen diffusivity were found to be much lower than the values found in the literature.
2. Temperature during drying seems to be a very critical factor affecting structure collapse and film compactness and as a consequence the barrier properties of the films.

Keywords: Starch films, food packaging

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Scientific Supervisor

• ATO NETHERLANDS