Permeation of volatile compounds through starch films

Area of Science:

• Food Science and Technology
• Materials Science
• Polymer Science

Background:

• Starch films are promising biodegradable materials.
• Controlling their properties, like barrier performance, is crucial for applications.
• Factors influencing volatile permeation through starch films require detailed investigation.

Purpose of the Study:

• To investigate factors affecting volatile permeation through starch films.
• To understand the relationship between film structure (crystallinity, water, glycerol content) and diffusion coefficients.
• To analyze the diffusion behavior of carvone and diacetyl in starch films.

Main Methods:

• Starch films prepared by casting gelatinized starch/water/glycerol mixtures.
• Films dried and conditioned to vary crystallinity and composition.
• Permeation analyzed gravimetrically for carvone and diacetyl at different relative humidities (RH).
• Solubility of volatiles determined under experimental conditions.
• Diffusion coefficients calculated from permeation and solubility data.

Main Results:

• Increased film water content correlated with higher glycerol and RH during preparation/conditioning.
• Diacetyl exhibited higher flux than carvone across films of similar composition.
• Volatile solubility showed slight dependence on film properties.
• Diffusion coefficients decreased with increasing starch crystallinity.
• Free volume model effectively described diffusion in films with similar crystallinity, with water and glycerol as key determinants.

Conclusions:

• Starch film crystallinity acts as a barrier to volatile diffusion.
• Water and glycerol content plasticize the starch matrix, increasing free volume and thus diffusion.
• The free volume model provides a framework for understanding volatile transport in starch-based materials.
• Findings offer insights for designing starch films with tailored barrier properties.