Solubility and diffusion of nitrogen in maltodextrin/protein tablets

Area of Science:

• Food science and material science
• Physical chemistry of polymers and amorphous solids

Background:

• Understanding gas transport in amorphous solid matrices is crucial for food processing and packaging.
• Maltodextrin and sodium caseinate mixtures form amorphous matrices with tunable properties.

Purpose of the Study:

• To investigate nitrogen gas transport properties in compacted amorphous maltodextrin-sodium caseinate tablets.
• To determine the influence of temperature, water activity, and processing conditions on gas solubility and release.

Main Methods:

• Dissolving nitrogen gas into tablets under elevated temperature and pressure.
• Measuring gas release over time at various temperatures and water activities.
• Analyzing gas solubility based on matrix free volume and packing density.
• Modeling gas release using Fickian diffusion principles.

Main Results:

• Nitrogen solubility is primarily governed by the free volume of the amorphous matrix.
• Gas release below the glass transition temperature is well-described by Fickian diffusion.
• The effective diffusion coefficient is sensitive to tablet microstructure and porosity.
• A model correlating tablet structure with gas release rate was developed.

Conclusions:

• Thermal and pressure treatments during gas loading influence matrix free volume and nitrogen solubility.
• Gas diffusion in these tablets is predictable using Fickian models below the glass transition temperature.
• The study provides a framework for predicting nitrogen retention in amorphous solid systems.