Tocopheryl acetate release from microcapsules of waxy maize starch

Area of Science:

• Materials Science
• Chemical Engineering
• Biophysics

Background:

• Mass transport phenomena are crucial for delivering bioactivity from high-solid biopolymer systems.
• Diffusion coefficients offer a realistic approach to quantifying these transport processes.
• Understanding these mechanisms is key for optimizing biopolymer-based delivery systems.

Purpose of the Study:

• To produce microcapsules of waxy maize starch encapsulating tocopheryl acetate using spray drying.
• To investigate the relationship between the structural properties of the waxy maize starch network and the diffusivity of tocopheryl acetate.
• To evaluate a modified free-volume theory for predicting molecular diffusion and vitamin-biopolymer interactions.

Main Methods:

• Spray drying was used to create microcapsules of waxy maize starch with suspended tocopheryl acetate.
• A suite of physicochemical techniques (dynamic oscillation, microDSC, WAXD, FTIR, microscopy, UV-vis) were employed.
• A modified free-volume theory was applied and validated over a range of temperatures.

Main Results:

• Physicochemical analyses elucidated the structural properties of the waxy maize starch macromolecular network.
• A mathematical relationship was established between the diffusion coefficient of tocopheryl acetate and the fractional free volume of the starch.
• The theoretical model accurately described the cooperative interactions between vitamin E and the biopolymer, influencing transport kinetics.

Conclusions:

• The study successfully linked the structural characteristics of waxy maize starch microcapsules to the diffusion of tocopheryl acetate.
• A modified free-volume theory provides a predictive framework for understanding molecular diffusion in biopolymer systems.
• This research offers insights into optimizing the delivery of bioactive compounds from biopolymer matrices.