Scattering and absorption of nanoparticles made of zein

Abstract

Customers expect most food products to have a certain color, which makes the use of colorants necessary. However, the available set of food colorants is quite limiting, making it difficult to obtain a certain color while avoiding solubility and chemical stability issues. One way to circumvent these issues is by encapsulating the colorant in other (food-safe) chemicals. This thesis focuses on encapsulation of colorants inside nanoparticles made of zein. Zein is a collection of hydrophobic storage proteins from corn that, because of its mostly hydrophobic solubility behavior, is well-suited for the synthesis of nanoparticles.

In this thesis, white and colored zein particles with average sizes from 40 to 150 nm were synthesized in water. To gain more insight in the scattering and absorption properties of the samples, modeling was used. For white particles in dilute suspensions, the scattering efficiencies were successfully modeled using Mie theory, taking into account the experimental size distributions. For colored particles, the model was extended to include absorption. Finally, another approach, based on light diffusion theory, was also used to model the scattering and absorption of concentrated samples.