Colloidal Colorants: from zein protein to color carrier

Abstract

Color is one of the most important factors that contribute to product appearance. Currently, the safety and consumer acceptance of some colorants used in food products, are under discussion. Therefore, new ways to use natural and renewable colorants as alternatives to these colorants for more applications are investigated. A promising method to increase the applicability for the often-sensitive natural colorants, is the encapsulation of these colorants in colloidal particles by natural polymers. In this thesis we used the vegetable protein zein as a biopolymer. We studied the particle formation and encapsulation properties of zein without added surfactants. First, we only used zein to prepare particles from, which resulted in white dispersions which could be an alternative for the often-used titanium dioxide. Then we co-precipitated anionic dyes together with the zein and found that these two components have high affinity. And finally, we successfully encapsulated the natural colorant lutein into the zein particles, which were found to be more stable when encapsulated. Following this, the optical properties of the resulting colloidal dispersions were studied and compared to light scattering theory in order to investigate whether it is possible to predict the color of such particle dispersions. This was found to be only possible for weakly absorbing dispersions for the tested theory. The scalability of this technique shows the possibility of industrial scale production of fully natural encapsulated particles; which can satisfy the consumers’ wish for natural ingredients, i.e. the natural origin of both encapsulants and colorants.