Jump to main content
Jump to site search

Issue 15, 2018
Previous Article Next Article

White zein colloidal particles: synthesis and characterization of their optical properties on the single particle level and in concentrated suspensions

Author affiliations

Abstract

Growing interest in using natural, biodegradable ingredients for food products leads to an increase in research for alternative sources of functional ingredients. One alternative is zein, a water-insoluble protein from corn. Here, a method to investigate the optical properties of white zein colloidal particles is presented in both diluted and concentrated suspensions. The particles are synthesized, after purification of zein, by anti-solvent precipitation. Mean particle diameters ranged from 35 to 135 nm based on dynamic light scattering. The value of these particles as white colorant is examined by measuring their optical properties. Dilute suspensions are prepared to measure the extinction cross section of individual particles and this was combined with Mie theory to determine a refractive index (RI) of 1.49 ± 0.01 for zein particles dispersed in water. This value is used to further model the optical properties of concentrated suspensions. To obtain full opacity of the suspension, comparable to 0.1–0.2 wt% suspensions of TiO2, concentrations of 2 to 3.3 wt% of zein particles are sufficient. The optimal size for maximal scattering efficiency is explored by modeling dilute and concentrated samples with RI's matching those of zein and TiO2 particles in water. The transport mean free path of light was determined experimentally and theoretically and the agreement between the transport mean free path calculated from the model and the measured value is better than 30%. Such particles have the potential to be an all-natural edible alternative for TiO2 as white colorant in wet food products.

Graphical abstract: White zein colloidal particles: synthesis and characterization of their optical properties on the single particle level and in concentrated suspensions

Back to tab navigation

Supplementary files

Publication details

The article was received on 08 Dec 2017, accepted on 17 Mar 2018 and first published on 19 Mar 2018


Article type: Paper
DOI: 10.1039/C7SM02415K
Citation: Soft Matter, 2018,14, 2870-2878
  •   Request permissions

    White zein colloidal particles: synthesis and characterization of their optical properties on the single particle level and in concentrated suspensions

    F. Y. de Boer, R. N. U. Kok, A. Imhof and K. P. Velikov, Soft Matter, 2018, 14, 2870
    DOI: 10.1039/C7SM02415K

Search articles by author

Spotlight

Advertisements