Effect of Hydrophilic and Lipophilic Compounds on Zein Microstructures

Abstract

Zein, the prolamine of corn, contains nearly an equal amount of hydrophilic and lipophilic amino acid residues. Its tertiary structure has a regular geometry measuring 17×4.5×1.2 nm. The structure of zein allows it to function as a polymeric amphiphile. Zein had been observed to self-assemble into periodic bilayer structures and nanotubes. This work investigated the structural development of zein self-assemblies as affected by the hydrophilic-lipophilic balance (HLB) of the system. The formation of several structures, including spheres, sponge, and lamellae, were identified. Images were obtained by SEM, AFM, and FIB/SEM. The radius of curvature of the observed assemblies was affected by the HLB of the components in the system. Thus, lipophilic flavor oils increased the curvature of zein spheres producing smaller spheres. Curvature decreased in the presence of amphiphilic fatty acids forming sponges with interconnected channels.Hydrophilic compounds decreased the curvature to the point of forming smooth films. The results of this study see a future in microencapsulation and controlled release systems for flavor and bioactive compounds in the food industry.

Improvement in Water Stability and Other Related Functional Properties of Thin Cast Kafirin Protein Films

“…These films had a rough surface and the microparticles were poorly fused (arrows, Figure 2A-g, h), which was similar to the appearance of biomaterials made from zein microparticles such as films (22)(23) and sponges (24). Previous work has shown that films prepared from microwave-heated kafirin had a rough surface, which was attributed to Taylor (34) reported a reduction in α-helical conformation when they studied the protein secondary structure in cooked kafirin.…”

Development of flexible zein–wax composite and zein–fatty acid blend films for controlled release of lysozyme

“…According to these authors the morphological changes in zein-oleic acid system occurred at three steps; (1) formation of large numbers of oleic acid coated zein spheres, (2) partial melting of the spheres by means of oleic acid, and (3) transformation of a sponge like morphology by interconnection of spheres with channels and tunnels. The spheres observed by SEM of zein-oleic acid films in this work lacked the interconnections specified by Wang et al (2008). Thus, it seemed that the lecithin emulsifier used in this work stabilized the oleic acid coating formed around zein spheres.…”

“…Thus, it seemed that the lecithin emulsifier used in this work stabilized the oleic acid coating formed around zein spheres. It appears that the repulsion formed by negative charges of lecithin at the oleic acid coating of formed zein spheres prevented the interaction and melting down of these spheres which formed the sponge-like structure described by Wang et al (2008). Thus, it appeared that the reduced release rates of lysozyme in catechin containing zein-oleic acid blend films are in part due to the entrapment of lysozyme within spherical capsules which increased the barriers against enzyme diffusion.…”

“…2H shows that the addition of oleic acid into zein films caused formation of many spherical capsules within films. The morphological changes of zein structure when it is mixed with oleic acid without use of lecithin emulsifier was recently explained by Wang, Yin, and Padua (2008). According to these authors the morphological changes in zein-oleic acid system occurred at three steps; (1) formation of large numbers of oleic acid coated zein spheres, (2) partial melting of the spheres by means of oleic acid, and (3) transformation of a sponge like morphology by interconnection of spheres with channels and tunnels.…”

Selective Interactions of Zein Microspheres with Different Class of Drugs: An In Vitro and In Silico Analysis

“…Wang et al (10) investigated the effect of various hydrophilic and lipophilic compounds on zein aggregation and selfassembly. This study revealed that lipophilic compounds increased the curvature of zein and thereby resulting in the development of smaller spherical particles.…”