Physicochemical characterization of commercial zein and particle self-assembly in alkaline pH and high zein concentration in stock solution

Soewardjono, Reyhan Adyatama

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https://hdl.handle.net/2142/125834 Copy

Description

Title

Physicochemical characterization of commercial zein and particle self-assembly in alkaline pH and high zein concentration in stock solution

Author(s)

Soewardjono, Reyhan Adyatama

Issue Date

2024-07-18

Director of Research (if dissertation) or Advisor (if thesis)

Lee, Youngsoo

Committee Member(s)

• de Mejia, Elvira
• Schmidt, Shelly J

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Zein
• High zein concentration
• Nanoparticles
• Antisolvent precipitation
• Characterization

Abstract

Zein, a major storage protein in corn, is capable of self-assembly into various nano and microstructures such as nanoparticles for use in the food and pharmaceutical industries. Zein nanoparticles have been used to encapsulate bioactive compounds to improve their stability and for use in drug-controlled release systems. The antisolvent precipitation method is commonly used to prepare zein nanoparticles due to its low cost and ease of implementation. However, there are challenges associated with preparing zein nanoparticles with the antisolvent precipitation method such as using high concentrations of zein, the type of zein used, pH conditions and the preparation method. This study investigates zein nanoparticle formation of three commercial zein (S1, S2, and FLO) prepared with the antisolvent precipitation method targeting a final zein concentration of 4% w/v using high zein concentration in stock solution (15-23% w/v), and alkaline pH (8, 9, and 10). It was hypothesized that increasing the zein concentration in stock solution and pH will increase particle aggregation and instability, measured by an increase in the particle size, polydispersity index (PDI) and percent aggregation as well as a decrease in the absolute value of zeta potential. Moreover, the physicochemical properties of S1, S2, and FLO zein were characterized to investigate the cause behind FLO zein’s ability and S1 and S2 zeins’ inability to self-assemble into particles in the antisolvent precipitation method when using high zein concentration in the stock solution. It was hypothesized that S1, S2, and FLO zein differ in physicochemical properties, which affect the driving forces in the self-assembly of nanoparticles prepared with the antisolvent precipitation method, using a final zein concentration of 4% w/v, high zein concentration in stock solution (15-23% w/v), and alkaline pH (8, 9, and 10). The goal of this study is to investigate the relationship between zein’s physicochemical properties and zein nanoparticle self-assembly when using high zein concentration in stock solution and alkaline pH. It was found that FLO zein formed micro or nanoparticles while S1 and S2 zein aggregated. FLO zein readily formed nanoparticles at pH 8, 9, and 10 when using a 15 and 17% w/v zein stock solution concentration. When zein stock solution concentration was 19, 21 and 23% w/v, FLO zein aggregated extensively and formed microparticles. FLO zein had a darker yellow color, lower degree of secondary structure in 80% v/v ethanol, higher content of hydrophobic functional groups and lower amount of free SH groups content compared to S1 and S2 zein. These differences influence the hydrophobic forces and disulfide bonding that are vital in the self-assembly of zein into micro or nanoparticles. Therefore, the differences in S1, S2, and FLO zeins’ physicochemical properties explain the differences in their self-assembly into particles in the antisolvent precipitation method when using 15-23% w/v zein concentration in stock solution and alkaline pH of 8, 9, and 10. In the future, investigating the relationship between zein extraction and nanoparticle formation, and a carotenoid content analysis could be done to further understand the effect of different extraction conditions, and the carotenoid content on zein self-assembly mechanisms.

Graduation Semester

2024-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/125834

Copyright and License Information

Copyright 2024 Reyhan Soewardjono

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