Degree Type

Dissertation

Date of Award

2020

Degree Name

Master of Science

Department

Food Science and Human Nutrition

Major

Food Science and Technology

First Advisor

Nuria C Acevedo

Abstract

Starch nanoparticles (SNPs) and Chitin nanofibers (ChFs) have high potential to be used as an environmentally-friendly solution for future sustainable applications in many fields, such as foods, pharmaceuticals, and cosmetics. This work aims to evaluate the efficiency of combining both solid nanoparticles, SNPs and ChFs to stabilize o/w Pickering emulsions as well as to study the protective effect that the formulated Pickering emulsion systems exert on encapsulated bioactive ingredients such as curcumin. SNPs were prepared by a non-solvent precipitation method followed by octenyl succinic anhydride (OSA) modification, whereas ChFs were produced by acid hydrolysis. The effect of sonication on emulsion preparation was investigated by comparing the characteristics of emulsions prepared with and without sonication.

Regardless of the nanoparticles used as stabilizers, sonicated emulsions were composed of significantly smaller droplet sizes compared to the non-sonicated emulsions. On the other hand, SNP/ChF-stabilized Pickering emulsions showed smaller droplet sizes than those stabilized by either type of nanoparticles. The combination of both nanoparticles resulted in emulsions with higher stability over storage time and wider ranges of temperature and pH than emulsions stabilized by only one type of nanoparticle. These observations suggested a synergistic effect on emulsion stabilization played by the combination of both particles. The addition of NaCl had a partial positive impact on the emulsions' stability, with a maximum effect at a concentration of 200 mM. The results showed that Pickering emulsions' overall stability could be improved by using a combination of both solid particles.

Different SNP/ChF concentrations were used to evaluate the protective effect of the emulsion systems on the stability of encapsulated curcumin in excess water, over storage and under UV exposure. The results showed that more than 45% of curcumin was retained under different conditions. Doubling the concentration of either solid nanoparticles did not significantly improve the protective effect of the emulsion system. Instead, it was found that the protective effect of SNP/ChF-stabilized Pickering emulsions can be significantly improved when the concentrations of both solid nanoparticles were increased, reaching optimal concentrations at 0.4% ChFs and 2% SNPs (C4S2 emulsion). The degradation kinetics of curcumin over storage time and under UV exposure were found to follow first-order kinetics. Furthermore, when emulsions were stabilized by C4S2 combination, lipid oxidation was reduced and the shelf life was extended to longer than 60 days (AV<10). The combined use of both SNPs and ChFs seems to be a promising approach to improve emulsion stability and it can potentially be used as a vehicle to deliver bioactive ingredients with high efficiency.

DOI

https://doi.org/10.31274/etd-20210114-79

Copyright Owner

Yeong Sheng Lee

Language

en

File Format

application/pdf

File Size

116 pages

Available for download on Friday, January 07, 2022

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