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Document Type

Campus-Only Access for One (1) Year

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2019

Month Degree Awarded

May

First Advisor

David Julian McClements

Subject Categories

Food Chemistry

Abstract

In current studies, hydrogel particles were formed by polysaccharides (i.e., alginate or pectin) and protein (i.e., casein or gelatin) through complex coacervation. Our results indicated that the encapsulation of protein or polyunsaturated lipid droplets nanoparticles within the hydrogel particles could improve their chemical or physical stability during storage. The lipid droplets encapsulated within the hydrogel particles could be released under simulated oral conditions, which was triggered by a pH or temperature change. The current study further fabricated the hydrogel particles (beads) using alginate or carrageenan based on an injection-gelation method. We found carrageenan beads had a relatively fragile structure that was easily disrupted in the GIT and released the encapsulated lipid droplets and curcumin. Conversely, alginate beads had a robust structure that remained relatively intact throughout the GIT and retained the lipid droplets and curcumin. The incorporation of the β-carotene-loaded lipid droplets into hydrogel beads greatly improved its chemical stability during storage and digestion process. The current study further fabricated the hydrogel beads with self-regulating internal pH microclimates by encapsulating antacid agents (i.e., Mg(OH)2or CaCO3) inside them. A quantitative fluorescence confocal laser scanning microscopy (CLSM) method was developed to map the local pH inside the hydrogel beads. Our results showed that the pH inside antacid-loaded beads remained close to neutral in the mouth and stomach, leading to retention the activity of acid sensitive agents (i.e., lactase, lipase, insulin and probiotics) in the small intestine. The current study further studied the effect of pH on the encapsulation, retention and release of whey proteins from alginate-based hydrogel beads. Our results indicated that the protein encapsulation efficiency and retention of the beads increased with decreasing fabrication pH, which was attributed to the fact that there was a strong electrostatic attraction between the cationic protein and anionic beads matrix (alginate molecules) at low pH conditions. Overall, our study suggest that hydrogel particles with different structures and compositions can be designed for encapsulation, protection, and delivery of hydrophilic or lipophilic bioactive agents, which is advantageous for the development of certain functional food products.

Available for download on Sunday, November 10, 2019

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