Date of Award

1-1-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Food Science

First Advisor

YUAN YAO

Committee Member 1

ARUN BHUNIA

Committee Member 2

JAMES DANIEL

Committee Member 3

FERNANDA SAN MARTIN

Abstract

The food processing industry has focused on using conventional methods for food preservation. However, the recurring incidence of food borne illnesses and outbreaks due to pathogenic or spoilage organisms have called for creation of novel intervention strategies. In recent years, antimicrobial compounds from natural sources are gaining significant importance in improving food safety and security. However, antimicrobials suffer from extensive degradation when applied to complex food systems due to several specific or non-specific interactions. There is an urgent need for the protection of such antimicrobials to prolong their activity in foods. One strategy of achieving the goal is by the combination with a delivery vehicle. In this work, we explored the interaction between novel carbohydrate biomaterial and model antimicrobial compounds. In addition, we studied the protection of such antimicrobials using carbohydrate based colloidal systems. In the first part, we examine the interactions between nisin and carbohydrate based materials in non-emulsion (aqueous) and emulsion systems. Phytoglycogen octenyl succinate (PG-OS), a dendrimer-like amphiphilic material was used as the model carbohydrate nanoparticle and nisin was used as the model antimicrobial peptide. Equilibrium dialysis experiments showed that PG-OS with different degree of substitution (DS) interacts with nisin in a Langmuir monolayer adsorption pattern in both non-emulsion and emulsion systems. The monolayer adsorption capacity (Qm) increased in non-emulsion system and was significantly higher in the emulsion system. At the equivalent concentration of PG-OS (5.0 mg/mL), and nisin (200 µg/mL), adsorbed nisin concentration in aqueous and emulsion systems were 22 and 157 µg/mL, respectively. The study demonstrated that DS of PG-OS can be used to control nisin adsorption in the non-emulsion system. In addition, the distribution of PG-OS at the droplet interface affects nisin adsorption in the emulsion system.

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