Significant impacts of different types of alginate on the encapsulation stability of fish oil

Author: Zhaolin He

He, Zhaolin, 2019 Significant impacts of different types of alginate on the encapsulation stability of fish oil, Flinders University, College of Medicine and Public Health

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Fish oil exerts remarkable benefits for human health, especially the growth of infants due to its high concentration of omega-3 fatty acids. Sodium alginates have been widely used for as fish oil encapsulation. Recently, the depolymerization technology has shown the ability to reduce the molecular weight and viscosity of alginates to a controllable degree. However, the influence of depolymerized alginate on the encapsulation efficiency and stability of fish oil has not been investigated. Moreover, the sources and types of alginate may also influence the fish oil encapsulation efficiency and stability. The aims of this project were to determine the influence of different types of alginates on the encapsulation efficiency, stability, and beads size distribution of fish oil. In this project, three different sodium alginates, including chemical synthesised alginate, seaweed sourced alginate, and depolymerized alginate from seaweed sourced alginate were investigated in fish oil encapsulation. The SEM results showed that fish oil was still encapsulated by calcium alginate gel bead and provide a more plump and spherical structure than the control group beads prepared without fish oil which had lost the basic bead structure. For the fish oil loading beads, the seaweed sourced alginate had more narrow diameter size distribution than the chemical synthesised alginate and depolymerized alginate from seaweed sourced alginate. The encapsulation efficiency of beads prepared with three alginates showed similar encapsulation efficiency around 97% ~ 98%. After 7 days incubation in petri dish under room temperature, the stability analysis showed that the beads formed by chemical synthesised alginate with higher G (α-L-guluronic acid) residues content had 13.71% oil leakage while the oil leakage of the beads prepared using seaweed sourced alginate was 58.33%. Using the X depolymerized alginate from seaweed sourced alginate, oil leakage was decreased to 28.21%, indicating that 30% oil leakage was reduced. Results indicated that the chemical synthesised alginate with higher G residues formed gel beads with higher encapsulation stability for fish oil than the seaweed sourced alginate with lower G residues. The depolymerized alginate for seaweed sourced alginate with lower molecular and viscosity could improve the bead stability, achieving significant reduction in oil leakage. The main limitation of this study is the limited range of alginates available for the project to establish a full understanding of the impact of different alginate properties including G (α-L-guluronic acid)/M (β-D-mannuronic acid) ratio, molecular weight, and viscosity on the encapsulation of fish oil. Thus, the further research should focus on the parameters of alginate with a range of properties by depolymerization and modification to satisfy the diverse applications in food industry.

Keywords: fish oil, encapsulation, alginate

Subject: Medical Biotechnology thesis

Thesis type: Masters
Completed: 2019
School: College of Medicine and Public Health
Supervisor: Wei Zhang