PhD Defence by Elnaz Z. Fallahasghari

Principal supervisor:

• Professor Ioannis S. Chronakis

Co-supervisor:

• Associate Professor Ana Carina Loureiro Mendes

Examiners:

• Associate Professor Aberham Hailu Feyissa, DTU-Food
• Professor Tommy Nylander, Department of Chemistry, Lund University, Sweden
• Associate Professor Mingshi Yang, Department of Pharmacy, University of Copenhagen, Denmark

Chairperson at defence:

• Senior Researcher Heidi Amlund

Resume
Lipophilic compounds, such as vitamin A and omega-3-rich fish oil, play crucial roles in our health. Vitamin A is vital for vision and immune function, while omega-3 fatty acids support heart health. However, nutrient deficiencies remain a global issue, particularly in developing countries, and low omega-3 consumption is linked to chronic diseases. As awareness of their health benefits grows, the food industry is increasingly focused on developing products enriched with these essential compounds. Both vitamin A and fish oil are highly susceptible to oxidation, which can diminish their nutritional value and taste.

This PhD project explored innovative electrohydrodynamic techniques, specifically electrospraying, to create nano- and microcapsules that protect these sensitive compounds.

Plant-based proteins (kafirin and zein) and polysaccharides (modified starch and ethyl cellulose) were assessed for their encapsulation efficiency and ability to enhance oxidative stability using both monoaxial and coaxial electrospraying techniques. The effects of various excipients, including soy protein hydrolysate, casein protein hydrolysate, lecithin, digestion-resistant maltodextrin, and different amino acids, were also assessed.

Innovatively, ethanol was utilized as a solvent in the core, facilitating contact with the lipophilic compounds and dispersing the aforementioned excipients. This approach offers a novel alternative to conventional solvents typically used in core polymer formulations, aiming to minimize or prevent oxidation during processing.

The oxidative stability of the encapsulated compounds was assessed using various techniques, including Raman spectroscopy, Electron Paramagnetic Resonance (EPR), and Differential Scanning Calorimetry (DSCA new protocol for assessing oxidative stability was developed using the isothermal DSC method, offering a more straightforward and efficient measurement compared to alternative techniques, such as Raman spectroscopy (which necessitates decapsulation), Electron Paramagnetic Resonance (EPR).

The findings reveal that coaxial electrospraying, a method emphasized in this research, produces microcapsules that effectively protect fish oil and vitamin A from oxidation. Incorporating the oxidative protective compound in the nano-microcapsule formulations further improved the oxidative stability of the core-shell structured microcapsules. Notably, formulations incorporating casein protein hydrolysate and histidine significantly improved the oxidative stability of coaxially produced vitamin A microcapsules.