Author(s): Sousa, Vítor Emanuel Silva
Date: 2025
Persistent ID: https://hdl.handle.net/1822/95680
Origin: RepositóriUM - Universidade do Minho
Subject(s): β-carotene; Bioactivities; Dunaliella salina; Downstream and upstream processing; Encapsulation; β-caroteno; Bioatividades; Encapsulação; Processamento a upstream e downstream
The microalga Dunaliella salina has emerged as a promising and sustainable source of β-carotene, a bioactive compound with numerous health benefits and significant industrial applications, particularly in the food and nutraceutical sectors. This thesis explores innovative methodologies to enhance the production, extraction, and bioaccessibility of β-carotene from D. salina, contributing to developing efficient and eco-friendly processes. Optimizing cultivation conditions for D. salina significantly improved biomass and β-carotene production. Through experimental design, salinity (64 PSU), airflow (500 mL.min⁻¹), and nitrate and phosphate concentrations (6 and 0.4 mmol.L⁻¹, respectively) were optimized, resulting in a 88 % increase in β-carotene concentration and a 132 % improvement in biomass yield compared to standard conditions. Further, D. salina and P. gyrans extracts were evaluated for their bioactivity and safety. Both aqueous and ethanolic extracts showed antioxidant, antibacterial, antidiabetic, and antihypertensive activities, with no cytotoxic effects on Caco-2 and BJ5ta cell lines. A sustainable process utilizing ionic liquids (ILs) was developed to recover β-carotene efficiently. This IL-based method achieved β-carotene recovery rates exceeding 84 %. It enabled to sequentially use the IL as an emulsifier for nanoemulsion (NE) production. These NEs demonstrated high entrapment efficiency (100 %), excellent physical stability over 30 days, and improved β-carotene bioaccessibility, reaching up to 92 % under optimal lipid concentrations. Additionally, innovative extraction methods (pressurized liquid extraction) were optimized to recover carotenoids and lipids simultaneously. Using ethanol at 125 °C, 150 MPa, and 3 extraction cycles of 5 min yielded recovery rates of 90.4 % for carotenoids and 80.1 % for lipids. These findings demonstrate the feasibility of integrating sustainable cultivation, extraction, and formulation strategies to enhance the industrial potential of D. salina. By leveraging green technologies and innovative approaches, this work contributes to advancing the microalgae industry as a sustainable source of high-value bioactive compounds.
