Overview of alginate extraction processes: Impact on alginate molecular structure and techno-functional properties

Background: Brown algae are a valuable source of various biopolymers, with alginate standing out as a phycocolloid of great industrial importance. Although the extraction process is well established on an industrial scale, several innovative and environmentally friendly extraction technologies have been explored to improve the efficiency of the process both in terms of yields and energy and solvent consumption. Scope and approach: The review aims to describe and analyze different strategies used to extract alginate from brown algae, including different pre-treatment methods used before extraction. In addition, the impact of these extraction technologies, with or without pre-treatments, on alginate's structural and techno-functional properties is also discussed. Key findings: The extraction process parameters play a key role and significantly influence the quality of alginate and the extraction yield. Innovative technologies have the potential to enhance extraction capacity, improve process efficiency, and promote environmental friendliness. Research efforts are focused on achieving sustainable alginate production and co-production of other value-added products. This review provides useful information to the alginate industry towards a more sustainable approach and foster the diversification of high-value products.The authors wish to acknowledge funds from the project PID2020-117744RJ-I00 and grant CEX2021-001189-S funded by MCIN/AEI/10.13039/501100011033 and the project CIRCALGAE (Horizon Europe) under grant agreement 101060607. H. Bojorges acknowledges financial support from the Generalitat Valenciana for the award of a Santiago Grisolía grant (GRISOLIAP/2019/007).With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX 2021-001189-S)Peer reviewe