Impact of advanced extraction technologies and characterization of freeze-dried brown seaweed polysaccharides

The main objective of the study is to evaluate the extraction efficiency methods followed by freeze-drying of bioactive brown seaweed polysaccharides (BSPs). Brown seaweeds such as Sargassum wightii, Spatoglossum asperum, Colpomenia sinuosa, Padina tetrastromatica were considered in this study. Conventional solvent extraction (CSE), and advanced extraction techniques such as microwave-aided (MAE), ultrasound-aided (UAE), and enzyme-aided extractions (EAE) were attempted. MAE (2.5 GHz, 15 min) and UAE (50-60 kHz, 30 min) require minimum time and found to be thermal effective compared to the CSE method. EAE exhibited the maximal extraction efficiency of BSPs and S. wightii shown high polysaccharide content (54.99%). The antioxidant activity of all the extracted polysaccharides was evaluated and found to be maximum with P. tetrastromatica. Prebiotic activity assays were attempted on all EAE polysaccharides. Based on antioxidant and prebiotic activity, enzyme-assisted P. tetrastromatica extract was chosen to study for its characteristics using sophisticated analytical techniques. This study signifies the intertwined characteristics of antioxidant properties and shelf life along with its prebiotic activity of freeze-dried bioactive compounds for its desired purpose as a functional ingredient.