Comparison of extraction process, physicochemical properties, and in vitro digestion characteristics of chia seed mucilage polysaccharide.

The study explored five (acidic, alkaline, heating, ionic liquid, and urea solvent) extraction methods' effects on chia seed mucilage polysaccharide (CSM), an anionic polymeric macromolecule, regarding its physicochemical properties, structure, and digestion behavior. The results showed that extraction parameters have a considerable effect on modulating CSM properties. Significant differences emerged in the predominant chemical compositions: the carbohydrates and protein content ranged from 49.20±0.06 % to 85.81±0.03 %, and 3.20±0.13 % to 14.57±0.30 %, respectively. The structural analysis revealed that alkaline heating treatment facilitated the formation of protein-polysaccharide conjugates, resulting in reduced particle size, enhanced ζ-potential, and improved thermal stability (194.72±2.19 J/g). The crystallinity of CSM varied, peaking at 42.9±0.22 % without pH adjustment and heating. CSM extracted using 6 M urea exhibited the lowest protein content, and crystallinity (25.50±0.09 %), coupled with the highest gastrointestinal digestion rate and poorest thermal stability (with a carbohydrate degradability of 24.223±1.78 % and enthalpy value of 62.82±0.32 J/g). The CSM obtained under alkaline heating showed minute particles (201.1±10.35 μm), the highest ζ-potential absolute value (20.95±2.28 mV), and robust thermal stability (194.72±2.19 J/g of enthalpy value), which is ideal for stabilizing emulsions or encapsulating thermolabile substances. Additionally, compared to monovalent cations‑sodium ions, divalent cations‑magnesium ions, is more tend to aggregate the CSM structure, resulting in larger molecular particles and a higher protein content. Elevated ionic concentration further diminished thermal stability. These findings suggest that CSM is a customizable, multi-purpose polymer that can be extracted in various ways based on the end-product requirements.