Comparative study on extraction procedures for polysaccharides from safflower post-extraction residue: Structural characterization and bioactivity evaluation

The purpose of this study was to valorize safflower post-extraction residue by comparing the structure characterization, function characteristics, and bioactivity of four safflower polysaccharides (SPSs: HWES, UAES, HES, AES) extracted via different procedures. AES showed the highest yield (1.59 ± 0.01 %) and polysaccharides content (92.07 ± 0.09 %). SPSs had molecular weights of 256.46–404.38 kDa, UAES had the best water holding capacity (2.55 ± 0.14 g/g), HES had the best foaming stability (82.89 ± 0.38 %). SPSs all exhibited shear-thinning behavior, with HES showing the highest viscosity and prominent viscous liquid-like characteristics. AES had small particle size and high thermal stability and the best foaming capacity (214.52 ± 8.74 %) and emulsification activity index (5.14 ± 0.04 m 2 /g), and displayed optimal antioxidant activity and immunomodulatory effect. These findings established the isolation procedures for safflower post-extraction residue polysaccharides, identified AE procedure as the most viable approach for producing industrially relevant bioactive SPSs, and provided a practical strategy for enhancing the utilization of safflower residue. • Alkaline extraction maximizes safflower polysaccharide yield (1.59 ± 0.006 %) and bioactivity. • AES exhibits superior antioxidant (ABTS: 93.66 ± 1.64 %) and immunomodulatory effects. • Structural features (Ara and Glc) correlate with enhanced bioactivity. • Safflower post-extraction residues are repurposed as a sustainable source of functional polysaccharides.