Soluble soybean polysaccharide-zinc chelate: physicochemical, biological, capsule characterization

SSPS-Zn chelate was synthesized by soluble soybean polysaccharide (SSPS) and zinc chloride, and its properties were investigated in this paper. SSPS-Zn was easily soluble in deionized water, but not easily soluble in acetone, chloroform and n -butanol at room temperature. The water content and swelling index of SSPS-Zn were 5.52% and 185.00%, respectively. SSPS-Zn also showed good colloidal stability in the pH range of 1–14. In 0–10 mg/mL concentration range, SSPS-Zn exhibited markedly improvement for all four in vitro antioxidant activities (DPPH, •OH, and O 2 ⁻• scavenging, and lipid peroxidation inhibition). SSPS-Zn demonstrated stronger inhibitory effects on α -glucosidase and α -amylase, and superior urea adsorption ability, implying the potential to lower blood sugar and urea toxicity. The SSPS-Zn capsule preparation process was optimized using Response Surface Design. The quadratic polynomial regression model for the yield of capsule granule intermediates was established. The optimal conditions included an ethanol concentration of 77.60%, an MCC content of 38.88%, and a drying temperature of 51.50 °C, achieving a granulation yield of 91.02%. The SSPS-Zn capsules exhibited favorable physicochemical properties, with a repose angle below 30°, an average bulk density of 0.92 g/mL, an average moisture content of 6.22 ± 0.15%, and a critical relative humidity of approximately 66%. Under simulated gastrointestinal conditions, the Zn 2+ release rate reached approximately 41.66% after 40 min, 65.74% after 2 h, and 70.83% after 3 h, indicating a sustainable release behavior. These characteristics suggested that SSPS-Zn capsules have potential as multifunctional organic zinc supplements with antioxidant, hypoglycemic, and detoxifying properties.