Spray-dried soy protein/tamarind seed polysaccharide/tea polyphenol ternary complexes with enzymatic and natural crosslinking enhance probiotic viability

To enhance probiotic survival during spray drying, a ternary encapsulation matrix composed of soy protein isolate, tamarind seed polysaccharide, and tea polyphenol was constructed and reinforced via enzymatic (transglutaminase/laccase) or chemical (genipin) cross-linking. The system relies on synergistic non-covalent interactions and covalent densification. The results showed that cross-linking significantly enhanced colloidal stability, with transglutaminase-treated complexes exhibiting the highest absolute ζ potential (−21.01 mV). Notably, the genipin-crosslinked capsules offered superior gastric protection with minimal viability loss (0.78 log CFU/g), whereas the laccase-crosslinked capsules facilitated intestinal-targeted release. During 28 days of storage at 25 °C, the cross-linked systems maintained high viability (6.28–6.95 log CFU/g) due to the synergistic barrier effect and sustained antioxidant activity, significantly outperforming free cells. This study demonstrated that cross-linked ternary complexes provide a robust, tunable platform for stabilized probiotic delivery in functional foods.