Novel polysaccharide/polysaccharide complex microgels stabilized HIPEs formed by carboxymethyl tamarind seed polysaccharide and chitosan for improved stability and bioaccessibility of curcumin

In this work, Pickering emulsions, stabilized with carboxymethyl tamarind seed polysaccharide/chitosan (CMTSP/CS) complex microgels, were formulated with oil-phase ratios of 60% and 80% and encapsulating curcumin. The stability and in vitro digestive characteristics were systematically investigated. High internal phase emulsions (HIPEs) with 80% oil phase demonstrated superior storage stability and improved oxidative stability. SAOS and LAOS analysis further revealed that the HIPEs stabilized by CMTSP/CS complex microgels at 1:1 ratio exhibited the highest viscoelastic property and greatest deformation resistance. Increasing the mass ratio of CMTSP to CS from 1:5 to 1:1 formed a more stable interfacial film of emulsion droplets with superior viscoelastic properties, resulting in higher centrifugal resistance and thermal stability. The Pickering emulsion (particularly HIPEs at 1:1) showed reduced curcumin degradation and higher retention rates. Lipid digestion kinetics revealed that the HIPEs at 1:1 achieved maximal free fatty acid release and the highest curcumin bioaccessibility. The system exhibited an increased electrostatic repulsion and highest viscoelastic film properties, which effectively mitigated oil droplet aggregation. It facilitated the release of free fatty acids and promoted the formation of additional mixed micelles, thereby improving the bioaccessibility of curcumin. • HIPEs stabilized by CMTSP/CS complex microgels demonstrated enhanced storage, centrifugal, thermal and improved oxidative stability. • HIPEs stabilized by CMTSP/CS complex microgels exhibited best viscoelastic property and great deformation resistance. • HIPEs stabilized by CMTSP/CS complex microgels at 1:1 presented strongest curcumin retention rate. • HIPEs at 1:1 showed the highest release of FFA and the highest bioaccessibility of curcumin.