Fabrication and characterization of Pickering emulsion gels stabilized by gliadin/starch complex for the delivery of astaxanthin

Abstract

Pickering emulsion gels (PEGs) are structured emulsions that have demonstrated their advantages in the delivery of bioactive compounds since the gel network inhibits droplet coalescence, Ostwald ripening, and phase separation. Herein, the gliadin/starch nanocomposites (G/SNPs) with distinct gliadin/starch ratios were prepared and used to stabilize the PEGs. The interaction between gliadin and gelatinized starch was confirmed by fluorescence and Fourier transform infrared (FTIR) spectra. The presence of gelatinized starch improved the wettability of G/SNPs. The maximum three-phase contact angle was 84° when the ratio of gliadin/starch was 1:5 (G/SNPs 1:5). The appearance, micromorphology, oil droplet size distribution, and rheological properties suggested that stable PEGs stabilized by G/SNPs were formed. The PEGs stabilized by G/SNPs 1:5 were stable for at least one year when stored at room temperature. The super stability of PEGs was related to the compact three-dimensional network structure. Moreover, PEGs were stable at pH values ranging from 3 to 11 and tolerated high ionic strength up to 1000 mmol L−1 NaCl. Furthermore, the retention rate of astaxanthin in the G/SNPs 1:5 stabilized PEGs was improved since the half-life of encapsulated astaxanthin was 2.3 times longer than that in oil. In addition, in vitro digestion suggested the bioaccessibility of astaxanthin in PEGs was 1.5 times higher than that of oil. Taken together, these results indicated that G/SNPs stabilized PEGs were promising carriers for the better delivery of hydrophobic bioactive compounds.