Preparation of aqueous alpha-lipoic acid dispersions with octenylsuccinylated high amylose starch

Aqueous dispersions prepared with OSA-modified high amylose starch were investigated in comparison with native high amylose starch and beta-cyclodextrin using alpha-lipoic acid as a model substance. Alpha-lipoic acid (ALA), a lipophilic antioxidant essential for energy metabolism in human, was dispersed in gelatinized starch solutions (1.0% w/v) at different temperatures (50-90 °C) and times (3-12 h). High amylose starch modified with 3% OSA (dry starch base) was most favored in maximizing the dispersibility of ALA (84% recovery) under mild heating (70 °C for 3 h). The optimally prepared dispersion was milky white and contained particles with a narrow size distribution (200-300 nm). The precipitate isolated from the dispersion contained crystalline V-complexes of ALA and amylose while the supernatant contained free ALA accounting for 1/3 of total ALA, indicating OSA-modified high amylose starch stabilized ALA either by complexing with amylose or by retarding aggregation of ALA.