Photooxidation stability of phytosterols with different relative spatial positions in different particles

Abstract

The aim of this study was to investigate the effects of relative spatial position of stigmasterol on its photooxidation stability in different particles. Phytosterol oxidation products (POPs) from phytosterol oxidation were successfully isolated and studied using solid phase extraction (SPE) technology in conjunction with GC-MS. The photooxidation stability of stigmasterol in four particles was as follows: zein stabilized particles (ZPs) ≈ zein-pectin stabilized particles (ZPPs) > soy protein isolate (SPI)-pectin stabilized particles (SPPs) > SPI stabilized particles (SPs). 7β-Hydroxy and 5β, 6β-epoxy was the main POPs in the first and second oxidation stages, respectively, which reached 8,945 ± 43 μg/g and 6,010 ± 289 μg/g after 240 min UV light exposure treatment in SPs. When stigmasterol was hydrophobically adsorbed on the surface of SPs, the network gel generated by pectin outside SPPs prevented photooxidation of stigmasterol. When stigmasterol was encapsulated in the interior of ZPs, the blocking effect of pectin in ZPPs became insignificant. The study provided a feasible development direction for the storage and quality control of phytosterols as dietary supplements.

Keywords

• phytosterols
• phytosterol oxidation products
• particles
• spatial position
• photooxidation stability