Tea polyphenols-OSA starch interaction and its impact on interface properties and oxidative stability of O/W emulsion

In this study, octenyl succinic anhydride-modified starch (OSA starch) and tea polyphenols (TP S ) complexes (OS-TPs) were prepared, and their effects on the physical and oxidative stability of oil-water emulsion as well as the interaction mechanism were investigated. OS-TPs complex reduced the oil-water interfacial tension to 9.44 mN/m as the concentration of TPs increased to 0.75% (w/w) and improved the emulsifying ability of OSA starch. Compared with a simple mixture of tea polyphenols and OSA starch emulsion, the emulsion prepared by the OS-TPs complexes had higher oxidative stability, with a peroxide value of only 1.45 meq/kg after 40 days of storage when the concentration of TPs reached 0.75% (w/w). The decomposition temperature of the OS-TPs complex increased to 312.98 °C at maximum, indicating a more stable structure of the complex. Hydrophobic fluorescence analysis and Fourier transform infrared proved the interaction between OSA starch and TP S . Isothermal titration calorimetry analysis further confirmed that hydrogen binding and hydrophobic interaction were involved between OSA starch and (−)-epigallocatechin-3-gallate (EGCG), which is the main component of TPs. • Oil-water interfacial tension decreased as TPs incorporated with OSA starch. • Emulsion formed with OS-TPs complex had higher physical and oxidative stability. • OS-TPs complex had higher decomposition temperature. • Hydrogen bond and hydrophobic interaction existed between TPs and OSA starch.