Abstract: The aim of this study was to explore the mechanism of the effect of acyl transfer taking place during the enzymatic
hydrolysis of phospholipid on the interaction between soybean protein isolate (SPI) and phospholipid hydrolysates as well as
emulsion stability and storage stability by the combined use of nuclear magnetic resonance (NMR) spectroscopy and threedimensional
fluorescence spectroscopy. The results showed that among four samples, i.e., SPI alone and its complexes with
lecithin (Lec) and lecithin hydrolysates at 4 and 8 h of hydrolysis, which were designated as SPI, SPI-Lec, SPI-Lec4h and
SPI-Lec8h, respectively, the SPI-Lec4h sample had the best emulsion stability and storage stability. However, the SPI-Lec8h
sample was not as good, due to the occurrence of acyl transfer that resulted in the transformation of lysophospholipids to
glyceryl-phosphorylcholine to weaken the interaction between SPI and phospholipid hydrolysate. Therefore, the addition
of suitable enzymatic hydrolysates of phospholipid to SPI emulsions will improve the emulsifying properties through the
formation of a stable interfacial film, promoted by the interaction between them.

Key words: soybean protein isolate (SPI), phospholipase hydrolysate, acyl transfer, interaction, emulsifying properties