Effect of sodium trimetaphosphate on the physicochemical properties of modified soy protein isolates and its lutein‐loaded emulsion

Abstract

Due to people's pursuit of healthy and green life, soy protein isolate (SPI) is occupying a larger and larger market share. However, the low solubility of SPI affects its development in the field of food and medicine. This paper aimed to investigate the effects of sodium trimetaphosphate (STMP) on the functional properties and structures of phosphorylated SPI and its lutein-loaded emulsion. After modification by STMP, the phosphorus content of phosphorylated SPI reached 1.2-3.61 mg/g. Infrared spectrum and X-ray photoelectron spectrum analysis confirmed that PO 4 3− had phosphorylation with -OH in serine of SPI molecule. X-ray diffraction analysis showed that phosphorylation destroyed the crystal structure of protein molecules. Zeta potential value of phosphorylated SPI decreased significantly. When STMP addition was 100 g/kg, particle size of protein solution decreased to 203 nm, and solubility increased to 73.5%. Furthermore, emulsifying activity and emulsifying stability increased by 0.51 times and 8 times, respectively. At the same protein concentration (1%-3% [w/w]), lutein-loaded emulsion prepared by phosphorylated SPI had higher absolute potential and smaller particle size. The phosphorylated protein emulsion at 2% concentration had the best emulsion stability after storage for 17 days.

Soy protein isolate with higher solubility and improved gel properties when co‐assembled with walnut protein

“…The most frequently employed of these is chemical modification. Dextran grafting and phosphorylation treatments have been demonstrated to boost the solubility of SPI to 46% and 73% respectively (Boostani et al ., 2017; Lu et al ., 2023). However, phosphorylation and glycosylation treatments often introduce extra functional groups, which may pose potential safety hazards.…”