Preparation and characterisation of soy protein isolated particle film homogenised at different pressures

Summary The aim of this article was to study the effect of homogenisation pressure on the microstructure of soy protein isolated (SPI) particles, the size of SPI particles and the properties of SPI particle films. Particle films were prepared by homogenising SPI particles at different pressures (0, 60, 70, 80, 90 and 100 MPa), and their optical properties, water resistance and mechanical properties were investigated. With increasing homogenisation pressure, the particle size of SPI decreased from 5123 to 295.7 nm, more homogeneous and compact network structures with good integrity were gradually constructed, and α‐helices and β‐turns transited to β‐sheets and random coils. Compared to natural SPI films, the opacity value and swelling ratio of SPI particle films were reduced by 48% and 31%, respectively, and the mechanical properties increased by 47% at 90 MPa. This study offered a theoretical basis for the application of protein particle films.