2.6 Microrheological characterization
The microrheological properties were determined with reference to a previous method (Mengjie et al., 2021). The microrheological properties of walnut butter were investigated using a microrheometer (Rheolaser Master, France). The freshly prepared walnut butter was placed in a 4 mL cylindrical glass tube to observe the Brownian Motion of the particles. The setting time was 4 h, and the temperature was 25°C. The changes in the mean square displacement (MSD) curve, the elasticity index (EI), solid-liquid balance index (SLB), and the flow index (FI) of the sample particles were recorded using Rheosoft Master software 1.4.0.0 software. The elasticity index (EI), solid-liquid balance index (SLB), and the flow index (FI) were obtained from the mean square displacement (MSD) curves. EI was the inverse of the height value of the plateau zone in the MSD curve. SLB was the slope value of the elastic plateau zone of the MSD curve. FI was the inverse of the characteristic decorrelation time corresponding to the decorrelation time required to reach the correlated scatter plot (Fernandes and Salas Mellado, 2018).