2.5.1 Measurement of oil viscosity
The rheological properties of walnut butter were measured based on a previous method (Mostafa et al., 2019). The viscosity of the oil was determined using a DHR 2 rheometer (Waters, USA). Experimental conditions: an aluminum plate of 60 mm with a taper of 1.007° was selected, plate spacing was set to 500 μm, the temperature was set to 25°C, and the frequency variation range was set to 1 - 100 s-1.