Effects of Microfluidization on the Physical and Storage Stability of Walnut Protein Emulsion and Beverages

Walnut meal is a by-product produced during the production of walnut oil and is often treated as a waste. However, the nutrients in walnut meal mean it has significant potential for development as a plant-based milk. This study investigated the effect of microfluidization on the stability of walnut protein emulsion (WPE) and walnut protein beverage (WPB) produced from walnut meal, compared with conventional homogenization. The particle size, zeta potential, rheological properties, and stability of WPE all significantly improved after microfluidization. The mean particle size and zeta potential of the microfluidized WPE significantly decreased (p < 0.05). The rheological properties demonstrated that the viscosity of the microfluidized WPE decreased by 80%, and that the shear force increased 4.5 times as the shear rate increased. This gave the resulting product the characteristics of non-Newtonian fluid. LUMisizer stability demonstrated that microfluidization improves stability through protein absorption on the oil-water interface. Microfluidization increased the denaturation temperature (Tm) of WPE from 135.65 to 154.87℃. Moreover, microfluidization improved the color, centrifugal precipitation rate, and viscosity in WPB compared to the control at all studied temperatures. The Arrhenius approach was used to establish a shelf-life model, which predicted that microfluidized WPB could be stored for 175 d at 4℃. This study provided a new reference for the widespread application of microfluidization in the production of food-based emulsion and beverage products.