Abstract:The stability of myofibrillar protein solutions and emulsions is affected by ionic strength and heat treatment. To prepare stable myofibrillar protein emulsions, soybean oil-myofibrillar protein solutions and emulsions were prepared to investigate the effect of ionic strength (sodium chloride concentrations: 0.1, 0.3, 0.6 mol/L) and heat treatment (85 ℃, 10 min) on protein composition, particle size distribution, zeta potential, viscosity, and microstructure (as revealed by scanning electron microscopy and optical microscopy). The results showed that the particle size of myofibrillar protein increased with heating owing to aggregation. In heat-treated solutions and emulsions prepared from 0.1 mol/L sodium chloride, the particle size increased from 32 nm to 4 043 nm (in solution), whereas the particle size decreased from 768 nm to 79 nm (in emulsion), indicating an improved stability of myofibrillar protein emulsions. Myofibrillar protein solutions experienced a decrease in apparent viscosity and the absolute value of the zeta potential (from 7.47 mV to 6.72 mV) with increasing ionic strength; however, after heating, the absolute value of the zeta potential increased. In contrast, the absolute value of the zeta potential of emulsions decreased after heating. Heating increased the number of droplets in myofibrillar protein emulsions while reducing droplet size, thus enhancing the dispersity and emulsification activity of droplets and improving the stability of myofibrillar protein emulsions. In conclusion, an ionic strength of 0.6 mol/L, together with heat treatment, resulted in the most stable myofibrillar protein emulsion. This study serves as a reference for the preparation of stable myofibrillar protein emulsions.
