Effect of Heat Treatment and Protein Concentration on the Stability and Rheological Properties of Myofibrillar Protein Emulsion

This research was to obtain stable myofibrillar protein emulsion. Myofibrillar protein was extracted from frozen silver carp surimi, and the effects of heat treatment (85 ℃ for 10 min) and protein concentrations (5, 10, 15, 20 and 25 mg/mL) on the aggregation ratio, particle size, zeta-potential and microstructure of myofibrillar protein and structure, apparent viscosity and color of soybean oil-myofibrillar protein emulsion were investigated. The results showed that heat treatment led to the increase of particle size and decrease of apparent viscosity of myofibrillar protein, namely protein aggregation. While emulsion prepared with thermal treated myofibrillar protein displayed high L^* and b^* value and low hydrophobicity. With the increase of myofibrillar protein concentration, the apparent viscosity increased, and the zeta-potential fluctuate increased, no matter the myofibrillar protein solution subjected to heat treatment or not. The minimum particle size of un-heated and heated myofibrillar protein solution was obtained when the protein concentration was 10 and 25 mg/mL, respectively. Besides, the optical microscopy observed that the number of oil droplets involved in emulsification gradually increased, the particle size of oil droplets gradually decreased, the coalescence among oil droplets gradually reduced, when the concentration of myofibrillar protein increased. Therefore, when the protein concentration was in the range of 10~20 mg/mL and the oil ratio was 0.6, the emulsion prepared with thermal treated myofibrillar protein showed high stability and expressed as small and dispersed emulsion droplets and low apparent viscosity. This study is of great significance for the development of stable myofibrillar protein emulsion.