The effect of fat on properties and filling characteristics of myofibrillar protein emulsion microgels

Emulsion microgels are micron-sized particles formed by one or more emulsion droplets surrounded by soft solids. It is inferred that their special structure affords interesting filling properties in protein gels. Different fat types affect the properties of emulsion microgels leading to different filling effects. The influence of fat types (soybean oil, lard, and coconut oil) on the myofibrillar protein emulsion microgels was studied by particle size, microstructure, and rheology. The filling properties were investigated in a protein gel model. The results show that coconut oil emulsion microgels had the smallest particle size, the thickest gel shell and the highest storage modulus. The apparent viscosity of all treatments showed shear thinning behavior and that of coconut oil treatment was significantly higher. With the increase in fat contents, the thixotropic ring area of coconut oil and lard treatment increased, while that of soybean oil treatment decreased. The filling properties in the protein gel model were analyzed by rheology, texture, microstructure and cooking loss measurement. Adding emulsion microgels to pure gels could increase the storage modulus of gels, and the storage modulus of gels filled with coconut oil emulsion microgels was the highest, indicating that emulsion microgels were active fillers. When the amount of addition was more than 10%, the texture properties of the filled gels improved, which was attributed to the enhanced density of the microstructure. In addition, the cooking loss was also reduced, and the gels filled with coconut oil emulsion microgels had the best performance.