Use of high-intensity ultrasound to improve emulsifying properties of chicken myofibrillar protein and enhance the rheological properties and stability of the emulsion

The effects of high-intensity ultrasound on the emulsifying properties of chicken myofibrillar protein (MP) and the rheological properties and stability of the emulsion stabilized by ultrasound-treated MP were investigated. MP suspensions (0.6 M NaCl) were subjected to ultrasound treatments (frequency 20 kHz, power 450 W, intensity 30 W/cm(2)) for 0, 3 and 6 min. Ultrasound treatment significantly increased (p < 0.05) the emulsion activity index and emulsion stability index of MP and yielded a more stable emulsion. The frequency sweep and temperature sweep of emulsions indicated that ultrasound treatment of MP enhanced the elasticity and viscosity of MP-stabilized emulsion. Ultrasound significantly reduced the particle size of MP (p < 0.05) and promoted the formation of smaller and more uniform emulsion droplets. Ultrasound treatment increased the absorbed protein concentration (p < 0.05), while SDS-PAGE of adsorbed proteins recovered from the emulsion layer showed that the band intensity of myosin heavy chains and actin were increased. Ultrasound significantly increased the unfolding of MP, showing an increase in the reactive sulfhydryl content, surface hydrophobicity and intrinsic fluorescence intensity. Ultrasound significantly reduced (p < 0.05) the alpha-helical content and increased the content of beta-sheet, beta-turn and random coil contents. High-intensity ultrasound induced structural changes in MP and increased interfacial proteins around oil droplets, contributing to an improvement in the emulsifying properties of MP and enhancement in the rheological properties and storage ability of the O/W emulsion. High-intensity ultrasound has important potential for directly enhancing emulsifying characteristics of lean meat proteins on emulsion-type products.