Effect of starch content and ultrasonic pretreatment on gelling properties of myofibrillar protein from Lateolabrax japonicus

Abstract

AbstractTo investigate the protein–starch interactions in myofibrillar protein gels under the ultrasonic pretreatment, the effect of cassava starch content and ultrasonic pretreatment on gelling properties of myofibrillar protein from Lateolabrax japonicus was studied. For the myofibrillar protein–starch (MPS) solutions, the turbidity and elastic modulus increased when the starch content increased from 0% to 8%. For the MPS gels, the hardness, chewiness, gumminess, and water holding capacity increased with the starch content, whereas the cooking loss and whiteness decreased. Starch incorporation promoted the conversion of free water to immobilized water and bound water. The active sulfhydryl content decreased with the starch content, whereas the hydrogen bond and hydrophobic interaction content increased. Fine network structure containing pores at uniform size was formed in the MPS gel at an increased starch content, as shown in the scanning electron microscope images. When the ultrasonic pretreatment was introduced, the elastic modulus of MPS solutions and hardness, chewiness, gumminess, hydrophobic interaction, β‐sheet content, and microstructural compactness of the MPS gels increased, whereas the turbidity of the MPS solutions and cooking loss, whiteness, free water content, active sulfhydryl content, and random coil content of the MPS gels decreased. The MPS gel containing 8% of starch and subjected to ultrasonic pretreatment showed the highest hardness, chewiness, and gumminess of 220, 150, and 160 g, while the lowest cooking loss of 2.5% among all samples. Therefore, the gelling properties of myofibrillar protein from L. japonicus could be enhanced by the starch incorporation, ultrasonic pretreatment, and their synergistic effect.