Effect of phosphates on gelling characteristics and water mobility of myofibrillar protein from grass carp (Ctenopharyngodon idellus)

Effect of phosphates on the heat-induced gel characteristics of myofibrillar protein (MP) from grass carp was investigated. Both heating and phosphates exerted significant influences. Heating induced more elastic, water-holding and less flowing gel. But phosphates had diverse effects at different temperatures. At 4 °C and 40 °C, phosphate as a dominant factor reduced the gel elasticity and resistance and increased flowability with increasing levels of phosphates. Furthermore, 280 mg/kg sodium pyrophosphate (SPP) or 440 mg/kg sodium triphosphates (STP) transformed MP from weak gel into concentrated solution. It clarified phosphates disentangled MP macromolecules and inhibited their aggregation and pre-gelation at low temperature. At 80 °C, heating accompanied with phosphates governed MP gelation. The appropriate level of phosphates (SPP superior to STP) endowed MP-phosphate gels with the lowest flowability and greatest elasticity, textural properties as well as finest microstructures. Besides, phosphates entrapped a portion of weak immobile water more tightly into smaller-sized pores of protein network.