Gelation properties and protein conformation of grass carp fish ball as influenced by egg white protein

Abstract Dried egg white powder (EWP) and purified ovalbumin (OVA, 98%) were used as supplements to improve grass carp (GC) fish balls (FB) quality. The effects of EWP and/or OVA contents on the gel strength, water holding capacity (WHC), moisture migration and distribution, and rheological properties of GC‐FB, as well as on myofibrillar protein (MfP) structures in the GC‐FB were evaluated. The results showed that with the increase of EWP addition from 0 to 4% (w/w), the gel strength, and WHC of the GC‐FB samples were increased from 34.28 to 66.63 N × mm, and 83.02 to 88.36%, respectively, but the increases were insignificant between 3 and 4% EWP‐added GC‐FBs ( p > .05). As the EWP increased, the T 2 relaxation time shifted toward lower values, indicating a general decline in water mobility. The effects of EWP on rheological properties were insignificant. Addition of OVA and/or EWP led to changes in secondary structural units in the FB, with α‐helix (27.53%) reaching the highest value in OVA‐added GC‐FB, β‐sheet (46.07%) reaching the highest value in GC‐FB, and β‐turn (33.54%) reaching the highest value in EWP‐added GC‐FB, respectively. Raman spectroscopy revealed that OVA‐added GC‐FB had the lowest hydrophobic interlinkages. Protein pattern analysis suggested that the OVA (1.58%) might contribute to the decrease in the myosin heavy chain band intensity through cross‐linked with MfP. These results suggested that EWP could improve the quality of GC‐FBs and OVA played an important role with MfP gelation.