The investigation of the changes in physicochemical, texture and rheological characteristics of salted duck egg yolk during salting

The relationships between the maturation of salted duck egg yolk and the changes of physicochemical, texture and rheological properties were investigated by instrumental analyses. For the physicochemical properties, the apparent oil yield rate and oil extraction rate of salted duck egg yolk respectively increased during salting. The surface hydrophobicity also had an increasing trend and achieved a maximum value of 96.961S(0), however, the particle size and zeta potential had significant decrement because of the protein accumulation. For texture, the parameters of hardness (858.91-2396.46 N), adhesiveness (2.64-5.11 Ns), springiness (0.28-0.43 mm), gumminess (352.34-918.29 N), and chewiness (139.39-417.45 N) had prominent increases during salting, while cohesiveness had a reverse trend. For the rheological characteristics, the gelatinization of yolk caused by salt resulted in the increments of elastic and viscous modulus. These significant alterations on yolk indicated that the micro-structure of yolk protein had changes that induced by NaCl in the process of curing. The equilibriums of three properties achieved during 20-25 days salting implied the maturation of salted duck egg yolk. Meanwhile, the composition and polypeptide chains of yolk did not degrade or aggregate during salting according to the gel electrophoresis.