Effect of Sexual Maturation on Thermal Stability, Viscoelastic Properties, and Texture of Female Rainbow Trout, Oncorhynchus mykiss, Fillets

The nutrient and energy demand of sexual maturation in many fish cultivars causes structural change to key contractile proteins and thereby, affects fillet firmness. Thermal denaturation and viscoelastic properties of white muscle from diploid (2N; fertile) and triploid (3N; sterile) female rainbow trout were investigated at 6 age endpoints from July 2008 through spawning in March 2009. Differential scanning calorimetry showed, in March, that the actin denaturation temperature (T max,actin) of 2N females was higher than that observed in 3N females (78.17 v. 77.27 degrees C). From 35 to 45 deg C, viscoelastic measurement revealed that muscle from 2N females and younger fish (July, 16 mo) had greater elasticity (lower tan ) than muscle from 3N females and older fish (November-March; 20 -24 mo), respectively. The highest elastic response and the firmest fillets were observed in July. Raw fillets were softer (Allo-Kramer shear; P