Correlation Analysis between Moisture and Texture in Muscles of Micropterus salmoides during Fasting Temporary Cultivation

To improve the quality of Micropterus salmoides, eight weeks temporary cultivation were performed under fasting condition. During the period, the back muscles of Micropterus salmoides were taken every week for measuring transverse relaxation time (T₂) and texture characteristics by the low field nuclear magnetic resonance (LF-NMR) and the texture profile analysis (TPA). Then, the water peak area (A) and the peak area proportion (P) were calculated, and the correlation analysis between water and texture indexes was performed. The results showed that the main water of the samples was immobilized water, its peak area proportion P₂₁ could reach more than 95.00%. With the prolongation of the cultivation time, the bound water T_2b decreased in samples. When the Micropterus salmoides was cultured for 6~8 weeks, the free water signals in the samples disappeared and the sum of the P_2b and P₂₁ could reach 100%. Compared with the first week samples, the hardness and chewiness of the samples in 6~8 weeks decreased by 34.34%~42.03% and 18.54%~26.34% respectively, and the resilience and cohesion both increased significantly (P<0.05). On the case of correlation analysis, there was a significant positive correlation among the chewiness, hardness and A₂₂ (P<0.05), and among the cohesion, resilience and T₂₁ (P<0.05). The above result suggested that free water and immobilized water were the main factors affecting the texture of the Micropterus salmoides during the cultivation. And the fasting cultivation of the Micropterus salmoide for 6~8 weeks can enhance the binding force between the fish muscle and the water, and improve the texture characteristics.