2.5. Texture profile analysis (TPA)

The TPA could obtain the texture characteristic parameters related to human sensory evaluation. Before performing the analysis, ducks’ breasts were packaged in vacuum bags, heated at 80℃ for 40 min (TW20, JULABO, Germany), and then carved to hexahedron (1 cm × 1 cm × 1 cm). The TPA was performed according to the method of Feng et al., (²⁰¹⁷) with slight modifications. Hardness, springiness, cohesiveness, and chewiness of samples were determined at 25℃ with a cylindrical probe (P/50) of the texture analyzer (TA‐XT2i, Stable Micro System). The conditions were as follows: (1) 50% strain; (2) both pretest speed and test speed were adjusted to 2.0 mm/s; (3) post‐test speed was adjusted to 5.0 mm/s. It is worthy of noticing that two presses against each sample could result in two peaks. The parameters that were measured for TPA were the following: hardness (Hd) = peak force (N) required for first compression; chewiness (Cw) = Hd × Ch × Sp (N × mm); cohesiveness (Ch) = ratio of active work done under the second compression curve to that done under the first compression curve (dimensionless); springiness (Sp) = distance (mm) the sample recovers after the first compression.