Evaluating the effect of protein modifications and water distribution on bitterness and adhesiveness of Jinhua ham

•Defective ham showed an intense denaturation in sarcoplasmic proteins and actin.•Denaturation and shifts of α-helix to β-sheets were key modifications of muscle proteins.•Immobile water was responsible for excessive softness and adhesiveness of ham.•PLSR confirmed protein modifications and water distribution were related to bitterness and adhesiveness. Defects with textures and flavors are a common problem, causing many economic losses in the dry-cured ham industry. To obtain a better understanding of the defects of dry-cured ham, texture, protein denaturation, protein structure, and water distribution of normal and defective hams were investigated. Compared with normal ham, more than 1.5-fold values in adhesiveness and bitterness, and less than 0.8-fold values in hardness were found in defective ham. The intense denaturation of sarcoplasmic proteins and actin, and the dramatic transformation of α-helix to β-sheet were the key modification of proteins; a high proportion (92.39%) of immobile water contributed to the excessive softness and adhesiveness of defective hams. Furthermore, high denaturation of proteins could accelerate the degradation of proteins, which further developed the bitterness and adhesiveness of defective hams. Partial least squares regression demonstrated that the discrepancies in protein denaturation, protein structure and water distribution were related with bitterness and adhesiveness of Jinhua ham.