Abstract: In order to reveal the protective mechanism of hydrocolloid on wheat dough gluten during freezing, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to investigate the secondary structure, microstructure, disulfide bond content and water-binding capacity of gluten obtained from frozen-thawed wheat dough added with different amounts of flaxseed gum (FG) or Artemisia sphaerocephala Krasch. gum (ASKG). Results showed that freezing-thawing treatment destroyed the ordered network structure of gluten, while FG and ASKG could cross-link with the gluten protein network structure to form a stable cross-linked structure. Upon the addition of FG or ASKG at 0.4%, the gluten network structure was most uniform and dense. The addition of FG and ASKG increased the content of disulfide bond and the relative content of α-helix in gluten, making the gluten structure more stable under repeated freeze-thaw cycles. In addition, the addition of FG and ASKG reduced the surface hydrophobicity and consequently led to an increase in the water-binding capacity of wheat gluten. The highest water-binding capacity was obtained at an addition level of 0.4% for both FG and ASKG, 1.46 and 1.43 times higher than that of the control group without added hydrocolloid undergoing repeated freeze-thaw cycles, respectively. All these results showed that FG and ASKG could interact with gluten to form a stable cross-linked structure, thereby enhancing the water binding capacity of gluten protein and exerting a cryoprotective effect on it.

Key words: freezing-thawing treatment; gluten structure; flaxseed gum; Artemisia sphaerocephala Krasch. gum