Effects of hydrocolloids and proteins on dough rheology and in vitro starch digestibility of sweet potato-wheat bread

The improvement of different hydrocolloids (hydroxypropylmethyl cellulose (HPMC), carboxymethylcellulose (CMC), xanthan gum (XG) and apple pectin (AP)) and proteins (egg white protein (EWP), soy protein isolate (SPI), total egg protein (TEP) and whey protein concentrate (WPC)) on the quality of sweet potato-wheat bread (SPWB) from 50% sweet potato flour (SPF) and 50% wheat flour (WF) were investigated. The changes of thermomechanical behaviour, rheological properties, water mobility of dough and in vitro starch digestibility of SPWB were evaluated. XG incorporation significantly increased the peak viscosity (from 259.50 to 1300.67 RVU) and water absorption (from 56.89% to 63.45%) of sweet potato-wheat flour. Dough incorporated with XG showed a homogeneous network structure with immense protein cross-linkages. SPWB with XG exhibited higher specific volume (2.09 ml/g), lower hardness (27.95 N), and expected glycemic index (35.87) as compared to other formulas. XG supplementation could be applied to produce novel SPWB with high quality. •Hydrocolloids and proteins were used for sweet potato-wheat bread (SPWB) making.•Xanthan gum (XG) increased water absorption capacity of flour, followed by HPMC.•Dough incorporated with XG showed a homogeneous network structure.•SPWB with XG showed lower expected glycemic index, followed by SPI, AP, WP and TEP.•XG supplementation could produce novel SPWB with high quality.