Effects of ionic polysaccharides and egg white protein complex formulations on dough rheological properties, structure formation and in vitro starch digestibility of wet sweet potato vermicelli.

Effects of ionic polysaccharides [chitosan (C), sodium alginate (A) and xanthan (X)] and egg white protein (EP) complex formulations on dough rheology, structure formation and in vitro starch digestibility of wet sweet potato vermicelli (SPV) were investigated. Linear viscoelastic region (LVR) with low strain level of 0.015-0.036% were observed for all starch doughs with different complex formulations. Starch doughs complexed with A-X, C-EP, A-EP and X-EP exhibited lower degree of dependence of G' on frequency sweep and maximum creep compliance in creep-recovery test, followed by those with C-A-EP and A-X-EP, suggesting stable network structure formation. Wet SPV with C-A exhibited the strongest tensile strength (1.99 g/mm2), followed by those with C-EP and C-A-EP (1.51 and 1.58 g/mm2), and all showed high tensile distance (91.00%, 77.92% and 66.91%) and cooking break time (46.0, 45.5 and 48.5 min) respectively. Evenly distributed air cells with smaller pore sizes were formed, and compacted patterns of starch molecules were presented in all wet SPV with different complex formulations. Wet SPV with C-A-EP showed lower rapidly digestible (31.42%) but higher resistant starch (61.59%) content compared to other formulations. Thus, complex formulations of C-A, C-EP and C-A-EP show great application potential in wet SPV with high quality.