Enhancing gluten-free dough and bread properties using xanthan gum and its trifluoroacetic acid hydrolytes

This study investigated the effects of xanthan gum with varying molecular structures on the properties of glutenfree dough and bread, focusing on its potential to improve the quality of gluten-free bread. The xanthan gum was hydrolyzed using trifluoroacetic acid (TFA) to produce hydrolytes of different molecular weights: unhydrolyzed xanthan gum: (3.0 x 107 Da), medium molecular weight (1.7 x 107 Da), low molecular weight (8.2 x 106 Da). TFA hydrolysis reduced the branching degree of xanthan gum from 42.29 % to 27.99 %, primarily by hydrolyzing the side chains of pyruvate and acetyl groups, in which the terminal mannose residues were more susceptible to degradation. Compared with the dough without xanthan, the addition of xanthan gum significantly enhanced dough height after proofing, increasing from 2.55 cm to 5.60 cm, 6.75 cm and 6.80 cm for unhydrolyzed xanthan gum (HMX), medium molecular weight xanthan gum (MMX) and low molecular weight xanthan gum (LMX), respectively. As compared to HMX, MMX addition increased the bread's specific volume and reduced the hardness and gumminess of gluten-free bread. Breads with HMX or LMX exhibited lower specific volume and higher hardness than breads with MMX, suggesting that the MMX was more beneficial for enhancing the structural and sensory properties of gluten-free bread. These findings provided theoretical basis on improving the quality of gluten-free bread with suitable molecular weight hydrocolloids.