Physical quality and in vitro starch digestibility of bread as affected by addition of extracted malva nut gum

- Extracted malva nut gum (MNG) inhibited α-amylase activity in solid matrix.
- SEM analysis revealed undigested starch granules of MNG-containing breads.
- Extracted MNG improved loaf volume and specific volume of bread.
- Extracted MNG reduced moisture loss and hardness of bread crumb.

Malva nut gum (MNG) was extracted by alkaline solution. The previous studies showed that the extract had viscosity and gelling properties as well as inhibited α-amylase activity in starch solution 1.5-2.0 folds higher than that of original malva nut gum. This research was aimed to investigate the α-amylase inhibitory effect of alkaline-extracted MNG in solid food and to determine physical properties of MNG-containing bread. The scanning electron microscopy of in vitro digestibility with α-amylase of MNG-containing breads showed less porosity and more undigested starch granules remained intact with the matrix compared to control. This finding was consistent with the reduction of glucose (33-40%) and maltose (23-39%) levels compared to that of control after α-amylase digestion for 180 min in a dialysis system. The results showed that extracted MNG significantly (p < 0.05) increased loaf volume, and moisture content by 1.5-12%, and 8.2-12.8%, respectively compared to that of control. Addition of extracted MNG in bread formulation significantly reduced moisture loss and firmness of the bread crumb after storage for three days.