Substitution of wheat flour with wholegrain flours affects physical properties, sensory acceptance, and starch digestion of Chinese steam bread (Mantou)

- Wholegrain substitution destroyed the physical characteristics of Mantou.
- Wholegrain substitution reduced hydrolysis index of Mantou.
- Mantou made of high oat level exerted a lower HI and remained sensory acceptability.

This study investigated the effects of partial replacement of wheat flours with wholegrain flours on the physical characteristics and starch digestion of Mantou. Mantou was made with wheat flours partially substituted with brown rice or oat flours at the levels of 10% or 30%. Physical characteristics, including adhesiveness, hardness and springiness, of Mantou were significantly affected with substitution due to the disruption of dough structure. SEM observation evidenced that wholegrain incorporation resulted in discontinuous and irregular structure of Mantou. Sensory evaluation found that lower wholegrain incorporation of Mantou with lighter color exhibited higher score. Correlation analysis between physical parameters and sensory evaluation showed that appearance attraction negatively correlated to b* (yellowness-blueness) value. Compared with Mantou without substitution, wholegrain postponed starch digestion. Oat exerted particularly stronger effect because hydrolysis index (HI) decreased from 121 to 74 and 67 as the incorporation brown rice and oat at the level of 30%, respectively. In conclusion, our results revealed that wholegrain levels affected physical characteristics, sensory acceptance and nutritional quality of Mantou. Although the acceptance score of Mantou incorporated with oat flour was around 5 (neither dislike nor like), oat incorporation with a lower HI may provide an alternative choice for health concern.