6533b7d4fe1ef96bd1262916

RESEARCH PRODUCT

Chewing bread: impact on alpha-amylase secretion and oral digestion

subject

description

During chewing, saliva helps in preparing food bolus by agglomerating formed particles and initiates food enzymatic breakdown. However, limited information is actually available on the adaptation of saliva composition during oral processing of complex foods, especially for foods that are sensitive to salivary enzymes. We addressed this question in the context of starch–based products and salivary alpha-amylase. The objectives were two-fold: 1) determining if salivary alpha-amylase secretion can be modulated by bread type and 2) evaluating the contribution of the oral phase in bread enzymatic breakdown.Mouthfuls of three different wheat breads (industrial, artisan and whole breads) were chewed by twelve subjects. Saliva samples were collected at rest and at different times corresponding to 33, 66 and 100% of individual chewing sequence. Alpha-amylase activity and total protein content were determined for all saliva samples collected. Moreover, salivary maltose concentration was measured as a marker of bread enzymatic digestion. Boluses were collected at swallowing time (100% of chewing sequence) in order to evaluate saliva uptake.Chewing industrial bread induced higher saliva uptake than the other breads, despite a similar chewing duration. Evolution of salivary amylase activity tended to depend on the type of bread and was highly influenced by inter- and intra- subject variability. Proteins and maltose concentration steadily increased during chewing, as a result of bread breakdown. Salivary protein concentration was mainly affected by the release of breads water-soluble proteins. Salivary maltose concentration was found to be significantly lower for the whole bread. When considering the weight of mouthful, enzymatic breakdown was found to be the most efficient in industrial > artisan > whole breads.These results suggest that 1) variation of bread properties have limited impact on amylase secretion indicating that salivary adapting process does not occur in this case and 2) differences in enzymatic breakdown between breads are already observed during the oral phase of digestion.