Kinetics of in Vitro Bread Bolus Digestion with Varying Oral and Gastric Digestion Parameters

The rate of bolus disintegration in the stomach plays an important role in gastric emptying, which has been shown to be directly correlated with post-food consumption blood glucose levels and satiety. This study examined the effect of various oral and gastric factors on bread bolus disintegration, including flour type, hydrodynamic forces, saliva level, and presence of alpha-amylase. The kinetics of bolus disintegration were determined by measuring the mass retention of boluses and fitting their disintegration profiles to a linear-exponential model. Artificially masticated bread was mixed with simulated saliva to form a bolus, which was soaked in simulated gastric juice for 120 min. The mass retention kinetics during static and agitated soaking followed three distinct profiles: exponential, sigmoidal, and delayed sigmoidal. The differences in profiles were attributed to varying levels of water absorption, caused by variations in bread structure and moisture content. Increasing the bolus saliva level decreased cohesive forces and increased bolus disintegration rate. These changes could have been caused by the increase of water inside the food matrix, or by the softening effect of alpha-amylase, which was shown to have a significant effect on bolus texture and also caused an increase in bolus disintegration. This work studies the driving factors in the breakdown of different types of bread during simulated gastric digestion. Our results demonstrate that bread structure and moisture content are key features controlling the rate of bread breakdown during gastric digestion.