Development of an in vitro system simulating bucco-gastric digestion to assess the physical and chemical changes of food

The release of nutrients from solid food depends on the physical and chemical characteristics of substrates, and on dynamic physiological events including pH, gastric emptying and enzymatic secretion. Our laboratory has developed an in vitro digestive system mimicking mouth and stomach processes to determine physical and chemical changes of bread during digestion. To simulate oral-phase digestion, bread was minced and subjected to in vitro amylase digestion, releasing 219 +/- 11 g oligosaccharides/kg total carbohydrate. During the gastric phase, bread proteins, which are converted into insoluble aggregated proteins during breadmaking, were emptied in various states of peptic digestion: undigested aggregated proteins and degraded proteins of intermediate and low molecular weight. The mean particle size of ground bread decreased progressively to the end of the gastric digestion (from 292 to 109 mm). The in vitro digestive system proved to be a useful tool for understanding the dynamic digestion of various food components held within the structure of a food matrix.