Abstract

In this study, experimental in vitro models simulating the environment of the human gastrointestinal tract were used to assess the impact of physiological surfactants, such as bile salts, on the kinetics of digestion. Bile salts are biosurfactants synthesised in the liver and secreted together with bile into the small intestine. There are many reports on the role of bile salts in lipolysis, but the knowledge of their influence on other nutrients, such as proteins, is very limited. The experiments I conducted included the comparison of a model system (individual bile salts) with real human bile (containing different concentrations of bile salts, phospholipids, and other substances) during in vitro lipolysis and proteolysis. Human bile samples were obtained in cooperation with a clinical hospital. For the first time, a quantitative analysis of the effects of human bile on the digestion of a model food protein and lipid was performed. Moreover, for the first time, the currently used static in vitro digestion models were validated from the point of view of the physiological role of bile salts in the human digestive tract. In this respect, it has been demonstrated in vitro how the effect of human bile on the proteolysis and lipolysis can be reliably reproduced by applying mixtures of individual bile salt and phospholipids.

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