Development of an in vitro dynamic digestion system to study food digestion

The best model for studying food digestion remains the Human himself. However, getting ethical agreement to perform such experiments on human is difficult. Developing in vitro digestion tools appears as a crucial step for monitoring the behaviour and the kinetics of hydrolysis of the food during the different phases of the digestion process. The objective of this work was to develop a simple and rather cheap dynamic digestion system enabling the study of the disintegration occurring in in the gastro-intestinal tract. The device consists in two compartments i.e. stomach and small intestine and is controlled by the STORM (STOmach Regulation and Monitoring) software. This digestion system simulates the GI physiological states as follows: i) flow of secretions and enzymes in physiological amounts (pepsin, lipase, bile, pancreatin), ii) appropriate pH (acidification curve in the stomach) and neutralization of the pH in the intestine, iii) mixing in each compartments, iv) physiological transit time for the gastric and intestinal step of digestion. The differents functions are monitored by the sofware and are saved all along the digestion process. Relevant physiological parameters are essential to simulate as close as possible the human GI tract. To achieve this aim, an exhaustive analysis of the data from the literature has been realized in order to adjust the parameters of the digestion model, and the key parameters such as gastric acidification curve, gastro-intestinal emptying rate and enzymes flow have been modelled as a function of the stage of life (infants vs adults). Validation of this model by a comparison of the kinetics of proteolysis of an infant formula observed either in an animal model (piglets) or in the in vitro model is currently under investigation. This model offers numerous advantages as compared to in vitro static models. Despite this, the model should be improved by (1) making the stirring conditions more physiologically relevant, (2) adding a dialysis membrane to mimic nutrients absorption in the intestinal compartment.