title: Digestion of starch in a dynamic small intestinal model.
abstract: OBJECTIVE
  The rate and extent of starch digestion have been linked with important health aspects, such as control of obesity and type-2 diabetes. In vitro techniques are often used to study digestion and simulated nutrient absorption; however, the effect of gut motility is often disregarded. The present work aims at studying fundamentals of starch digestion, e.g. the effect of viscosity on digestibility, taking into account both biochemical and engineering (gut motility) parameters.
  
  
  METHODS
  New small intestinal model (SIM) that realistically mimics gut motility (segmentation) was used to study digestibility and simulated oligosaccharide bio accessibility of (a) model starch solutions; (b) bread formulations. First, the model was compared with the rigorously mixed stirred tank reactor (STR). Then the effects of enzyme concentration/flow rate, starch concentration, and digesta viscosity (addition of guar gum) were evaluated.
  
  
  RESULTS
  Compared to the STR, the SIM showed presence of lag phase when no digestive processes could be detected. The effects of enzyme concentration and flow rate appeared to be marginal in the region of mass transfer limited reactions. Addition of guar gum reduced simulated glucose absorption by up to 45 % in model starch solutions and by 35 % in bread formulations, indicating the importance of chyme rheology on nutrient bioaccessibility.
  
  
  CONCLUSIONS
  Overall, the work highlights the significance of gut motility in digestive processes and offers a powerful tool in nutritional studies that, additionally to biochemical, considers engineering aspects of digestion. The potential to modulate food digestibility and nutrient bioaccessibility by altering food formulation is indicated.
authors.affiliation: Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada (CICATA), Legaria 694, Irrigación, 11500, Mexico, D.F., Mexico.
authors.forename: M R
authors.initials: MR
authors.lastname: Jaime-Fonseca
authors.affiliation: School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: O
authors.initials: O
authors.lastname: Gouseti
authors.affiliation: School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Fryer
authors.affiliation: Reacta Biotech Limited, Manchester, UK.
authors.forename: M S J
authors.initials: MS
authors.lastname: Wickham
authors.affiliation: School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. s.bakalis@bham.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Bakalis
mesh_terms: D001939:Bread / Q000032:analysis; D004063:Digestion; D005685:Galactans / Q000737:chemistry; D005766:Gastrointestinal Contents / Q000737:chemistry; D005769:Gastrointestinal Motility; D006801:Humans; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000378:metabolism / Q000502:physiology*; D008351:Mannans / Q000737:chemistry; D008954:Models, Biological; D009844:Oligosaccharides / Q000493:pharmacokinetics; D053149:Plant Gums / Q000737:chemistry; D013213:Starch / Q000378:metabolism / Q000493:pharmacokinetics*; D014783:Viscosity
chemical_list: D005685:Galactans; D008351:Mannans; D009844:Oligosaccharides; D053149:Plant Gums; D013213:Starch; C007894:guar gum
keywords: Dynamic in vitro models; Intestinal motility; Simulated glucose bioaccessibility; Starch digestion