title: Pepsin diffusion in dairy gels depends on casein concentration and microstructure.
abstract: Fundamental knowledge of gastric digestion had only focused on acid diffusion from the gastric fluid, but no data are available for pepsin diffusion. Using fluorescence recovery after photobleaching technique, diffusion coefficients D of fluorescein isothiocyanate (FITC)-pepsin were measured in rennet gels across a range of casein concentrations allowing to form networks of protein aggregates with different structures. To investigate the microstructural parameters of native gels, electron microscopy image analysis were performed and qualitatively related to diffusion behavior of FITC-pepsin in these dairy gels. This study is the first report on quantification of pepsin diffusion in dairy product. Pepsin diffusion in rennet gels depends on casein concentration and microstructure. Models of polymer science can be used to assess D in dairy gel. Such data should be confronted with pepsin activity in acidic environment, and will be very useful as input parameters in mathematical models of food degradation in the human stomach.
authors.affiliation: STLO, UMR 1253, INRA, Agrocampus Ouest, Rennes, France. Electronic address: jonathan.thevenot@inra.fr.
authors.forename: J
authors.initials: J
authors.lastname: Thévenot
authors.affiliation: STLO, UMR 1253, INRA, Agrocampus Ouest, Rennes, France. Electronic address: chantal.cauty@inra.fr.
authors.forename: C
authors.initials: C
authors.lastname: Cauty
authors.affiliation: BIA-BIBS, INRA, Nantes, France. Electronic address: david.legland@inra.fr.
authors.forename: D
authors.initials: D
authors.lastname: Legland
authors.affiliation: STLO, UMR 1253, INRA, Agrocampus Ouest, Rennes, France. Electronic address: didier.dupont@inra.fr.
authors.forename: D
authors.initials: D
authors.lastname: Dupont
authors.affiliation: STLO, UMR 1253, INRA, Agrocampus Ouest, Rennes, France. Electronic address: juliane.floury@agrocampus-ouest.fr.
authors.forename: J
authors.initials: J
authors.lastname: Floury
mesh_terms: D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism*; D002417:Cattle; D012085:Chymosin / Q000737:chemistry / Q000378:metabolism; D004058:Diffusion; D004063:Digestion / Q000502:physiology; D005782:Gels; D006801:Humans; D005779:Immunodiffusion / Q000379:methods; D008892:Milk / Q000737:chemistry* / Q000378:metabolism*; D010316:Particle Size; D010434:Pepsin A / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002364:Caseins; D005782:Gels; C025350:rennet; D010434:Pepsin A; D012085:Chymosin
keywords: Diffusion coefficient; Electron microscopy; FRAP; Image analysis; Microstructure; Pepsin; Rennet gel