REFERENCES IMPACT OF PECTIN ON THE GASTRIC DIGESTIBILITY OF SODIUM CASEINATE - PowerPoint Presentation

1. REFERENCESIMPACT OF PECTIN ON THE GASTRIC DIGESTIBILITY OF SODIUM CASEINATE Ferreira-Lazarte1, Anabel Mulet2, Neil Rigby2, A. Mackie2, M. Villamiel1 1Instituto de Investigación en Ciencias de la Alimentación CIAL (CSIC-UAM). C/Nicolás Cabrera 9, Universidad Autónoma de Madrid, 28049 Madrid, España.2Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UKPectin is an anionic polysaccharide used in food applications which, due to its physical and chemical properties, can modify the absorption of nutrients and their passage through the gastrointestinal tract [1]. In this regard, protection by these polysaccharides to protein digestion (casein), probably due to the presence of electrostatic binding of pectin to proteins have been reported [2,3]. Adsorption of pectin to casein can take place at pH 3.5-5.0 by electrostatic interaction between the carboxylate group of pectin and cationic residue of casein. In this sense, protection by pectin to protein digestion can be very important when considering the absorption of nutrients and allergens in the small intestine, such is the case of casein; hardly any investigation has been carried out on the interaction casein/pectin during protein digestion. INTRODUCTIONOBJECTIVEMATERIAL AND METHODSRESULTSACKNOWLEDGEMENTS[1] A. Maroziene and C. G. de Kruif (2000) Food Hydro. 14, pp. 391-394[2] Y. Luo, K. Pan and Q. Zhong (2015) Int. J. Pharm. 486, pp. 59-68[3] R. L. El Kossori, C. Sachez, E. S. El Boustani, N. Maucourt, Y. Sauvaire, L. K. Meejan and C. Villaume (2000) J. Sci. Food Agric. 80, pp. 359-364[4] Minekus et al. 2014, Food Funct 5, 1113-1124[5] A. I. Mulet-Cabero, N. M. Rigby, A. Brodkorb and A. R. Mackie (2017) Food Hydro. 67, pp. 63-73CONCLUSIONThe objective of this work was to study the effect of citrus pectin and derivatives on the gastric digestion of sodium caseinate in a semi-dynamic gastric model.Citrus pectinSodium caseinateScheme used was a semi-dynamic gastric model based on the static protocol from Infogest [4]. Simulated Salivary Fluid (SSF), Simulated Gastric Fluid (SGF). Enzyme activities are in units per mL of final digestion mixture at each corresponding digestion phase. SEMI-DYNAMIC GASTRIC MODEL [5] Sampling 0, 1 and 2 h for testing milk casein by SDS-PAGEGastric Digestion 37 ºC12% Bis-Tris-Gel (Novex, NuPage) 200 V, 350 mA, 35 min and RunBlue Precast gels (180 V, 400 mA, 60 min) Protein / Citrus Pectin1/0.081/0.341/0.851/3.4NaHCO3 1 M (reaction stop)A) GASTRIC PH EVOLUTION DURING DIGESTIONFigure 1. pH profile during the simulated gastric digestion of caseinate with citrus pectinPresence of pectin in samples affected the pH diminution during the gastric digestion probably due to the formation of caseinate-pectin complexes.High values of pectin produced the lowest initial pH in samples.1) EFFECT OF CITRUS PECTIN ON CASEINATE DIGESTION2) EFFECT OF ENZYMATIC MODIFIED CITRUS PECTIN ON PROTEIN DIGESTIONB) EFFECT ON PROTEIN DIGESTIONcaseinsBSApepsinα-Laβ-LgFigure 2. Electrophoretic profiles of protein fractions (caseins, β-Lg, α-La, BSA) of caseinate-pectin samples before (0 h) and after 1 h (left) and 2 h (right) of gastric digestion (Bis-Tris-Gel, Novex, NuPage). M: Marker, 1, 1’, 5, 5’ Caseinate; 2, 2’, 6, 6’ Caseinate-Pectin 1/0.08; 3, 3’, 7, 7’ Caseinate-Pectin 1/0.85; 4, 4’, 8, 8’ Caseinate-Pectin 1/3.4.Diffuse bands are observed in pectin-caseinate mixtures at 0 h (2, 2’) probably due to electrostatic interactions of proteins with pectin.A protective effect of pectin was observed mainly in caseinate:pectin (1:0.08) samples.Bands corresponding to peptides are observed specially after 1 h digestion with higher intensity for the samples with lower caseinate:pectin ratio (6, 6’).Higher amounts of pectin gave rise to lower pH values (4.8 and 4.4) nearer to the optimum pH of pepsin (1.5-4.5) that could favour the digestion.0.65 0.61 0.82 1.06 0.77 0.83 0.70 0.80 Enzymatic treatmentViscozyme®/Glucanex®200 G(15 U/mL, pH 4.5, 24h, 50 ºC0.68 1.03 0.76 0.68 0.84 0.93 0.80 0.85 Enzymatic treatment was used to test the effect of different molecular weight (Mw) of pectin on the protein digestion.pH decrease showed a lower rate for pectins after enzymatic treatment compared to the intact pectin (no enzyme).Protective effect was only observed for intact pectin after 1 h of gastric digestion.Similarly to pH, that affect electrostatic interactions of these compounds, Mw of pectins could also play an important role on the resistant to digestion of proteins due probably to steric hindrance of these high Mw compounds.Figure 3. Electrophoretic profile (left) and pH curve (right) of caseinate with intact pectin and enzymatic treated (Viscozyme and Gluconex) pectin samples after gastric digestion: M: Marker, 1, 5, 9 Caseinate 6.5%; 2, 6, 10 Caseinate-Pectin; 3, 7, 11 Caseinate-Viscozyme treated pectin; 4, 8, 12 Caseinate-Gluconex treated pectin. Protein:Pectin ratio, 1:0.34. M 1 2 3 4 5 6 7 8 9 10 11 12 M 0 h 1 h 2 hThe obtained results in the semi-dynamic gastric system point out the protection of pectin on the digestion of sodium caseinate, particularly evident at times shorter than two hours, and the effect of the molecular weight of pectin on protein hydrolysis.This work has been funded by MINECO of Spain: Project AGL2014-53445-R.