Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs.
The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (beta-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that beta-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and beta-lg, which reduced beta-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the beta-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the beta-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da.
Mouécoucou
J
J
Laboratoire des Sciences Animales, ENSAIA-INPL, USC INRA 2, Avenue de la Forêt de Haye BP 172, F-54505 Vandoeuvre-lès-Nancy Cedex 5, France. justinemouecoucou@yahoo.fr
Villaume
C
C
Sanchez
C
C
Méjean
L
L
D002918:Chymotrypsin; D003956:Dialysis; D004063:Digestion; D004591:Electrophoresis, Polyacrylamide Gel; D005503:Food Additives / Q000737:chemistry / Q000494:pharmacology*; D006170:Gum Arabic / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D066298:In Vitro Techniques; D007782:Lactoglobulins / Q000737:chemistry / Q000378:metabolism*; D009391:Nephelometry and Turbidimetry; D009584:Nitrogen / Q000737:chemistry; D010368:Pectins / Q000494:pharmacology; D010434:Pepsin A; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology*; D014357:Trypsin; D014990:Xylans / Q000494:pharmacology
D005503:Food Additives; D007782:Lactoglobulins; D011134:Polysaccharides; D014990:Xylans; D010368:Pectins; D006170:Gum Arabic; D002918:Chymotrypsin; D014357:Trypsin; D010434:Pepsin A; D009584:Nitrogen