Interactions between beta-lactoglobulin and pectins during in vitro gastric hydrolysis.
This paper deals with the influence of different levels of three pectins, low-methylated pectin (LMP), high-methylated pectin (HMP), and low-methylated and amidated pectin (LMA), on the in vitro gastric hydrolysis of beta-lactoglobulin (beta-lg). Proteolysis by pepsin consisted of a 2-h progressive reduction of pH. A turbidity measurement of beta-lg-pectin mixtures was carried out during the proteolysis. The influence of pectins on pepsin enzymatic activity was also evaluated. beta-Lg was resistant to peptic digestion. The presence of each of the three pectins at a concentration of 50 wt % increased the N release at all pH values considered, despite a significant inhibition of the pepsin enzymatic activity with the pectins. The turbidity of beta-lg solutions during proteolysis was reduced by the addition of pectins, because of the formation of electrostatic complexes between this protein and pectins. The increase of N release could be a false positive result due to the difficulty of precipitating protein by trichloroacetic acid because of the formation of electrostatic complexes demonstrated by the decrease of turbidity.
Nacer
Ahmed
A
Laboratoire des Sciences Animales, ENSAIA-INPL, 2 Avenue de la Forêt de Haye, 54500 Vandoeuvre-lès-Nancy Cedex, France.
Sanchez
Christian
C
Villaume
Christian
C
Mejean
Luc
L
Mouecoucou
Justine
J
D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007782:Lactoglobulins / Q000737:chemistry / Q000378:metabolism*; D008745:Methylation; D009391:Nephelometry and Turbidimetry; D010368:Pectins / Q000737:chemistry / Q000494:pharmacology*; D010434:Pepsin A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055672:Static Electricity
D007782:Lactoglobulins; D010368:Pectins; D010434:Pepsin A