Effect of limited hydrolysis of soy protein on the interactions with polysaccharides at the air-water interface

MARTINEZ, KARINA D.; CARRERA SANCHEZ, CECILIO; PIZONES RUIZ-HENESTROSA, VICTOR; RODRÍGUEZ PATINO, JUAN M.; PILOSOF ,ANA M.R.

Montreaux, Suiza

Congreso; Food Colloids 2006; 2006

The Nestlé Research Center Lansanne The Univ. of Fribourg

Enzymatic treatment with proteases can substantially enhance foaming and emulsifying properties of proteins. Polysaccharides are commonly added to increase the stability of dispersed systems. There is some evidence that supports interactions between proteins and polysaccharides at fluid interfaces which has been related to enhance functionality of adsorbed  proteins. The objetive of present work was to study the effect of  soy protein hydrolysis on its  interaction with active and non-surface active polysaccharides at fluid interfaces by dynamic methods. A commercial sample of soy protein (SP) was used as starting material and protein hydrolisates of 2 (HSP1) and 5.35 % (HSP2) degree of hydrolisis (DH) were obtained. The following polysaccharides were added at 0.25% wt to solutions containing 2% wt : an  hydroxypropylmethylcellulose  (E4M) as surface active polysaccharide ; lambda carrageenan and locust bean gum. The surface pressure (p) and viscoelasticity as a function of time were evaluated with a drop tensiometer at 20ºC In the presence of E4M  as DH  of protein increased  differences in p and viscoelasticity. When SP and HSP1 were used the surface pressure achived intermediate value in between p values por single components indicating a competitive behavieur at the interface. . However, when HSP2 was used, existed an anthagonic behaviour, as surface pressure was lower than single components . Film viscoelasticity for the mixtures SP-E4M was dominated by E4M and for the mixtures HSP2 by the protein; and intermediate behaviour was apparent for HSP1-E4M film  A synergystic effect on p was observed for SP-lam carrageenan  and HSP1-lam carrageenan. However with HSP2 the interaction was anthagonic.Film viscoelasticity for the mixtures SP-lam carrageenan  and HSP1-lamcarra was governed by the polysaccharide, for HSP2 was dominated by the hydrolisate. Locust bean gum had  very little influence on the surface pressure of mixed system,it was noted a synergistic effect between SP and LB in film viscoelasticity; and anthagonic interaction fo HSP1-LB and intermediate behaviour for HSP2-LB film. These results, show that highter is the hydrolisis degree, the protein plays a more important role at the interface. It can be concluded tha polysaccharides strongly influence the interfacial behavior of soy proteins.