Study of combined effect of soy protein hydrolysate and polysaccharides on foaming and rheologic properties on continuous phase

MARTÍNEZ, K. D.; PILOSOF, A.M.R

Centro de Eventos y Convenciones Dinosaurio Mall, Córdoba – Argentina

Congreso; III Congreso Internacional de Ciencia y Tecnología de los Alimentos Córdoba 2009 (CICyTAC 2009); 2009

Dra. Victoria Rosati. Directora de Vinculación Tecnológica, MINCYT Cba

The concentration effect of three biopolymers on foaming and continuous phase properties at heating and cooling conditions were evaluated by Response Surface Methodology. A soy protein hydrolysate (called H3 due to  the degree obtained) with 4% degree of  hydrolysis by enzymatic method and two polysaccharides (an hydroxypropylmethylcellulose called E4M and k-carrageenan (kC)) were selected to improve the hydrolysate foaming stability and compensate theirs functional properties by gelling or melting character of these polysaccharides, performing as egg white proteins-like functionality. The concentrations used were 2 to10% (wt/wt) for H3; 0,2 to 1,8% (wt/wt) for E4M and 0,2 to 1,8% (wt/wt) for kC. Therefore, the complete design involved a total of 15 experimental data points (EP) with a replica of central point (1, 14 and 15 EP). The pH  was 7.0, in distilled water (without salts). The foams were produced by whipping method, overun was measured and stability was studied through liquid drainage and collapse of the foams as a function of time (height of foams). The obtained results showed that the combined addition of E4M and kC is an adequate strategy to generate hydrolysates of soy proteins with good foam stability at heating and cooling conditions. The huge stability increase of foams at heating conditions was ascribed to combined effect between gelling property of E4M and the viscozieng character imparted by kC to continuous phase of foams. The combined effect of components on elastic module (G¨) and the relative viscoelasticity of foams (tan d), showed that E4M is the determining component at 70°C. However, a high H3 or kC concentration, prevents the E4M gel formation, giving a reduced G´ value and relative viscoelasticity. To obtain a high liquid drainage stability at cooling conditions (from 70°C to 10°C), the melting temperature of E4M should be close to the gelling temperature of kC, to maintain a gelling structure during the cooling process. To achieve a high stability against collapse of foams (bubbles rupture and decrease of the height) during the cooling storage is required a high elastic module of the continuous phase imparted by the gelling character of kC.