Interaction of high pressure and sodium chloride on soy protein denaturation

DE LAMBALLERIE, MARIE; AÑÓN, MARÍA CRISTINA; SIMONIN, H; SPERONI, FRANCISCO

Budapest

Congreso; 49th conference of European High Pressure Research Group (EHPRG); 2011

EHPRG

Soy proteins are of major interest in food processing, because of their worthwhile gelling and texturing properties, their nutritional value and their world-wide availability. High pressure (HP) treatment is a non-thermal food preservation technique which development expands greatly at the moment. Then the aim of this work was to improve the knowledge of the effect of high pressure on soy protein denaturation according to NaCl concentration. Soy Protein Isolate (SPI), glycinin enriched fraction (11SEF) and -conglycinin enriched fraction (7SEF) were prepared from defatted soybean flour and freeze-dried as described in previous work [1]. High pressure treatment was conducted at 200, 400 and 600 MPa for 10 min at 20 °C, soy proteins were 10% dispersions in NaCl solutions ranging from 0.2 to 0.6 mol/L. Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC) were used to characterize the protein denaturation. DSC results evidence interaction of HP and NaCl on soy protein denaturation, according to HP level, NaCl concentration, and soy protein fraction. Globally whatever the concentration, NaCl alone increases the Td values of 11S and 7S in the three extracts SPI, 11SEF and 7SEF. Without NaCl, HP treatment induces a decrease of the Td of 7S, and an increase of the Td of 11S. HP treatment combined with NaCl addition induces variable effects according to protein fraction and NaCl concentration. In particular NaCl addition leads to a protection of 7S and 11S against pressure denaturation at 200 MPa and 400 MPa, but it is not verified for the 7S fraction at 600 MPa. SEC results allow to know the aggregation degree of protein fractions after HP treatment or NaCl addition. They show that NaCl decreases the cooperativity between soy protein fractions, and that after HP treatment protein structures exhibit higher cooperativity than native structure.