Effects of Salts Presence on Thermal Properties of High Pressure Treated Soybean Proteins

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

Nantes

Simposio; 6th International CIGR Technical Symposium; 2011

CIGR

High Pressure (HP) is an alternative to thermal pasteurization, which also modifies protein structure. Since HP is a water based technology, medium composition may affect their effects. NaCl and CaCl2 are important additives due to their effects on human health and functional properties of proteins. The aim of this work is to evaluate the effects of the presence of NaCl and CaCl2 during HP on thermal properties of soybean proteins. Soybean proteins, glycinin and b-conglycinin were prepared as Soybean Protein Isolate, a glycinin enriched fraction and a -conglycinin enriched fraction. NaCl concentrations ranged between 0.2 and 0.6 mol/L. CaCl2 concentrations ranged between 0.0025 and 0.025 mol/L. HP treatments were carried out at 20 ± 5 °C at 200; 400 or 600 MPa. Differential Scanning Calorimetry was carried out at 1°/min in a microDSCIII. NaCl increased Td of both globulins at any assayed concentration. CaCl2 exerted a two-phases effect on Td of b-conglycinin (decreasing at low and increasing at high concentrations). CaCl2 increased Td of glycinin at any assayed concentration. After HP, in NaCl added samples, Td remained constant for b-conglycinin, while Td increased for glycinin. In the case of CaCl2 added samples, both globulins increased their Td after HP. NaCl and HP increased cooperativity of -conglycinin and glycinin. CaCl2 increased cooperativity of -conglycinin, while it produced the split of glyicinin peak, indicating a decrease in cooperativity. The effects of CaCl2 on Td and cooperativity were dependent on the proportion of glycinin and b-conglycinin present in the samples, while those of NaCl were independent of this proportion. NaCl and CaCl2 protected both globulins towards HP (decreasing the denaturation degree) at 200 and 400 MPa. At 600 MPa salts protected glycinin but sensitized (increasing the denaturation degree) b-conglycinin. The results indicate that NaCl and CaCl2 modified the effects of HP on soybean proteins, and that in the case of CaCl2, specific interactions between calcium and proteins modulates the magnitude of the changes.