“Effect of NaCl adittion and high pressure treatment on thermal properties of soybean proteins”

SPERONI, F,; BOLONTRADE, A.J; AÑON, M.C; DE LAMBALLERIE, M

Valencia, España

Congreso; Food INNova 2010; 2010

High pressure (HP) is an emerging technology in food handling that modifies protein structure and their functional properties. Composition of the dispersion medium of proteins may affect the effects of HP. The aim of this work was to analyze the combination of NaCl and HP treatment on thermal properties of soybean proteins. Soybean protein isolate, a b-conglycinin-enriched fraction (7SEF) and a glycinin-enriched fraction (11SEF) were treated at 200; 400 or 600 MPa in absence or presence of NaCl (0.1; 0.2; 0.4 and 0.6 mol/L). The denaturation temperature (Td) increased for both globulins when NaCl concentration increased being glycinin more sensitive than b-conglycinin. The magnitude of the Td increase was similar in 7SEF and 11SEF suggesting that this effect was independent of b-conglycinin and glycinin proportion. Denaturation enthalpy was also increased as NaCl concentration augmented. HP provoked denaturation of b-conglycinin and glycinin. After HP treatment both globulins maintained their Tds, with the exception of glycinin at 0.2 mol/L suggesting that HP did not modify thermal stability of NaCl-added soybean proteins. The degree of denaturation in presence of NaCl was smaller than in its absence and decreased as NaCl concentration increased, revealing a protective effect of both proteins towards HP. This protective effect was detected at 200 and 400 MPa for both proteins and for glycinin at 600 MPa also. The magnitude of this baroprotective effect was greater in glycinin than in b-conglycinin. The decrease in HP-induced denaturation degree exerted by NaCl probably affects the functional properties of HP treated soybean proteins