EFFECTS OF NACL ADDITION AND HIGH PRESSURE TREATMENT ON THERMAL PROPERTIES OF SOYBEAN PROTEINS

FRANCISCO SPERONI; AGUSTÍN BOLONTRADE; MARÍA CRISTINA AÑÓN; MARIE DE LAMBALLERIE

Valencia

Congreso; International Conference on Food Innovation; 2010

Universidad Politécnica de Valencia

High pressure (HP) is an emerging technology in food handling that modifies protein structure and their functional properties. Composition of dispersion medium of proteins may affect the effects of HP. The aim of this work was to analyze the combination of NaCl and HP on thermal properties of soybean proteins. Soybean protein isolate, a β-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 β-conglycinin. The magnitude of Td increase was similar in 7SEF and 11SEF suggesting that this effect was independent of β-conglycinin and glycinin proportion. Denaturation enthalpy was also increased as NaCl concentration augmented. HP provoked denaturation of -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 with NaCl concentration, revealing a protective effect in both proteins towards HP. This protective effect was detected at 200 and 400 MPa for both proteins, but only for glycinin at 600 MPa. The magnitude of baroprotection was greater in glycinin than in β-conglycinin. The decrease in HP-induced denaturation degree exerted by NaCl probably affects the functional properties of HP treated soybean proteins.