Thermal aggregation of soy protein isolates

PETRUCCELLI, S; AÑÓN, M.C.

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 1995 vol. 43 p. 3035 - 3041

0021-8561

Thermal behavior of soy protein isolates under different conditions of temperature, time, pH, protein concentration, and presence of reducing agents was studied. Thermal treatments above 85 °C showed a decrease in concentration of the AB-11S subunit and of the two protein species of 20 and 29 kDa,and a gradual increase in the concentration of the A and B polypeptides of glycinin. None of the thermal treatments tested led to modifications of the relative proportions either of the high molecular weight aggregates (100-200 kDa) observed in the electrophoretic profiles or of the a' and a subunitsof /3-conglycinin. Increasing the pH to 9 or 10 and increasing the protein isolate concentration enhanced AB-11S aggregation during the thermal treatment. Either the presence of Na2S03 or the pH 9-10 favored the /3-/3-conglycinin/B-glycinin aggregation. This interaction requires an increase of SH groups. Initially the /3-/3-conglycinin/B-glycinin aggregates were stabilized byhydrophobic interactions and later by SS bonds.