Thermal behavior of emulsions manufactured with soy protein ingredients

The conformation, denaturation and aggregation behavior of proteins are important factors which dictate their ingredient functions and applications in formulated food products. The effect of variation in pre-treatment temperature (70-90 degrees C x 30 s), pH (6.4-7.5) and calcium supplementation (450 and 850 mg/L) on heat coagulation time (HCT at 140 degrees C) of model emulsions (3.6% (w/v) protein) stabilized with soy protein isolate (SPI) and soy protein hydrolysate (SPH) ingredients was determined. Generally, HCT of emulsions was not significantly affected by alteration of constituent pre-heating temperatures. Model emulsions displayed higher HCTs with increasing pH and lower levels of intrinsic ash content. At both supplementation levels, calcium addition led to decreased HCTs. Supplementation with chloride salts caused a greater decrease in HCT compared to supplementation with citrate salts. Furthermore, soy protein hydrolysis was associated with lower emulsion thermal stability. Results demonstrate that modification of ingredient and manufacturing parameters may be a useful approach for enhancing thermal stability properties of soy protein stabilized emulsions. (C) 2008 Elsevier Ltd. All rights reserved.