Influence of charged and non-charged co-solutes on the heat-induced aggregation of soy and pea proteins at pH 7.0

Abstract

This study investigated the influence of calcium chloride (CaCl2; 0–10 mM) and glucose syrup (GS; 0–20 wt%) addition on the heat-induced aggregation (95 °C for 15 min) of commercially available soy (SPI) and pea (PPI) protein isolates (3.5 wt%) at pH 7.0.Concentrations of CaCl2 above 5 mM promoted aggregation of both SPI and PPI dispersions, as inferred from the decrease in protein solubility and the increase in particle size. Furthermore, heat treatment of the PPI dispersion in the presence of 8 mM CaCl2 led to the formation of protein aggregates (D[4,3] = 11 μm) with a rather narrow particle size distribution (PSD), which resulted in a relatively high viscosity (>40 mPa s at 10 s−1). On the other hand, addition of GS had no influence on the heat-induced aggregation of SPI and PPI dispersions, with the increase in viscosity with increasing GS concentration being mainly due to the increase in total solids.Heat treatment of the PPI dispersions in the presence of both CaCl2 and GS provided an increase in both aggregation yield and viscosity (up to >70 mPa s 10 s−1) when compared with the dispersion heated in the presence of 8 mM CaCl2, although this was dependent on the processing method used.The pea protein aggregates produced in this study may be used as sustainable and clean label thickening agents in a variety of liquid and semi-solid vegetarian and vegan foods, thus allowing replacement of the food additives which are typically added to these products.