Enhanced CaSO4-induced gelation properties of soy protein isolate emulsion by pre-aggregation

•Rheological properties of SPI emulsion gels were markedly improved by pre-aggregation.•SPI emulsion gels processed by pre-aggregation had better water-holding capacity.•Sufficient pre-aggregation promoted emulsion to form stronger gel with uniform network.•Over pre-aggregation made the gel structure coarse.

The effects of CaSO4-induced pre-aggregation on the rheological and structural properties of soy protein isolate (SPI) emulsion gels were investigated. As the Ca2+ concentration during pre-aggregation increased (from 0 mM to 7.5 mM), the elastic modulus of the gels showed substantial increase, indicating stiffer gel structures. Large-deformation rheology suggested stronger but more brittle networks formed at higher Ca2+ concentration during pre-aggregation. However, when the pre-aggregated Ca2+ concentration reached 10 mM, the corresponding gel became weaker. Water-holding capacity (WHC) of the gels were significantly improved via the pre-aggregation process. The differences in rheological properties and WHC among the gels were consistent with the variation in their microstructures. Pre-aggregation helped to form denser and more uniform structures with thicker strands, whereas over aggregation made the gel network coarser.