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

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 0mM to 7.5mM), 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 10mM, 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.