Impact of the release rate of magnesium ions in multiple emulsions (water-in-oil-in-water) containing BSA on the resulting physical properties and microstructure of soy protein gel

- The stability of W/O/W emulsion was improved with an increase in BSA concentration.
- The presence of BSA in double emulsions reduced the coagulation rate of soymilk.
- Microstructure of tofu gel became more homogeneous with higher BSA levels.
- Physical properties of tofu were affected by the BSA contents in W/O/W emulsion.

The objective of present study was to prepare multiple water-in-oil-in-water (W/O/W) emulsions that exhibit different release rates of magnesium ions; and assess their utility as coagulants in improving tofu quality. W/O/W emulsions containing bovine serum albumin (BSA) and magnesium chloride (MgCl2) were developed for controlled release applications. An increasing BSA concentration led to an increase in viscosity and droplet size of W/O/W double emulsions, as well as a decreased release rate of encapsulated Mg2+ from emulsions. The gelation process of soy protein was simulated by conducting dynamic viscoelastic measurements. The rate constant (k) and saturated storage modulus (G′sat) values of soy protein gel decreased as BSA concentration increased, suggesting that BSA could slow the release of magnesium ions from double emulsions. Confocal laser scanning microscopy (CLSM) results showed that increased concentration of BSA created a more homogeneous microstructure of soy protein gels with smaller pores within the gel network structure.