. Materials and methods
SPI and LMW-SPI were kindly donated by Fuji Oil Co. (Osaka,
Japan). The protein content of the SPI and LMW-SPI was both
>90 wt%. LMW-SPI is partially hydrolysed by proteases with an
average molecular weight of approximately 60,000 Da. Corn oil
(Mazola, ACH Food Companies, Inc., UK) was purchased from a local
supermarket in the UK. All other chemicals used were of Analytical
grade. Ambient temperature was approximately 25 C throughout
all the experiments.
2.1. Sample preparation
2.1.1. Macrogel
SPI and LMW-SPI were mixed with deionized water and then
the appropriate amount of salt solution was added to adjust the
concentration of salts. The final concentration of SPI and LMW-SPI
in the macrogels was 15 wt% and 20 wt%, respectively. The salt
concentration in the final macrogels was set at 0 mM (no added
salts), 60 mM for NaCl and 30 mM for CaCl2 or MgCl2. The concentrations
of the salts were determined according to the gelation
method reported by Kohyama, Sano, and Doi (1995). The cationic
salts were chosen based upon their use in the creation of tofu gels,
which are proposed as comparable to the microparticulated SPI gels
presented.
The SPI and LMW-SPI mixtures were stored in a water bath at
40 C for 30 min to allow enough hydration of the protein powders.