Relationship between breaking load and protein composition of acidic heat-induced gels prepared from the acidic precipitate of soy flour aqueous dispersions.

As one of the constituent materials of plant-based meat, a heat-induced gel was prepared from the aqueous paste (protein-to-water ratio: 0.30-0.35) of an acidic precipitate from soy flour called AP-SF. Among the broader pH range of 4.5-7.5, heat-induced gels prepared from the AP-SF paste adjusted to a pH range of 5.0-5.5 exhibited the similar breaking load (617 gf) and displacement (5.22 mm), to that of heat-induced gels prepared from minced beef, breaking load (667 gf) and displacement (6.45 mm). The results of two experiments, that is, the addition of fractionated protein components (7S, 11S, polar lipid-associated protein (PLAP), and oil body-associated protein (OBAP)) to the original AP-SF gels and the examination of a correlation between the breaking load of AP-SF gels and the protein composition of soybean cultivars used for the AP-SF preparation suggested that 7S globulin has an ability to effectively increased the breaking load of AP-SF gels. In globulins that contribute to gelation, the correlation between the content of 7S and 11S and the breaking load is 0.75 and 0.50, respectively, and the correlation coefficient of 7S is much higher than that of 11S. Analysis using dithiothreitol (DTT)-free SDS-PAGE confirmed that homodimers of the α' and α subunits of 7S globulin play a dominant role in the heat-induced gelation via the formation of intermolecular disulfide bonds with themselves or other protein components.