Comparison of rheological, tribological, and microstructural properties of soymilk gels acidified with glucono-δ-lactone or culture.

The physical properties of soymilk gels acidified with glucono-δ-lactone (GDL) or cultures with varying exopolysaccharide (EPS) production capabilities (EXPRESS CN < YFL-903) were studied. The acidification time and final pH were controlled in all samples. Earlier gelation and higher gelation pH were induced using GDL. The rheological properties and size distribution of GDL gel were closer to those of the EXPRESS CN gel than YFL-903 gel. Better lubrication property in the mixed regime was found in culture acidified gels, with YFL-903 gel showing the best results. Firmness, adhesiveness and water holding capacity were higher in culture- induced gels than in the GDL gel. The microstructures of the gels were found to be similar, but the subtle stranded structure of the GDL gel seemed denser than the culture-induced gel. The results suggest that both acidification rate and EPS production should be considered when comparing GDL and culture-induced soymilk gels.