The effects of protein concentration and locust bean gum (LBG) addition on the mechanical properties, microstructure and water holding capacity of acidified soy protein (SPI) gels were studied. The protein was employed in two different states: (i) native and (ii) heat denatured. A slow acidification rate was induced in both systems by applying glucono-δ-lactone (GDL). The results indicated that the gels of native SPI were weaker, less deformable and showed lower water holding capacity than the gels of heat-denatured SPI. The LBG addition led to an increase in the strength and water holding capacity of SPI gels, independent of the protein state (native or denatured). These results indicated that the properties of texture and water holding capacity of the SPI acid gels can be modulated by the process conditions or by the addition of other ingredients, such as polysaccharides.