Texture Profile of Tofu as Affected by Instron Parameters and Sample Preparation, and Correlations of Instron Hardness and Springiness with Sensory Scores



ABSTRACT:  Our objective was to characterize the variations of tofu textural profiles as affected by physical parameters and to correlate the data with that of the sensory method. The textural profiles of 13 selected tofu types were characterized using various crosshead speeds and 2 degrees of penetration using an Instron universal textural machine. Hardness (firmness) and springiness (elasticity) were also analyzed by a descriptive sensory analysis. The results showed that the degree of plunger penetration had a significant impact on textural properties. Hardness values obtained by both levels of penetration correlated significantly (r= 0.94 to 0.95) with the sensory hardness. Springiness obtained by the 50% penetration method did not correlate significantly with the sensory data, whereas 75% penetration had a significant correlation (r= 0.98). Hardness values obtained using tofu specimens without skin correlated better with sensory data than that obtained with skin, which typically results from a pressing step in traditional tofu-making process. The findings were the first in the literature to show linear correlations between instrumental and sensory tofu textural characteristics, and provided a basis for the selection of physical parameters for determining tofu textural properties using an Instron machine.