Physicochemical and Consumer Acceptance of Tofu Supplemented with Licorice Powder

To develop functionally and nutritionally improved tofu, the effects of partial (0.2~0.8%) replacement with licorice powder (LP) on the quality characteristics of tofu were investigated. The pH and turbidity values decreased upon addition of increasing amounts of LP (P<0.05). The yield of LP-supplemented tofu was higher than that of the control tofu, and it increased as the concentration of LP increased (P<0.05). Substituting 0.6% and above of LP significantly hardened the texture of tofu (P<0.05) while control and 0.2~0.4% samples were not significantly different among them (P> 0.05). Lightness significantly decreased with higher LP content in the formulation (P<0.05), as indicated by visual observation that the color of tofu became darker. Redness and yellowness significantly increased (P<0.05). 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid radical scavenging activities significantly increased (P<0.05) with higher substitution of LP, and they were well correlated. Tofu incorporated with LP (0.2~0.8%) had a better shelf life which was approximately 4.32~26.64 h longer than the control tofu at the elevated temperature of 15°C. Finally, consumer acceptance test revealed that supplementation of LP more than 0.4% had an adverse effect on general consumer acceptance. On the basis of the overall observations, tofu samples supplemented with 0.2% (w/w) LP were found to benefit from the functional properties of LP, without compromising consumer acceptance.