Abstract: In order to develop egg products suitable for various cooking procedures by using egg and soybean as the main raw materials, the formulations of soft and firm egg tofu were optimized by comparing texture properties with others of the same type. The results showed that the optimal formulation of soft egg tofu was as follows: volume ratio of liquid whole egg to soy milk (with protein content of 6.5%) 2:9, pyrophosphate concentration 0.7%, agar concentration 0.02%, and δ-glucolactone concentration 0.3%. The hardness of this formulation was 392.75 g/cm2 and the chewiness was 17.75 mJ. The optimal formulation of hard egg tofu was as follows: volume ratio of liquid whole egg to soy milk (with protein content of 10.0%) 4:7, pyrophosphate concentration 1.0%, and agar concentration 0.02%. The hardness of this formulation was 1 002.17 g/cm2 and the chewiness was 53.52 mJ. When the volume ratio of liquid whole egg to soy milk was 2:9 or 5:6 for protein contents of soy milk of 7.5% and 9.5%, respectively, there was a deviation from the positive correlation between tofu hardness and the amount of liquid whole egg added. This deviation was verified by scanning electron microscopy and microscopic analysis based on differential thermal analysis (DTA), but the underlying mechanism needs further study.

Key words: egg tofu; formulation; texture properties; scanning electron microscopy; differential thermal analysis