Antioxidant capacity and consumer acceptability of herbal egg tofu

- Herbs and spices contributed to the higher antioxidant activity of egg tofu.
- Herbs and spices addition affect the consumer acceptability of egg tofu.
- Egg tofu containing Zingiber officinale is the most preferred by the consumer.

A mixture design was used to optimize the herbal egg tofu formulation containing Polygonum minus, Curcuma longa and Zingiber officinale. The effects of the herbs on the total phenolic content (TPC), ferric reducing antioxidant power (FRAP) assay and scavenging activity 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS), texture profile (hardness, springiness, cohesiveness, gumminess and chewiness) and consumer preference on sensory characteristics (appearance, color, aroma, taste, texture and overall acceptability) of the herbal egg tofu were investigated. An increase in C. longa content produced egg tofu with significantly higher (p < 0.05) TPC and antioxidant activity (FRAP, ABTS and DPPH assay), but a significantly lower score for overall acceptability. An increase in the P. minus content significantly (p < 0.05) increased the springiness of the egg tofu. The optimum formulation of the egg tofu was determined by overlapping the contour plot related to sensory characteristics (color, taste and overall acceptability) and springiness that formed the region with optimum value. The results showed that the optimum predicted response value for color, taste, overall acceptability and springiness were 4.9, 4.6, 4.8 and 0.96 mm, respectively, which were obtained from a combination of 0.7% P. minus, 0.5% C. longa and 0.8% Z. officinale.