Effect of different pH (a), enzyme amount (b), extraction temperature (c), and liquid-to-solid ratio (d) on extraction yield of crude TFP. (a) Enzyme amount, extraction temperature, liquid-to-solid ratio, and extraction time were constant at 6000 u/g, 50°C, 40 ml/g, and 30 min, respectively. (b) pH, extraction temperature, liquid-to-solid ratio, and extraction time were constant at 4.5, 50°C, 40 ml/g, and 30 min, respectively. (c) pH, enzyme amount, liquid-to-solid ratio, and extraction time were constant at 4.5, 6000 u/g, 40 ml/g, and 30 min, respectively. (d) pH, enzyme amount, extraction temperature, and extraction time were constant at 4.5, 6000 u/g, 50°C, and 30 min. Error bars represent standard deviation of the means (n = 3).