Arginine improves the color stability of hemoglobin powder during freeze-drying and storage.

To increase the color stability of hemoglobin (Hb) powder, the technological conditions for arginine-hemoglobin (Arg-Hb) powder preparation were optimized by response surface methodology and the influence of arginine (Arg) on the color stability of Hb powder was evaluated. Results showed that: (a) Arg-Hb powder had better colors (less MetHb% and higher a* value) than Hb powder (p < 0.05); (b) using MetHb% as an indicator, the optimal conditions to prepare Arg stabilized Hb were Arg concentration of 10.5 mg/ml Hb extract, reaction pH of 10.75, and reaction temperature of 18°C; (c) pH and NaCl had a significant influence on the color stability of Hb (p < 0.05). At various NaCl concentrations and pH conditions, Arg-Hb solution showed better color than Hb (p < 0.05); (d) Arg-Hb powder had higher a* values and higher percentages of deoxyhemoglobin and oxyhemoglobin but lower MetHb% than Hb powder during storage (p < 0.05).