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). [ABSTRACT FROM AUTHOR]