Properties of Hemoglobin Decolorized with a Histidine‐Specific Protease

This study investigated the application of Aspergilloglutamic peptidase (AGP) on porcine hemoglobin decolorization. AGP from fungus Aspergillus niger is identified to possess a high preference towards the histidine residues. As histidine residues in hemoglobin are known to coordinate the heme group within the globin molecule, we therefore hypothesized that incubating hemoglobin with a histidine‐specific protease would efficiently separate the non‐heme peptides from the heme‐enriched peptides with a minimum degree of hydrolysis. AGP‐decolored porcine hemoglobin hydrolysates were assessed on their functional (for example, color, emulsification, foaming, and water binding) and sensory properties. The results were compared with commercially available blood‐derived proteins (subtilisin‐decolored hemoglobin hydrolysates and plasma protein). It was observed that AGP is able to effectively decolor hemoglobin. The degree of hydrolysis (DH) increased less than 3% using AGP to achieve 90% color reduction of hemoglobin, whereas a DH increase of more than 20% is needed using subtilisin. The AGP‐decolored hemoglobin hydrolysates (AGP‐Hb) possess good emulsification, foaming, and water binding properties, which are better or comparable with the plasma protein, and much better than the subtilisin‐decolored hemoglobin hydrolysates (subtilisin‐Hb). The model canned meat with addition of AGP‐Hb showed the highest value in hardness, springiness, and chewiness from the texture analysis. Furthermore, the canned meat with AGP‐Hb was found to have a better sensory profile than the ones with addition of subtilisin‐Hb and plasma protein.