Properties of Hemoglobin Decolorized with a Histidine-Specific Protease

Area of Science:

• Biochemistry
• Food Science
• Enzymology

Background:

• Hemoglobin decolorization is crucial for food applications.
• Existing methods using proteases like subtilisin cause significant protein hydrolysis, affecting functional properties.
• Histidine residues in hemoglobin are key to heme coordination, suggesting targeted enzymatic cleavage is possible.

Purpose of the Study:

• To investigate the efficacy of Aspergilloglutamic peptidase (AGP) for porcine hemoglobin decolorization.
• To evaluate the functional and sensory properties of AGP-decolored hemoglobin hydrolysates.
• To compare AGP-treated hemoglobin with conventionally treated hemoglobin and plasma protein.

Main Methods:

• Incubation of porcine hemoglobin with histidine-specific AGP from Aspergillus niger.
• Assessment of functional properties: color, emulsification, foaming, and water binding.
• Sensory evaluation and texture analysis of model canned meat products.

Main Results:

• AGP achieved 90% hemoglobin color reduction with <3% degree of hydrolysis (DH), compared to >20% DH for subtilisin.
• AGP-decolored hemoglobin hydrolysates (AGP-Hb) showed comparable or superior emulsification, foaming, and water binding to plasma protein.
• AGP-Hb significantly improved texture (hardness, springiness, chewiness) and sensory profile in canned meat.

Conclusions:

• AGP is a highly effective enzyme for decolorizing hemoglobin with minimal hydrolysis.
• AGP-decolored hemoglobin hydrolysates offer enhanced functional and sensory attributes for food ingredient applications.
• This enzymatic approach presents a promising alternative to conventional protein modification techniques.