Value-added utilization of hemoglobin and its hydrolysis products from livestock and poultry blood processing by-products: A review

Background: Hemoglobin, a by-product of livestock and poultry blood processing, is an excellent source of bioactive compounds and high-quality proteins. The utilization of such by-products as raw materials in food processing can minimize environmental impact and add value to blood product wastage. Additionally, using hemoglobin from livestock blood can potentialize existing food protein resources, thus providing consumers with a wider range of choices. Scope and approach: This review examines decolorization and flavor enhancement processes of hemoglobin and its hydrolysates, as well as their biological activities and applications in foods. Innovative technologies can increase the value of hemoglobin utilization and expand its potential use in the food and pharmaceutical industries. Key findings and conclusions: Although the hydrolysis or degradation of hemoglobin reduces the formation of deep red color and metallic taste in the corresponding hydrolysates, bitterness in the hydrolysates limits their practical application. Enzymatic reactions, such as gamma-glutamylation, plastein reaction, and exonuclease treatment, can effectively address these issues. Future research should focus on the bioactivity of hemoglobin and its hydrolysates in living organisms and the characteristics of food processing. This will aid in creating a circular bioeconomic model with positive economic, environmental, and social impacts, represented by the high-value utilization of hemoglobin.