Enhanced Enzymatic Degradability of Livestock Blood Pretreated with Ultrasonic Technique

Livestock blood, a major organic waste generated by the livestock industry, poses a risk of pollution due to its rapid decomposition. However, it is a potential protein source for agricultural purposes due to its protein-rich organic matter. In this study, we conducted studies on an eco-friendly, scalable, and effective protein degradation process using livestock blood to reduce waste and produce an amino acid liquid fertilizer that can be recycled for agricultural use. Ultrasonic technology was applied as a pretreatment method to improve the enzymatic hydrolysis efficiency of proteins in livestock blood, and the optimal conditions that led to 95.91% solubilization rate of hemoglobin were ultrasound duration for 30 min at an ultrasound density of 0.5 W/mL. As a result of hydrolyzing ultrasonically pretreated blood by mixing exo- and endo-type proteolytic enzymes, the optimal combination was a mixture of Savinase® 1% and Flavourzyme® 1%. After 4 h of reaction, the protein concentration was 27.8 mg/mL and the amino acid concentration was confirmed to be 54.6 mg/mL. This is about 4.2 times higher than the amino acid concentration of blood without ultrasound pretreatment, 13.1 mg/mL, and it was confirmed that sonication has a significant effect on improving protein degradation efficiency. As protein degradation increased, the viscosity of blood gradually decreased, suggesting that the physical force applied to the agitator torque diminished during the enzyme reaction; a significant correlation between protein and amino acid concentrations (biological factors) and torque (mechanical factor) was observed. Measuring torque during an enzyme reaction can confirm the extent of the enzyme reaction, so it can be used as an indicator of reaction progress when scaling up the process in the future.