Abstract：The activity and solubility of trypsin were found to be increased by 104.9% and 2.4% after ultrasonic treatment, respectively. Based on this result, we proposed an ultrasound-assisted enzymatic hydrolysis process for preparing antioxidant peptides from porcine blood. The optimal hydrolysis parameters that produced the same degree of hydrolysis as that obtained after 6 h hydrolysis by the routine procedure were determined by using single-factor and orthogonal array designs based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity as follows: ultrasonic frequency, 20 kHz; ultrasonic time, 8 min; ultrasonic power, 540 W; addition of trypsin, 0.8%; and initial pH, 8.0. The resulting hydrolysate could scavenge 75.78% of DPPH radicals. To conclude, this study demonstrates that ultrasound treatment can increase the hydrolysis efficiency of porcine blood and shorten the hydrolysis time.
