Abstract:Given the high degree of protein denaturation during the high-temperature pressing process, heat-pressed peanut meals have a low protein utilization rate in the food industry. In this study, heat- and cold-pressed peanut meals were hydrolyzed using different commercial proteases (e.g., alcalase 2.4 L, neutrase, papain, protamex, and flavorzyme 500 mg). The protein recovery, degree of hydrolysis (DH), molecular weight (MW) distribution, and antioxidant activities of their hydrolysates were compared to verify whether enzymatic hydrolysis was suitable to utilize these proteins in heat-pressed peanut meals and to select the appropriate protease. The results showed that the protein recoveries of heat-pressed peanut meals after hydrolysis by different proteases were 60.61~67.86%, which were comparable to the values of cold-pressed peanut meals. The highest DH (44.92%) was observed in the heat-pressed peanut meal hydrolysate prepared by flavorzyme hydrolysis, and there were numerous small peptides with a MW of < 3 ku and free amino acids. In addition, the 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging activities of different heat-pressed peanut meal hydrolysates were higher than those in cold-pressed peanut meal hydrolysates. This may be because heat-pressed peanut meal hydrolysates contain a larger number of small peptides and free amino acids with electron-donating ability as well as Maillard reaction products generated during the heat-pressing process.
