Optimization of Enzymatic Hydrolysis of Bovine Bone Marrow Protein and Its Physicochemical and Antioxidant Properties

The enzymatic hydrolysis of bovine bone marrow protein (BBMP) was optimized and its physicochemical properties and antioxidant activities were studied, aimed to explore the material basis of its potential medicinal and health benefits and enhance the comprehensive utilization value of beef bone. The degree of hydrolysis (DH), protein content, and 1,1-diphenyl-2-trinitrophenylhydrazine free radical (DPPH·) scavenging rate were used as evaluation indexes, combined with the results of structural characterization, the suitable enzyme was screened. The response surface methodology was used to the optimization of enzymatic hydrolysis of bovine bone marrow protein as the hydrolysis time, enzyme concentration, pH, and temperature were independent variables. Then, the physicochemical properties and antioxidant activities of the obtained hydrolysates were investigated. The results showed that pepsin was selected as the optimal protease for the preparation of BBMP pepsin hydrolysate (BBMP-PH). The optimum enzymatic hydrolysis conditions were time 2 h, enzyme concentration 2%, pH3, and temperature of 37 ℃. Under these conditions, the DH, protein content, and DPPH· scavenging rate were 36.07%, 37.05%, and 39.57%, respectively. The effects of four factors on the efficiency of enzymatic hydrolysis were ordered as: Enzyme concentration>enzymatic hydrolysis time>enzymatic hydrolysis temperature>pH. The results of physicochemical properties showed that the isoelectric point (pI) of BBMP-PH was about pH6, and the solubility, emulsifying activity, emulsion stability, and water holding capacity of BBMP-PH were up to their lowest value at pI, and the better when far from the pI. When pH was 2, BBMP-PH has the highest solubility (94.72%), whereas pH8 for the emulsifying activity and emulsion stability (1.11 m²/g and 101.37%). BBMP-PH had strong scavenging ability of DPPH·, hydroxyl (·OH), superoxide anion (O₂⁻·), and 2,2'-azo-bis-3-ethyl benzothiazoline 6-sulfonic acid (ABTS⁺·) free radicals, and the half inhibitory concentration IC₅₀ were 0.65, 1.16, 0.35, 0.57 mg/mL, respectively. When the protein concentration was 1 mg/mL, the total reducing power was 0.88. This paper provides a reference for the high-value utilization of bovine bone marrow resources and the development of peptide-originated functional foods.