Pepsin immobilization on biochar by adsorption and covalent binding, and its application for hydrolysis of bovine casein

BACKGROUND The objective of this research was to compare the efficiency of pepsin immobilization by adsorption and covalent binding on biochar obtained from pupunha palm processing residue, and to use the immobilized enzyme in the hydrolysis of bovine casein. RESULTS The surface modification of biochar with glutaraldehyde was effective, as shown by Fourier transform infrared analyses and the texture properties of the carbons. Both activated and functionalized biochar showed high immobilization efficiency (>95%) and high enzyme-support binding capacity (>96 mg g(-1)). During the activity assays, the functionalized carbon showed a higher casein hydrolysis rate when compared to the enzyme immobilized by adsorption, with values of 39.17 U and 32.67 U, respectively, and c. 95% of the activity of the free enzyme, after 60 min. CONCLUSION The functionalization of the biochar led to a surface modification of biochar by the insertion of amine-aldehyde groups, which was responsible for the formation of strong interactions between the support material and the enzyme, thus providing a greater proteolytic activity when compared to immobilization by adsorption. The immobilized enzymes were able to maintain their proteolytic activity for more than seven cycles of reuse. (c) 2019 Society of Chemical Industry