Controlled and rapid microreactor-assisted hydrolysis of sesame protein by a novel nanobiocatalyst; immobilized alcalase over activated sol–gel magnetic nanosupport

Abstract

In this study, sesame cake was valorized to produce sesame protein hydrolysate (SPH) with improved functional and antioxidant properties using a recoverable nanomagnetic immobilized Alcalase (ALC); the process was accelerated in the microreactor through a controlled-hydrolysis technique. For this purpose, silica-coated magnetic nanoparticles (Fe3O4@SiO2) were synthesized and functionalized with tetraethoxysilane (TEOS), N-(trimethoxysilylpropyl) ethylenediamine (TMSED), and finally activated with glutaraldehyde (GLU) to produce Fe3O4@SiO2-TMSED-GLU. Immobilization efficiency of ALC was 88.78 % in the optimum conditions of ALC concentration (1.23 mg/mL), immobilization period (119.12 min), and temperature (38.93 °C). The successful synthesis of Fe3O4@SiO2-TMSED-GLU-ALC magnetic nanobiocomposite (MNBC) was approved using FTIR, XRD, VSM, FESEM, EDX, and elemental mapping. The effective immobilisation of the enzyme was responsible for the decrease in the intensity of Fe3O4 diffraction peaks (in XRD) in MNBC and a reduction in saturation magnetization (in VSM) following ALC immobilisation. Microreactor-intensified hydrolysis in the optimized conditions of MNBC = 4.85 wt%, reaction time = 54.10 s, and temperature = 46.95 °C, led to a degree of hydrolysis = 7.19 %. After 10 hydrolysis cycles, MNBC had relative activity > 80 %, due to the appropriate covalent bonding between the enzyme and the support and the short duration of the process. The produced SPH had superior foaming capacity (113.09 %) compared to sesame protein (76.34 %). The emulsion activity and emulsion stability of SPH were 28.78 m2/g and 56.43 min, respectively, which were higher than those of the sesame protein.