Immobilized alcalase on ZIF-L as a biocatalyst for protein hydrolysis

• Alcalase immobilized on ZIF-L demonstrated high adsorption capacity of 672.1 mg/g at 40°C. • Freundlich and pseudo-first-order models best described the adsorption and kinetic data. • Immobilized Alcalase retained over 90% activity after 70 days, indicating good stability. • Protein hydrolysates from Scenedesmus sp . showed antioxidant activity with 82.75% DPPH scavenging. Immobilization of alcalase on a ZIF-L (A@ZIF-L) support was explored for its potential application in producing hydrolysates of proteins extracted from microalgae. The immobilized enzyme was characterized using FTIR, XRD, SEM, and TGA, and the maximum adsorption capacity was found to be 672.1 ± 5.5 mg g⁻¹ at 40°C. Adsorption equilibrium data indicated that alcalase physically adsorbed onto the ZIF-L, with the isotherm well described by the Freundlich model. The adsorption kinetics aligned best with the pseudo-first order model, suggesting that both film and intraparticle diffusion were significant. The hydrolytic activity of the immobilized A@ZIF-L was initially tested using BSA as a substrate. A diffusion-reaction model was developed and numerically solved to describe the reaction, with results confirming the presence of mass transfer limitations in the early stages of hydrolysis. The stability of the immobilized enzyme was demonstrated by retaining over 90% of its initial activity after being stored at 4°C for 70 days. Furthermore, the immobilized A@ZIF-L was used to hydrolyze protein extracts derived from Scenedesmus sp . microalgae. The bioactivity of the resulting protein hydrolysates was characterized, showing a total phenolic content of 29.1 ± 0.6 mg GAE g⁻¹ and a radical scavenging activity of 82.75 ± 2.20%. These findings highlight the potential of Alcalase-based biocatalysts for applications in the food industry.