Optimization of Microbial Rennet Encapsulation in Alginate - Chitosan Nanoparticles

Area of Science:

• Food Science and Technology
• Biotechnology
• Enzyme Engineering

Background:

• Rennet is crucial for cheese production, but its stability, especially during accelerated ripening, is a challenge.
• Enzyme immobilization via encapsulation offers a promising method to enhance enzyme stability and performance.
• Alginate and chitosan are commonly used biopolymers for encapsulation due to their biocompatibility and gelation properties.

Purpose of the Study:

• To optimize the encapsulation of rennet using alginate, chitosan, and calcium chloride (CaCl2).
• To evaluate the impact of encapsulation on rennet's stability, activity, and release kinetics.
• To characterize the physicochemical properties and interactions within the encapsulated system.

Main Methods:

• Response Surface Methodology (RSM) was employed to optimize alginate, chitosan, and CaCl2 concentrations for rennet encapsulation.
• Encapsulation efficiency, particle size, and zeta potential were measured at optimal conditions.
• Enzyme activity assays were conducted across various pH and temperature ranges.
• Infrared spectroscopy was used to confirm electrostatic interactions.
• Enzyme release kinetics were analyzed using the Korsmeyer-Peppas model.

Main Results:

• Optimal concentrations for alginate, chitosan, and CaCl2 were determined to be 0.04%, 0.1%, and 0.1%, respectively.
• The optimized encapsulation achieved an efficiency of 61.8%, with a particle size of 323 nm and zeta potential of 25 mV.
• Encapsulated rennet exhibited enhanced activity at different pH and temperature conditions compared to free rennet.
• The Korsmeyer-Peppas model indicated a Fickian diffusion mechanism for enzyme release.
• Infrared spectroscopy confirmed electrostatic interactions between rennet, alginate, and chitosan.
• No significant differences in kinetic parameters (Km and Vmax) were observed between free and encapsulated rennet.

Conclusions:

• Alginate-chitosan encapsulation effectively stabilizes rennet, improving its functional properties for food applications.
• The optimized encapsulation method provides a robust system for controlled enzyme release.
• The findings support the use of encapsulated rennet in accelerated cheese ripening processes, enhancing enzyme stability and activity.