Microencapsulation of Microbial Transglutaminase by Ultrasonic Spray-Freeze Drying

Microencapsulation of partially purified microbial transglutaminase (mTG) was investigated using ultrasonic spray-freeze drying (USFD), and the optimum coating materials (gum arabic, maltodextrin, inulin) ratio and the process parameters (flow rate and nozzle frequency) were determined using a D-optimal combined design. Also, the microencapsulated samples by USFD were compared with microencapsulated samples by conventional freeze drying (CFD) and conventional spray drying (CSD) in terms of microencapsulation efficiency, enzyme stability at extreme pH and high temperature conditions, and the presence of metal ions, physical (moisture content, particle morphology, particle and pore size, surface area, pore volume distribution, density and flow properties, caking degree, color), and reconstitution (wettability and solubility) properties. As a result, the optimum coating materials composition was determined as 60% gum arabic and 40% inulin, and process conditions were found to be flow rate of 6.83 ml/min and nozzle frequency of 48 kHz applying desirability function method. Microcapsules with smaller particle size, pore volume, and porosity, with lower moisture content and good reconstitution characteristics, were obtained by USFD with a maximum microencapsulation efficiency of similar to 97%.