Optimization of Electrospray-Assisted Microencapsulation of Probiotics (Leuconostoc lactis) in Soy Protein Isolate-Oil Particles Using Box-Behnken Experimental Design

This research aimed to evaluate and optimize the electrospraying process of microencapsulating the probiotic strain, Leuconostoc lactis (NCDC 200), in a soy protein isolate (SPI) and sunflower oil (SO) combination matrix. In the present study, experimentation was conducted to establish the concentrations of SPI (12–15% w/v), SO (0–5% w/v), and the voltage range (10–15 kV) for the electrospraying operations. Probiotic characteristics, namely, the loss of viability of probiotic cells and encapsulation efficiency, were studied using Box-Behnken design, and specific runs were compared with the freeze-drying process. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used for microcapsule characterization. The optimized electrospraying process conditions were found to be 13.13% (w/v) SPI, 10.24 kV voltage, and 4.77% (w/v) of SO, for which a viability loss of 0.663 log CFU/g (< 1 log CFU/g) and encapsulation efficiency of 92.93% were achieved. Increasing SPI and SO concentration and decreasing the process voltage significantly reduced the viability loss and improved encapsulation efficiency. The study found no significant difference between freeze-drying and electrospraying techniques for encapsulating probiotics in terms of encapsulation efficiency and viability loss for the optimized formulation. The SEM micrographs confirmed the spherical morphology of electrosprayed microcapsules, and FTIR was useful for characterizing and analyzing the protein-lipid interactions in different microcapsules. The present study could establish the protective effect rendered to probiotic cells by combining SPI and SO at specific concentrations during electrospraying. Graphical abstract: [Figure not available: see fulltext.].