Evaluation of the effect of CaCl2 and alginate concentrations and hardening time on the characteristics of Lactobacillus acidophilus loaded alginate beads using response surface analysis

This article describes preparation and characterization of beads of alginate containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Fourteen formulations using different alginate (ALG) and CaCl2 concentrations as well as hardening times were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology, encapsulation efficiency and bacterial viabilities in acid (pH 1.8, 2 hours) condition. The results showed that spherical beads with narrow size distribution ranging from 1.32±0.04 to 1.70±0.07 mm were achieved with encapsulation efficiency higher than 98%. Surface response analysis revealed that alginate concentration was the important factor for the size, shape and encapsulation efficiency of prepared beads. Furthermore, survived bacteria after acid exposure in all prepared beads (63-83%) were significantly higher than those of untreated cells (39%) and enhanced by increasing alginate concentration. Surface response analysis revealed that the effect of all three factors of alginate and CaCl2 concentrations as well as hardening times were significant in acid viability, however alginate concentration played the most important role according to its regression coefficient. Among alginate and CaCl2 concentrations as well as hardening times, alginate concentration was the most variable in the characteristics of Alginate beads.