Probiotic Double-Coated Microencapsulation Using Spray Drying

Probiotic cell suspensions were subjected to double-coating microencapsulation with alginate and chitosan using the spray drying process, as previously reported^{15 (link)}. In brief, for inner capsulation, a 1.5% (w/v) alginate solution (Sigma-Aldrich) was prepared. Single stain and multi-strain probiotics at 10⁹ CFU/mL were combined separately with the alginate solution at a 1:5 (v/v) ratio. The alginate granules were harvested from the collecting vessel after being atomized through a spray dryer (Mini Spray Dryer B-290, Buchi) with an inlet temperature of 130 °C. The exterior microcapsule was made with a 0.5 percent (w/v) chitosan solution (Union Chemical 1986) in 100 mL of 1 percent (v/v) acetic acid (Merck KGaA). One gram of those powders was mixed with 100 mL of chitosan solution before being atomized in the spray dryer under the same conditions as described. The probiotic-containing double-coated powders were harvested from the collection vessel and stored at room temperature for six months before use in this study.