Comparative Evaluation of Extrusion and Emulsification Techniques for Alginate-Based Microencapsulation of Bifidobacterium longum

Abstract

Microencapsulation can enhance probiotic viability by shielding cells during processing and digestion. This study investigated the encapsulation of Bifidobacterium longum using two different techniques extrusion and emulsification with sodium alginate (1% and 2% w/v) as the wall material. Probiotic cultures were prepared and encapsulated by dropping cell-alginate mixtures into CaCl₂ (extrusion) or dispersing into oil with CaCl₂ (emulsification), followed by freeze-drying. The resulting microcapsules were characterized for size, morphology, moisture content, hygroscopicity, encapsulation efficiency, and cell viability. Encapsulation efficiencies were high for both methods (ranging ~88-97%), with the extrusion method at 1% alginate achieving the highest efficiency (~96.6%) and viability (~8.7 log cfu/g). Emulsification produced slightly lower efficiencies (91-94%) and viable counts (~8.0 log), but all formulations maintained probiotic counts well above the recommended therapeutic minimum of 107 cfu/g. Capsule size depended on method and alginate concentration: extrusion yielded larger, spherical beads (~1.5 mm), while emulsification produced smaller, irregular capsules (~0.5 mm). Higher alginate concentration (2%) led to significantly increased capsule size in both methods (p