Immobilization of probiotic cells

Abstract

This study investigated the impact of encapsulating “Lactobacillus acidophilus” (LA-05) in alginate beads on its viability under thermal and acidic stress conditions, with a focus on its potential application in functional food products. Probiotic cells were immobilized using ionic gelation with the method of extrusion, forming beads and stored into a calcium chloride solution. The survival of both free and encapsulated cells was evaluated under thermal stress at 72 °C, across various pH levels (3,5 and 6.7) and under simulated gastrointestinal digestion. Results indicated that, initially, free cells exhibited higher viability than encapsulated cells, likely due to osmotic or mechanical stress during encapsulation process. However, encapsulated cells consistently outperformed free cells throughout the digestion process. Specifically, encapsulated LA-05 cells maintained significantly higher viability in both gastric and intestinal phases compared to free cells, demonstrating the protective effect of alginate encapsulation against harsh environment conditions. Despite this advantage, total loss of viability occurred under extended exposure to extreme conditions, highlighting the sensitivity and the lack of tolerance of the probiotics to these stressors. It is recommended that future studies focus on minimizing stress during bead formation and consider alternative storage media, such as milk which contains the essential nutrients for the probiotics to survive, offering a better medium solution. Overall, the study underscores the potential of alginate encapsulation for improving probiotic survival in functional foods, while emphasizing the importance of process optimization to maximize health benefits and industrial applicability.