Encapsulation of Lactobacillus bulgaricus in carrageenan-locust bean gum coated milk microspheres with double layer structure

- Lactobacillus bulgaricus was encapsulated in carrageenan-locust bean gum coated milk microspheres.
- Encapsulated L. bulgaricus showed better survival rate compared with free cells.
- Encapsulation of L. bulgaricus offers an effective delivery way to intestinal tract.

Carrageenan-locust bean gum coated milk microspheres were developed to encapsulate the probiotic Lactobacillus bulgaricus (L. bulgaricus) with the aim of enhancing the probiotic survival numbers during exposure to the adverse environmental conditions of the gastro-intestinal tract. The results indicated that milk microspheres with double layer structure could improve the stability of L. bulgaricus in simulated gastro-intestinal conditions. The viability of encapsulated L. bulgaricus did not change after 2 h incubation in simulated gastric fluid (SGF) pH 2.5. In SGF pH 2.0, the viability of encapsulated L. bulgaricus could be preserved more than 8 Log CFU/g after 2 h incubation. In 2 g/100 mL bile salt solution, encapsulated L. bulgaricus only suffered 1 Log CFU/g viability reduction after 1 h treatment, and 1.5 Log CFU/g viability reductions after 2 h treatment. Encapsulation could also improve the storage stability of encapsulated L. bulgaricus. The viability of encapsulated L. bulgaricus was kept constant after 1 month storage at 4 °C. Milk microspheres had high release rate for L. bulgaricus in simulated intestine fluid (SIF), which could be totally released in 45 min. This study presents a good encapsulation carrier which protects probiotic L. bulgaricus during exposure to adverse environment conditions.