Double layer encapsulation of Lactobacillus acidophilus by Emulsion and spray-drying Techniques: Study of characteristics and survival of microcapsules under simulated gastrointestinal conditions

With increasing public awareness, the demand for healthy foods has increased. Low resistance of probiotic bacteria against adverse environmental conditions is one of the most important factors limiting the production and development of probiotic products. Encapsulation by enclosing probiotic cells can increase stability against limiting factors such as gastric acidity. In this study, the efficiency of double layer encapsulation with sodium alginate and chitosan by spray drying and emulsion methods on the stability of Lactobacillus acidophilus under simulated gastric conditions (pH=2) during 0, 30, 60, 90 and 120 minutes were examined. The size of the microcapsules was determined by the particle size analyzer and their morphology using a scanning electron microscope (SEM). The obtained growth curve showed that the bacteria enter a stationary growth phase 40 to 42 hours after inoculation. The size of the microcapsules obtained from the emulsion method were significantly (p≤ 0.05) smaller than the spray drying method. The morphology of the microcapsules was spherical to oval, and the samples obtained from the spray drying method had a shrinked surface. The highest survival was shown by emulsion encapsulated samples with a decrease of 1.9 logarithmic cycles, followed by spray dried encapsulated bacteria with a reduction of 2.4 logarithmic cycles. The lowest survival rate was related to the control sample (free bacteria) with a decrease of 3.83 logarithmic cycles. Encapsulation of Lactobacillus acidophilus probiotic bacteria by the emulsion technique by creating appropriate stability under simulated gastric conditions is a suitable method to obtain probiotic products enriched with this bacterium.