Encapsulation of Lactobacillus acidophilus in moist-heat-resistant multilayered microcapsules

The development of state-of-the-art moist-heat-resistant microcapsules for a probiotic is described in this report. The survival of the heat-sensitive probiotic Lactobacillus acidophilus upon exposure to moist heat treatment was improved by encapsulating the bacterial cells in multilayered microcapsules, which were formed via a technique that combined electrospraying and fluidized bed coating. A composite composed of egg albumen (EA) and stearic acid (SA) was coated onto the L. acidophilus-encapsulating alginate microcapsules to produce the first shell layer. These microcapsules were subsequently coated with cassava starch granules while they were dried in a fluidized bed dryer using cassava pearls as the drying aid. The effect of the EA:SA ratio on the morphology, encapsulation efficiency (EE) and degree of moist-heat resistance (at 70 degrees C and 100% relative humidity for 30 min) of the microcapsules was investigated. The results showed that the EE of the microcapsules was greater than 90%. When the relative proportion of SA was increased, the survival rate of the cells encapsulated in the moist-heat treated microcapsules significantly improved. Compared with earlier reports, the current multilayered microcapsules conferred an extremely high degree of protection of the encapsulated cells upon moist heat exposure, with the cells suffering a loss of vitality of only 0.6 log CFU/g. These newly developed microcapsules can serve as a prototype encapsulation structure for the protection of other thermosensitive microorganisms and compounds used to fortify foods and feeds. (C) 2016 Elsevier Ltd. All rights reserved.