Electrospray assisted fabrication of hydrogel microcapsules by single- and double-stage procedures for encapsulation of probiotics

The aims of this work were to investigate the influence of solution parameters on Ca-alginate/chitosan hydrogel microcapsules generated by electrospraying through a single stage procedure and subsequently employing it for encapsulation of live probiotics (Lactobacillus plantarum). The encapsulation yield of bacteria and their survival under simulated gastrointestinal conditions were evaluated. The protective role of chitosan, either included in the alginate matrix or deposited as an outer layer after formation of micro capsules, on the viability of bacteria was also investigated. Increasing the Na-alginate concentration resulted in larger and more uniform microcapsules. However, the size of microcapsules decreased and their size distribution became narrower by increasing surfactant concentration. Altering the concentration of Ca2+ and chitosan in the collector solution did not affect the size of microcapsules significantly. Encapsulation yield showed that almost 97 and 98% of probiotic bacteria were encapsulated viably within spherical Ca-alginate/chitosan microcapsules by single- and double-stage procedures, respectively. However, it was revealed that the different microcapsule matrices formed by the two fabrication procedures played an important role in survivability of bacteria during storage and exposure to acid. It was also found that the outer layer of chitosan, which was deposited on Ca-alginate microcapsules by double-stage procedure, more efficiently protected bacteria at low pH environments. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.