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Lactobacillus plantarum and Bifidobacterium lactis were co-encapsulated separately with either inulin or resistant starch in Ca-alginate/chitosan microcapsules by electro-hydrodynamic atomization (EHDA). Encapsulation yield of core materials and their release profile were studied. Protective role of polysaccharide matrix on bacteria under gastrointestinal (GI) conditions and storage at 25, 4 or −18 °C were investigated. Encapsulation yield was calculated to be 98, 79 and 99 percent for bacteria, inulin and resistant starch, respectively. Ten percent of inulin was expelled from the Ca-alginate network into water after 24 h; however, no resistant starch was released. Chitosan coating reduced the release of inulin by up to 5 percent. Survival studies showed 5.90 ± 0.3 log CFU/g of Lb. plantarum and 7.19 ± 0.15 log CFU/g of B. lactis survived GI conditions in starch-containing microcapsules. Viability loss of Lb. plantarum was successfully restricted during storage at room temperature by encapsulation in Inulin-containing microcapsules as 6.33 ± 0.21 log CFU/g survived after 90 days storage. The findings revealed EHDA can be employed for co-encapsulation of probiotics and high molecular weight prebiotics in micron-sized capsules which could open up a new perspective for targeted delivery of live cells to the colon through foods.

In this study, we aimed to evaluate the possibility of obtaining natural high-resistant protein capsules from aqueous solution of whey protein containing transglutaminase (TG) enzyme through electrohydrodynamic atomization (EHDA) as an appropriate system, and freeze-drying (FD) technique as the control method for encapsulation of Lactobacillus casei. A stable cone jet was achieved in a certain electrical conductivity, surface tension, and viscosity values equal to 1681 ± 8.49 μS, 48.97 ± 0.02 mN/m, and 51.96 ± 0.78 cP, respectively. Spherical water-resistant capsules with an average diameter of 3.09 ± 1.04 μm were obtained through the EHDA process. A comparison between the EHDA and FD revealed higher encapsulation efficiency of the electrospraying technique as well as greater viability of L. casei under the simulated gastrointestinal (GI) tract. DSC results showed that the enthalpy of cross-linked samples was decreased by incorporating TG enzyme. In contrast to freeze-dried structures, electrosprayed capsules revealed better protection during the storage, especially in the second and third months.

The objective of this work was to investigate whether the use of unpurified agar-based fractions extracted from the seaweed Gelidium as microencapsulation matrices has an impact on probiotic protection during storage. Therefore, unpurified and pure agar and agarose-based microcapsules were produced through emulsification/internal gelation for the protection of Bifidobacterium pseudocatenulatum CECT 7765. Initially, agarose-based formulations with other biopolymers were evaluated, given the excellent oxygen barrier properties of this polysaccharide. The optimal combination in terms of probiotic protection was selected for further experiments and this agarose-based formulation was compared with microcapsules produced using both pure and unpurified agar-based fractions. The presence of other compounds (mainly proteins and polyphenols) in the unpurified agar fractions significantly improved the viability of these sensitive probiotic bacteria both at ambient and refrigerated storage conditions. Furthermore, the presence of impurities allowed the increase of solids content in the formulation giving raise to stronger gel particles, which could contribute to limited oxygen diffusion, thus, partly explaining the improved protection. Therefore, this work demonstrates the potential of more cost-effective less purified carbohydrate-based fractions for probiotic protection., This work was financially supported by the “Agencia Estatal de Investigación” and co-funded by the European Union's Horizon 2020 research and innovation programme (ERA-Net SUSFOOD2) and the European Union's Seventh Framework Program under the grant agreement no 613979 (MyNewGut). Marta Martinez-Sanz, Maria José Fabra and Laura G. Gómez-Mascaraque are recipients of a Juan de la Cierva (IJCI-2015-23389), Ramon y Cajal (RYC-2014-158) and predoctoral (BES-2013-065883) contracts, respectively, from the Spanish Ministry of Economy, Industry and Competitiveness.