Microencapsulação de Bifidobacterium longum 51A incorporada em farinha de aveia

The aim of this study was to investigate the effect of microencapsulation on the viability and functionality of Bifidobacterium longum subsp. longum 51A. For this purpose, microcapsules of alginate with resistant starch and alginate with chitosan were prepared by emulsification technique and, by spray drying technique, microcapsules were prepared using powdered skim milk reconstituted as matrix. The microcapsules were characterized by Atomic Force Microscopy and Transmission Electron Microscopy and the viability of microencapsulated cells was determined by plate count during 8 times of storage (-20 ° C / 90 days) and under simulated conditions of the gastrointestinal tract. Cellular injuries were also analyzed using fluorescence of two probes followed by flow cytometry and the hydrophobicity of microencapsulated cells by spray drying was evaluated. And, finally, the viability of the free and encapsulated cells in oatmeal was determined for 90 days at 4° C. The results indicated the size variability of the microcapsules, all were less than 200 m, and the spray dried ones were the smallest, with approximately 17 m. During storage (90 days/ -20°C), B. longum 51A remained above 7,51 ± 0,25 log CFU g-1 in all microcapsules evaluated. However, only the microcapsules made by spray drying ensured viability under simulated gastrointestinal conditions and also ensured the recovery of hydrophobicity during storage. Furthermore, the microstructure analysis indicated that in these capsules the surface is homogeneous and with rare cells without coating by the matrix material. In addition, flow cytometry has demonstrated that spray drying microencapsulation keeps most cells intact and uninjured after drying and showed the limitation of plate count method to assess cell viability, indicating that even when injured the bacterial cells grow in culture medium. It was finally obtained that the microcapsules produced by spray drying are suitable to be added in oatmeal and that the cells remain stable in this product during the evaluated 90 days of storage.