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Bifidobacterium BB-12 intended for use in functional dairy products are selected traditionally by taking into account a proper technological performance. Therefore, in vitro simulated gastrointestinal conditions should be studied to obtain essential information about the potential probiotic properties of bifidobacteria since there is a lack of this study. Our study aimed to evaluate the protective effects of probiotic and symbiotic soft fresh cheeses matrices, both manufactured from the concentrated milk from the second stage of block freeze concentration process, on Bifidobacterium BB-12 survival under in vitro simulated gastrointestinal conditions. These simulated assays were done consecutively including all gastrointestinal tract compartments, such as the mouth, esophagus-stomach, duodenum, and ileum. After the simulated gastrointestinal conditions, it was possible to verify a positive effect on the viable cells count and survival rate of Bifidobacterium BB-12 in probiotic cheese followed by symbiotic cheese, this last one also with inulin addition. Finally, both novelty kinds of cheese can be considered a protective matrix on Bifidobacterium BB-12 survival.

Lactose-free probiotic powders were obtained by mixing Bifidobacterium BB-12 suspensions with lactose-free milk powder or lactose-free milk powder and prebiotics (inulin or oligofructose). A thorough investigation was performed to know their water sorption properties and physical and thermal characteristics. By evaluating the water sorption properties, the Peleg model fitted well to the experimental sorption data, showing that the equilibrium moisture content of powders increased as the relative humidity increased. The isotherm found for all samples was a Type III Isotherm, commonly observed in most foods. For both morphology and particle size, the use of different carrier agents affected these properties; however, all the spray-dried powders presented good size to be added in food products. X-ray diffraction and Raman spectroscopy showed us amorphous structure for all powders, and typical bands of the milk constituents and sugars, respectively. Regarding the spray-dried powders thermal properties, it was possible to confirm that the addition of prebiotics gave higher thermal stability, highlighting the sample produced with inulin. We concluded that a good quality of lactose-free milk based probiotic powder could be obtained using spray drying technique, with great potential to be applied in lactose-free dairy products. We are grateful to Coordination of Improvement of Higher Education Personnel (CAPES, Brazil) [CAPES-PRINT, Project number 88887.310560/2018-00]; to National Council for Scientific and Technological Development (CNPq, Brazil) by the financial support [CNPq, 405965/2016-8], and to Coordination of Improvement of Higher Objectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura