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β-glucans come from cereals that have been located within compounds with prebiotic activity. They have presented several bioactivities that have determined their high functional value. The aim of this study was to identify the influence of oat β-glucan on the survival and proteolytic activity of Lactobacillus rhamnosus GG in a milk fermentation through an experimental design to optimize the process. For β-glucan extraction after dry milling of oats, two methods were applied: with and without enzymatic inactivation of the semolina. The highest extraction yield (45.25 g/L) was obtained with enzymatic inactivation. For the optimization of survival and proteolytic activity, a central design composed of axial points with two factors on three levels was used. Control factors were β-glucan and inoculum concentrations. According to response surface, the best survival growth rate of probiotic was observed with 4.38% of inoculum and 22.46 g/L of β-glucan, and the highest production of free amino groups was observed with 4.18% of inoculum and 22.71 g/L of β-glucan. Thus, β-glucan promotes the proteolytic activity of Lb. rhamnosus GG in milk fermentation. [ABSTRACT FROM AUTHOR]

Fucosyl-oligosaccharides are natural prebiotics that promote the growth of probiotics in human gut and stimulate the innate immune system. In this work, the release of α-lfucosidase by Lactobacillus rhamnosus GG, and the use of this enzyme for the synthesis of fucosyl-oligosaccharides were investigated. Since α-lfucosidase is a membrane-bound enzyme, its release from the cells was induced by addition of 4-nitrophenyl-α-l-fucopyranoside (pNP-Fuc). Enzyme activity associated with the cell was recovered at 78% of its total activity. Fucosyl-oligosaccharides where synthesized using α-l-fucosidase extract and pNP-Fuc as donor substrate, and D-lactose or D-lactulose as acceptor substrates, reaching a yield up to 25%. Fucosyllactose was obtained as a reaction product with D-lactose, and its composition was confirmed by mass spectrometry (MALDI-TOF MS). It is possible that the fucosyl-oligosaccharide synthesized in this study has biological functions similar to human milk oligosaccharides. [ABSTRACT FROM AUTHOR]