CONICET | Buscador de Institutos y Recursos Humanos

Galacto-oligosaccahrides (GOS) are units of galactose linked to glucose with a variable grade of polymerization (from 2 to 10). These compounds are important for their prebiotic properties, promoting the growth of beneficial bacteria in the gut microbiota and for their technological properties in the elaboration of food products. Preservation of lactic acid bacteria has technological interest for the starters production and elaboration of dehydrated foods, being lyophilisation, the more used method. However, dehydration by spray-drying has low cost and is the scaling is easier than for lyophilisation. Different sugars are added as protection agents in drying formulations to preserve bacterial structures and viability. In a previous work we demonstrated that commercial GOS could protect Lactobacillus bulgaricus during freeze-drying. However, the stability was limited to low relative humidities and temperatures. With this background, the aim of this work was improve the stability of spray-dried GOS by adding maltodextrin (MD) in the formulation. Different physical properties were studied: water sorption isotherm at room temperature, glass transition temperatures (Tg) by DSC, and molecular mobility was estimated by the spin-spin relaxation time (T2) measured by 1H-MNR. The addition of MD in the GOS formulation did not produce important changes in the water sorption isotherm. A high increase of Tg value was observed by adding MD. However, molecular mobility was slightly higher in presence of MD. An important advantage of the presence of MD was the retention of the glassy state up to 43% of relative humidity (RH) at room temperature. In contrast, formulations without MD remained in the glassy state up to 33% RH. These results indicate that the GOS-MD formulation could be used for the preservation of probiotic microorganisms by spray-drying