Effects of media, heat adaptation, and outlet temperature on the survival of Lactobacillus salivarius NRRL B-30514 after spray drying and subsequent storage

Abstract

Effects of drying media, heat adaptation, and outlet temperature on the survival of Lactobacillus salivarius NRRL B-30514 after spray drying and during subsequent storage were studied in this work. Drying media were studied for 200 g/L reconstituted skim milk (RSM), 180 g/L RSM+40 g/L sucrose+40 g/L trehalose, and 180 g/L RSM+40 g/L lactose+40 g/L trehalose (RSMLT). Outlet temperatures were studied from 70 to 100 °C, and heat adaptation was studied by heating cell suspensions at 50 °C for 15 min before spray drying. Overall, the reduction of viable L. salivarius in all media with and without heat adaptation decreased with the decrease of outlet temperature. For treatments with disaccharides, heat adaptation additionally improved the bacterial viability after spray drying. The lowest (0.56 log CFU/g) and highest (2.16 log CFU/g) reduction was observed for cells suspended in RSMLT with heat adaptation and those in RSM without heat adaptation, respectively. A higher outlet temperature resulted in a lower water activity of spray-dried L. salivarius and the improved survivability after 2-week storage in a desiccator at 21 °C. Therefore, the studied parameters can be combined to improve the production of spray-dried probiotics.