Double use of highly concentrated sweet whey to improve the biomass production and viability of spray-dried probiotic bacteria

• Sweet whey (SW) was used as a medium for biomass production and spray drying.
• Highly concentrated sweet whey (20~30% w/w) increased initial bacteria populations.
• Highly concentrated SW decreased the dependence of bacteria growth on casein peptone.
• Highly concentrated SW increased bacteria survival after spray drying.
• Bacteria in powders dried from highly concentrated SW had better storage stability.

Preservation of probiotics represents a challenge as the probiotic market increases. A simplified process from growth to drying of probiotics was investigated by utilizing sweet whey as a double-used medium. Its total solid content (TS) was increased in order to achieve one-step drying of bacterial cultures with higher levels of dry matter. Two probiotic strains, Lactobacilllus casei BL23 and Propionibacterium freudenreichii ITG P20, were used in this study. Interestingly, after increasing the TS of sweet whey from 5 to 20 or 30%, final population of both probiotic strains was higher, instead of being inhibited by the high osmolality. The final L. casei population was less dependent on casein peptone supplementation. The probiotic survival after spray drying was also improved when grown in culture media with 20 and 30% TS. Moreover, the probiotics in the powders from these higher TS culture media maintained considerably more stable viability over 4 month's storage at 4 °C.