The fermented dairy products produced by various microorganism’s activity provide valuable
nutrients for human. Fermentation affects the physicochemical and organoleptic characteristics
of foods as well as human health. In the present review, we describe the production of vitamin B12 in
a fermented dairy product by Propionibacterium species. The effect of the process variables on vitamin
B12 production in fermented dairy products e.g. pH, temperature, different carbon and nitrogen
sources as well as the type and size of inoculum, the fermentation time and fermentation strategy, etc.
are discussed. Finally, fermentation strategy, inoculum preparation of Propionibacterium freudenreichii
subsp. Shermanii, methods of determining biomass and Vitamin B12 concentration are reviewed
and their effects on vitamin B12 production are mentioned. Propionibacteria are so popular
due to their unique characteristics such as being safe, convenient and economical. Among all the
highest efficiency was observed by P. freudenreichii. To achieve this purpose, some appropriate situations
need to be considered. The best carbon source for this bacterium to produce biomass is lactate,
the suitable pH for growth of the Propionibacterium species is in the range of 6 to 7 and the fed-batch
is most preferable for vitamin B12 production.