Evaluation of Streptococcus cremoris for preparing frozen concentrated starter cultures

Five strains of Streptococcus cremoris were investigated with respect to their usefulness for frozen concentrated biomass production. APLC medium assured high growth of 3 strains and highest cell concentration i.e. 4--6.7 g of fresh biomass from 1 litre of this medium. Two strains were sensitive to citrate present in APLC medium requiring a lowering of its dose to 0.5% in order to assure the highest biomass accumulation. The viability, endocellular proteolytic activity against casein and acidifying ability of frozen concentrates revealed that the physiological features of cells were preserved and remained unchanged during 2 and 12 weeks of storage at -30 degrees.