Exopolysaccharide production from whey lactose by fermentation with Lactobacillus delbrueckii ssp bulgaricus

Ropy Lactobacillus delbrueckii ssp. bulgaricus (strain RR) was used for production of exopolysaccharide in sweet whey and simulated whey permeate (SWP) supplemented with combinations of lactose, KH2PO4, NH4Cl, casamino acids, and mineral salts. Media were incubated at 32, 37, and 44 degrees C for 72h. Periodic adjustment of pH to similar to 6.2 increased viscosity and lactose utilization, and the free galactose and lactic acid in the media. The effect of pH adjustment was greater than that of supplementation with nutrients or minerals. Fermentation of supplemented SWP generally produced lower viscosities than did fermentation of supplemented sweet whey. After 24h fermentation, viscosity decreased in pH adjusted media. Viscosity of media was highest when incubation was at 32 degrees C and lowest with incubation at 44 degrees C.