Detarmination of exopolisaccharide (eps) and lactic acid production in molasses, whey and beet juice by Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus strains

DETARMINATION OF EXOPOLISACCHARIDE (EPS) AND LACTIC ACIDPRODUCTION in MOLASSES, WHEY AND BEET JUICE BYLactobacillus delbrueckii ssp. bulgaricus AND Streptococcusthermophilus STRAINS(M. Sc. Thesis)Neslihan YENIELGAZI UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYSeptember 2006ABSTRACTIn this research, it has been targeted to determine the production ofexopolysaccharide (EPS) and lactic acid in 1-5% molassesconcentration, whey, whey was supplemented with different subtancesand 1-5% beet juice by 3 strains of S. thermophilus and 2 of Lb.delbrueckii ssp. bulgaricus strains. Spectrophotometric method wereused to determine the EPS production by the strains. The amount ofEPS produced by S. thermophilus in these mediums were found to bebetwen 65-276 mg/L, 58-122 mg/L, 62-172 mg/L and 11-160 mg/L,respectively. İn the same mediums Lb. delbrueckii ssp. bulgaricusstrains produced EPS ranged betwen 109-290 mg/L, 97-151 mg/L, 152-232 mg/L and 12-260mg/L, respectively. Spectrophotometric methodwere used to determine the amout of lactic acid produced by thestrains. Lactic acid produced by S. thermophilus strains in themediums were found to be betwen 4,6-8,8 mg/mL, 5,1-7,9 mg/mL, 5,7-9,6mg/mL and 0,7-6,0 mg/mL, respectively. The amount of lactic acidproduced by Lb. delbrueckii ssp. bulgaricus strains in the mediumsmentioned were ranged between 5,5-10,1 mg/mL, 9,7-15,0 mg/mL, 13,7-15,4 mg/mL and 0,7-10,4 mg/mL respectively. It was observed that EPSproduction by these strains increased by the increasing the molassesconcentration, while lactic acid production were decreased. It was alsodetermined that whey samples supplemented with different subtances,EPS and lactic acid production by the strains were increased ascomparing with control mediums. While The EPS production by thestrains increased by the increasing beet juice concentration. From theresults the increasing of beet juice concentration were not effected onLactic acid productivity of the cultures.Science code :203-1.023Keywords :Lactobacillus delbrueckii ssp. bulgaricus,Streptococcus thermophilus, Lactic Acid,Exopolisaccharide (EPS), Molasses, Whey,Beet JuicePage Number :79Advisor :Prof.Dr.Yavuz BEYATLI