ii Dedication

“Say: Truly, my prayer and my service of sacrifice, my life and death are (all) for Allah, The Cherisher of the Worlds” Al Qur’an 6:1 iii This thesis focused on the study of the influence of different exopolysaccharide types produced by two strains of Streptococcus thermophilus on the physical properties of fermented milk. First, the fermentation factors affecting EPS production were studied to ascertain required carbon source and environmental conditions which would support their production. Higher fermentation temperature (42°C) resulted in a greater cell growth and EPS production. EPS production was growth associated in glucose or lactose-containing M17 medium. The examined strains appeared to be able to utilize galactose for the EPS assembly and produced comparable amounts of EPS, albeit restrictive cell growth. The EPS production of the two strains was comparable, ranging from ~100 t