Zn. Yang et al., Separation, purification and characterisation of extracellular polysaccharides produced by slime-forming Lactococcus lactis ssp cremoris strains, INT DAIRY J, 9(9), 1999, pp. 631-638
Five slime-forming Lactococcus lactis ssp. cremoris strains (ARH53, ARH74,
ARH84, ARH87 and B30) isolated from Finnish fermented milk viili have been
shown to produce viscous exopolysaccharides (EPSs) in skim milk cultures. T
he EPSs were separated and purified by treatment with trichloroacetic acid,
ethanol precipitation and dialysis. All EPSs were anionic and composed of
galactose, glucose and rhamnose of similar ratios. The H-1 NMR spectrum of
the EPS of strain ARH74 showed high similarity with that of strain SBT 0495
EPS, previously reported to consist of pentasaccharide repeating units wit
h a phosphodiester structural element. In dilute aqueous solutions (up to 0
.1 g dl(-1) of EPS), the EPSs showed polyelectrolyte effects, and they diff
ered in viscosity. At a higher concentration of EPS (1%, w/v), the EPS solu
tion showed a shear thinning behaviour, and the viscosity was temperature,
pH and salt dependent. Addition of 1% EPS (w/v) to skim milk resulted in a
significant increase in viscosity, and a gel formed at 40 degrees C. (C) 19
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