Abstract:
Exopolysaccharides (EPS) synthesized by lactic acid bacteria (LAB) play a major role in the manufacturing of fermented dairy products, where they serve as thickener, emulsifying, or gelling agents. In this research exopolysaccharide production by Streptococcus thermophilus and Lactococcus lactis were studied in MRS agar medium supplemented with different type of carbon (glucose and lactose) and supplemented with nitrogen (peptone and beef extract). Next process is isolated the exopolysaccharides which is formed on medium surface using isopropyl alcohol (IPA). This process uses the principle of precipitation. Supplementation of MRS agar medium with carbon sources and nitrogen sources increased exopolysaccharides production on Streptococcus thermophilus and Lactococcus lactis. To analyzed the rheological behavior of EPS analysis is carried viscosity, shear stress, and shear rate using a rheometer Brookfields DVIII Ultra with two kinds of solvent, such as aquadest and NaCl 0,3 M. The result showed that using aquadest as solvent has the higher viscosity than using NaCl 0,3 M as solvent. Viscosity of EPS produced by Streptococcus thermophilus and Lactococcus lactis using aquadest as solvent were 270 cP and 285 cP. Viscosity of EPS produced by Streptococcus thermophilus and Lactococcus lactis using NaCl as solvent were 220 and 260 cP.
