CONICET | Buscador de Institutos y Recursos Humanos

Relationships between exopolysaccharide (EPS) production (amount, molecular mass and sugar composition of the EPS) by different Streptococcus thermophilus strains as a functional starter culture, and textural characteristics (viscosity) of fermented milk and yoghurt have been studied. Five interesting heteropolysaccharide-producing strains have been tested. Both S. thermophilusStreptococcus thermophilus strains as a functional starter culture, and textural characteristics (viscosity) of fermented milk and yoghurt have been studied. Five interesting heteropolysaccharide-producing strains have been tested. Both S. thermophilusS. thermophilus LY03 and S. thermophilus CH101 produced the highest amounts of EPS and also displayed the highest apparent viscosities in fermented milk. S. thermophilus ST 111 and S. thermophilus STD differed considerably in EPS yields, but not in apparent viscosities of fermented milk. In addition, S. thermophilus ST 111 displayed a high variability in EPS amounts when cultivated in milk. In milk medium, S. thermophilus LY03 produced two heteropolysaccharides, a high-molecular-mass (HMM) EPS and a low-molecularmass (LMM) EPS of the same composition ðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPSS. thermophilus CH101 produced the highest amounts of EPS and also displayed the highest apparent viscosities in fermented milk. S. thermophilus ST 111 and S. thermophilus STD differed considerably in EPS yields, but not in apparent viscosities of fermented milk. In addition, S. thermophilus ST 111 displayed a high variability in EPS amounts when cultivated in milk. In milk medium, S. thermophilus LY03 produced two heteropolysaccharides, a high-molecular-mass (HMM) EPS and a low-molecularmass (LMM) EPS of the same composition ðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPSS. thermophilus ST 111 and S. thermophilus STD differed considerably in EPS yields, but not in apparent viscosities of fermented milk. In addition, S. thermophilus ST 111 displayed a high variability in EPS amounts when cultivated in milk. In milk medium, S. thermophilus LY03 produced two heteropolysaccharides, a high-molecular-mass (HMM) EPS and a low-molecularmass (LMM) EPS of the same composition ðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPSS. thermophilus ST 111 displayed a high variability in EPS amounts when cultivated in milk. In milk medium, S. thermophilus LY03 produced two heteropolysaccharides, a high-molecular-mass (HMM) EPS and a low-molecularmass (LMM) EPS of the same composition ðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPSS. thermophilus LY03 produced two heteropolysaccharides, a high-molecular-mass (HMM) EPS and a low-molecularmass (LMM) EPS of the same composition ðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPSðGal=Glu=GalNAc ¼ 3:4:1:4:1:0Þ: S. thermophilus ST 111 produced only a HMM-EPS ðGal=Rha ¼ 2:5:1:0Þ; while S. thermophilus CH 101 ðGal=Glu ¼ 1:0:1:0Þ; S. thermophilus ST 113 ðGal=Glu=Rha=GalNAc ¼Gal=Rha ¼ 2:5:1:0Þ; while S. thermophilus CH 101 ðGal=Glu ¼ 1:0:1:0Þ; S. thermophilus ST 113 ðGal=Glu=Rha=GalNAc ¼ 1:7:3:9:1:5:1:0Þ and S. thermophilus STD ðGal=Glu=Rha=GalNAc ¼ 3:5:6:2:1:2:1:0Þ produced only LMM-EPS. Both HMM-EPS and LMM-EPS solutions (S. thermophilus LY03) demonstrated a pseudoplastic character; HMM-EPS solutions of 0.2% (m/v) displayed a high consistency as well. Although its production of high EPS amounts, S. thermophilus LY03 resulted in relatively thin yoghurts, so that texture values did not directly correlate with EPS production capacity. Once structure/function relationships are known, one can determine the molecular properties of the isolated and purified EPS (molecular size, structural characteristics) from candidate strains to predict their potential in texture formation. For a final selection of interesting EPS-producing starter strains one should test the EPS production under yoghurt manufacturing conditions.:7:3:9:1:5:1:0Þ and S. thermophilus STD ðGal=Glu=Rha=GalNAc ¼ 3:5:6:2:1:2:1:0Þ produced only LMM-EPS. Both HMM-EPS and LMM-EPS solutions (S. thermophilus LY03) demonstrated a pseudoplastic character; HMM-EPS solutions of 0.2% (m/v) displayed a high consistency as well. Although its production of high EPS amounts, S. thermophilus LY03 resulted in relatively thin yoghurts, so that texture values did not directly correlate with EPS production capacity. Once structure/function relationships are known, one can determine the molecular properties of the isolated and purified EPS (molecular size, structural characteristics) from candidate strains to predict their potential in texture formation. For a final selection of interesting EPS-producing starter strains one should test the EPS production under yoghurt manufacturing conditions.S. thermophilus LY03) demonstrated a pseudoplastic character; HMM-EPS solutions of 0.2% (m/v) displayed a high consistency as well. Although its production of high EPS amounts, S. thermophilus LY03 resulted in relatively thin yoghurts, so that texture values did not directly correlate with EPS production capacity. Once structure/function relationships are known, one can determine the molecular properties of the isolated and purified EPS (molecular size, structural characteristics) from candidate strains to predict their potential in texture formation. For a final selection of interesting EPS-producing starter strains one should test the EPS production under yoghurt manufacturing conditions.S. thermophilus LY03 resulted in relatively thin yoghurts, so that texture values did not directly correlate with EPS production capacity. Once structure/function relationships are known, one can determine the molecular properties of the isolated and purified EPS (molecular size, structural characteristics) from candidate strains to predict their potential in texture formation. For a final selection of interesting EPS-producing starter strains one should test the EPS production under yoghurt manufacturing conditions.

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