• Food Science of Animal Resources
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• v.33 no.6
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• pp.787-795
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• 2013

This study was carried out to investigate the characteristics of goat and cow milk yogurts containing high-exopolysaccharide fermented by Streptoccous thermophilus LFG isolated from kefir. The pH of cow milk yogurt was higher than that of goat milk yogurt. The contents of lactic acid was greater in goat milk yogurt (743.9-1043.8 mg/100 g) than in cow milk yogurt (441.6-709.9 mg/100 g). The numbers of survival lactic acid bacteria were the greatest in goat milk yogurt fermented by Str. thermophilus LFG. Viscosity was greater in cow and goat milk yogurts cultured by Str. thermophilus LFG than in yogurts by Str. thermophilus TH3. Syneresis of yogurt fermented by Str. thermophilus LFG was 9.6-16.1% and 28.2-31.8% in yogurt fermented by Str. thermophilus TH3 after 10 d storage at $4^{\circ}C$. Flavor compounds identified from goat milk were acetone, ethylbutanoate, ethyl-3-methylbutyrate, ethyl-2-butenoate and ethylhexanoate, and those from cow milk were ethylbutanoate, acetone, 2-heptanone and acetoin. Flavor compounds detected from goat milk and cow milk yogurts were acetic acid, butanoic acid, butanol, diethylcarbinol, acetone, diacetyl, decane, 2-methyl-3-pentanone, hexanal, 2-heptanone, acetoin, benzaldehyde, dimethyldisulfide, and dimethyltrisulfide. In sensory evaluation, overall preference and texture values were higher in goat milk yogurt fermented by Str. thermophilus LFG than in cow milk yogurts and the yogurt fermented by mixed culture resulted in the highest score.

• Food Science of Animal Resources
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• v.29 no.2
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• pp.143-150
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• 2009

This study was carried out to investigate the properties of crude exopolysaccaride (CEPS) produced by Streptococcus thermophilus LFG in goat milk. The yields of CEPS from yogurt cultured with Str. thermophilus LFG were greater at higher temperatures $(40-45^{\circ}C)$ than at lower temperatures $(30-35^{\circ}C)$. Goat milk yogurt had lower viscosity values than cow milk yogurt. However, the CEPS yield was higher in goat milk yogurt than in cow milk yogurt. The yields of CEPS from yogurt were also higher in cultured milk containing 3% glucose (14-21%), and 3% sucrose (4-16%) relative to the control yogurt. Antioxidant activities were higher in goat milk yogurt supernatant (21%) and its CEPS (28%) than cow milk yogurt supernatant (11%) and its CEPS (24%). The amino acid contents of CEPS were higher in yogurt using goat milk than that using cow milk. The CEPS extracted from goat milk yogurt produced by Str. thermophilus LFG consists of carbohydrate (37% w/w) and protein (63% w/w). The CEPS consisted of monosaccharides such as glucose 56.45% (w/w), galactose 42.35% (w/w), galactosamine 1.37% (w/w), glucosamine 1.09% (w/w) and fucose 0.27% (w/w).

• Food Science of Animal Resources
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• v.28 no.1
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• pp.82-90
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• 2008

Two strains of pure lactic acid bacteria capable of forming both acid and slime were isolated from the kefir made of goat milk. The isolated strains observed by morphological and physiological properties, and their 16S rDNA partial sequence were identified as Streptococcus salivarius subsp. thermophilus(LFG-1) and Lactococcus lactis subsp. lacits(LFG-2) with over 99% homology. The optimum temperature of Str. salivarius subs. thermophilus LFG-1 for growth was $40-45^{\circ}C$, and its generation time was 40.6 minutes. The final pH of cultured broth by Str. salivarius subsp. thermophilus LFG-1 and the commercial strain Str. thermophilus Body-1 for 24hr at $37^{\circ}C$ were 4.30 and 4.55, respectively. The coagulative activity of Str. salivarius subsp. thermophilus LFG-1 was almost as strong as that of commercial strain Str. thermophilus Body-1. However, the LFG-2 strain showed lower coagulative activity than Str. thermophilus Body-1. The survival rate of lactic acid bacteria were between 22-29% in 0.3% bile extract. At pH 1.0 all of the bacteria were killed, and most of lactic acid bacteria died against pH 3.0. However, all lactic acid bacteria survived well at pH 4.5.