• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1834-1845
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• 2018

The lactobacilli associated with a fermented goat milk product from Tajikistan were isolated to characterize their technological properties and antibiotic resistances in order to assess their suitability for development as starter cultures. In this study, twenty three strains were identified by 16S rRNA sequencing as typical dairy-associated lactic acid bacterial strains, i.e. L. plantarum, L. pentosus, L. delbrueckii, L. helveticus and L. paracasei. These strains were generally susceptible to most antibiotics tested in this study and this allowed a selection of strains as safe starters. The draft genomes of four representative strains were sequenced and the number of contigs of the four assembled genomes ranged from 51 to 245 and the genome sizes ranged from 1.75 to 3.24 Mbp. These representative strains showed differences in their growth behavior and pH-reducing abilities in in vitro studies. The co-inoculation of these Lactobacillus spp. strains together with a yeast Kluyveromyces marxianus MBT-5698, or together with the yeast and an additional Streptococcus thermophilus MBT-2, led to a pH reduction to 3.4 after 48 h. Only in the case of fermentation inoculated with the co-culture, the viscosity of the milk increased noticeably. In contrast, fermentations with single strains did not lead to gelation of the milk or to a decrease in the pH after 24h. The results of this study provide a comprehensive understanding of the predominant lactobacilli related to Tajikistani fermented milk products.

• Journal of Microbiology and Biotechnology
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• v.27 no.8
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• pp.1392-1400
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• 2017

Galactooligosaccharides (GOSs) are known to be selectively utilized by Bifidobacterium, which can bring about healthy changes of the composition of intestinal microflora. In this study, ${\beta}-GOS$ were synthesized using bifidobacterial ${\beta}-galactosidase$ (G1) purified from recombinant E. coli with a high GOS yield and with high productivity and enhanced bifidogenic activity. The purified recombinant G1 showed maximum production of ${\beta}-GOSs$ at pH 8.5 and $45^{\circ}C$. A matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the major peaks of the produced ${\beta}-GOSs$ showed MW of 527 and 689, indicating the synthesis of ${\beta}-GOSs$ at degrees of polymerization (DP) of 3 and DP4, respectively. The trisaccharides were identified as ${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-glucopyranose, and the tetrasaccharides were identified as ${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-galactopyranosyl-($1{\rightarrow}4$)-O-${\beta}-{\text\tiny{D}}$-glucopyranose. The maximal production yield of GOSs was as high as 25.3% (w/v) using purified recombinant ${\beta}-galactosidase$ and 36% (w/v) of lactose as a substrate at pH 8.5 and $45^{\circ}C$. After 140 min of the reaction under this condition, 268.3 g/l of GOSs was obtained. With regard to the prebiotic effect, all of the tested Bifidobacterium except for B. breve grew well in BHI medium containing ${\beta}-GOS$ as a sole carbon source, whereas lactobacilli and Streptococcus thermophilus scarcely grew in the same medium. Only Bacteroides fragilis, Clostridium ramosum, and Enterobacter cloacae among the 17 pathogens tested grew in BHI medium containing ${\beta}-GOS$ as a sole carbon source; the remaining pathogens did not grow in the same medium. Consequently, the ${\beta}-GOS$ are expected to contribute to the beneficial change of intestinal microbial flora.

• Korean Journal of Agricultural Science
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• v.5 no.2
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• pp.80-86
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• 1978

This study was carried out in order to know the effect of T. T. C. reaction on antibiotics, cleanser, disinfectants, pH, acidity and station of culture a bacterial Streptococcus thermophilus was used to 2.3.5-triphenyl tetrazolium chloride reduction test for the detection of residual antibiotics in milk were tested. The results obtained were summarized as follows. 1. The T. T. C. reaction was most sensitive in the group of penicillin as 0.02~0.05 IU and also it was less sensitive in Streptomycin and various broad antibiotics except Vibramycin, Synthomycin and Teramycin but it was least sensitive in Streptomycin group. 2. For ther T. T. C. reaction test on cleanser, the positive reaction was appeared above 0.7% of Hi-Ti and 0.1% of NaOH solution respectively. 3. For the T. T. C. test reaction on disinfectants, the positive reaction was occured on 200~500 ppm solution of sodium-hypochlorite and chloride-lime, 0.15~0.35% solution of phenol, cresol and Iode-K. 4. The optimum temperature was $35{\sim}37^{\circ}C$ and proper culturing time was 12 to 18 hours for propagation culturing. 5. The suspect positive reaction was tested above pH 5.0 and the positive reaction was appeared above 0.21% of acidity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1229-1236
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• 2009

This study was performed to examine the quality characteristics of the curd yogurt with different contents (0.5$\sim$2.0% (w/v)) of cherry powder (obtained from freeze-dried fruit of Prunus serrulata L. var. spontanea Max. wils.). Yogurt was fermented with two kinds of lactic acid bacteria (Streptococcus thermophilus, Lactobacillus bulgalicus) at $40^{\circ}C$ for 18h. During the period of 14 days of storage ($4^{\circ}C$, 14 days), acid production (pH and titratable acidity) of the yogurts increased significantly with the addition of cherry powder. The sugar content of the yogurts prepared with cherry powder increased but cherry powder yogurts presented lower viscosity values than the control. Hunter color values, lightness (L) and yellowness (b) of yogurt colors decreased as the concentration of cherry powder increased, whereas the redness (a) increased. Lactic acid bacteria of yogurts increased with the addition of cherry powder and all samples had increasing levels of lactic bacteria over the storage period. The sensory properties, such as flavor, taste, viscosity, and overall acceptability, of the yogurts containing the 1.0% cherry powder were superior to the control sample. Consequently, the optimal quality achieved in these experiments was yogurt with 1.0% cherry powder added.

• Journal of Life Science
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• v.25 no.1
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• pp.75-83
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• 2015

Curcuma longa L. (CL), a traditional medicinal plant, is well known as a functional food ingredient. The major component of CL is a curcumin of anthocyanin family that has multi-functions such as antimicrobial, anticancer, and antioxidant activity. In this study, fermented milk containing CL was prepared using a mixed strain culture (Bifidobacterium bifidus, Streptococcus thermophilus, Lactobacillus acidophilus), and its physicochemical properties were characterized. In addition, inflammatory cytokine-modulating effects of the fermented milk were also investigated. As regards the properties of fermented milk, the growth rate of lactic acid bacteria in fermented milk containing CL was found to be remarkably more rapid than control. During fermentation, caseins and whey proteins were observed to be partially hydrolyzed, and lactic acid and acetic acid were produced in larger amounts than in the control. The sensory score of fermented milk containing CL was lower than control, owing to its bitter taste and strong flavor. RAW 264.7 cells treated with CL fermented milk supernatant showed no cytotoxicity. Inflammatory cytokines such as tumor necrosis factor-alpha (TNF-${\alpha}$) and interleukin-6 (IL-6) were significantly produced by fermented milk with CL, compared to control. The secretion of nitric oxide (NO) from RAW 264.7 cells significantly increased relative to the control. Results from the present study suggested that CL could be used as a natural immunomodulating ingredient for making yogurts, beverages, and other products.

• Journal of Life Science
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• v.26 no.12
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• pp.1438-1445
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• 2016

Yeast can be post-contaminated by the equipment, producer, or air, and this can degrade yogurt quality. This study aimed to demonstrate the yeast inhibiting effect in fermented milk by adding Lactobacillus paracasei and Lactobacillus rhamnosus along with current fermenting lactic acid bacteria such as Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. A certain amount of yeast was added to fermented milk samples that were soon after stored at variable temperatures, and the number of yeast cells was counted periodically. The swelling phenomenon caused by the gas produced by the yeast in fermented products was also observed. In the two experiments, compared to the control, the L. paracasei- and L. rhamnosus-added-groups showed much slower rate of yeast appearance and lower frequency of swelling phenomena. This suggests that using a mixture of L. paracasei and L. rhamnosus in fermented milk inhibits the growth of yeast. Furthermore, if the products are stored at $10^{\circ}C$, post-acidification is rarely seen in the experimental group compared to the control group. This means that the organoleptic flavor can be kept consistent from the production day till the expiration day, resulting in improved organoleptic quality for customers. In other words, the use of L. paracasei and L. rhamnosus in fermented milk will result in the following positive effects: improvement in storage stability by delaying yeast appearance, increase in quality consistency by inhibiting post-acidification, and improved organoleptic quality by enhancing texture and flavor.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.161-167
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• 1998

Whey is by-product from natural cheese manufacturing process. For alcoholic fermentation, the initial lactose content and pH were adjusted to 4.5% and 4.2, respectively. Two strains of yeasts (Kluyveromyces marxianus, Saccharomyces cerevisiae) and seven strains of lactic acid bacteria (Lactobacillus brevis, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus lactis, Leuconostoc cremoris, Lactococcus lactis and Streptococcus thermophilus) were examined for their alcohol production and sensory acceptability. Ethanol content in the whey fermented by lactose-fermenting K. marxianus was 2.8% at 4th day of incubation and that fermented by nonlactose fermenting S. cerevisiae was 0.2%. In case of mixed fermentation with yeasts and tactic acid bacteria (LAB being inoculated at 0 hr), the maximum ethanol production was obtained in the sample inoculated at 16 hr by s. cerevisiae, and in the sample inoculated at 24 hr by K. marxianus. The optimum temperature was $37^{\circ}C$ for alcohol production under static condition. The production of $CO_2$ gas was higher in the whey fermented by K. marxianus (1.88%) than by S. cerevisiae (0.04%). The titratable acidity of the whey gradually increased with fermentation time and its content was 0.39% at 4th day of fermentation by K. marxianus and 0.52% by S. cerevisiae. Among seven strain of latic acid bacteria tested, Lactococcus lactis exerted synergistic effect for acid production with K. marxianus. Therefore, overall results suggestd that the combination of Lactococcus lactis and K. marxianus was best choice in fermenting cheese whey for edible purpose.

• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.57-62
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• 1982

The possibility of developing new kinds of lactic acid beverage from a malt syrup was studied. The optimum sugar concentration of malt syrup for the cultivation of lactic acid bacteria was $10^{\circ}Bx$. The acidity of the fermented malt syrup was improved by the supplement of yeast extract(0.5%) or sodium citrate(0.08%). Though the activity of Lactobacillus lactis in malt syrup was superior to other strains, sensory test indicated that the mixed culture of Lactobacillus lactis and Streptococcus diacetilactis was better because of masking malt flavour. The changes in acidity and viable cells of malt syrup during the lactic fermentation were not so good as skim milk medium, but malt syrup medium containing milk(50 : 50) was nearly similar to skim milk medium. In the sensory scores among samples, no significant differences(P<0.05) were noted between fermented milk and fermented malt syrup containing milk, but fermented malt syrup showed a poor quality. However fermented malt syrup was not inferior to marketing lactic fermented fruit juices with regards to the lactic acid fermented beverage type.

• The Korean Journal of Food And Nutrition
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• v.17 no.1
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• pp.1-7
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• 2004

Yoghurt base was prepared from skim milk added with 0.25∼2.0%(w/v) of chlorella extract powder and fermented with lactic acid bacteria(Streptococcus thermophilus : Lactobacillus casei = 1:1) at 37$^{\circ}C$ for 24 hours. Quality characteristics of the yoghurts were evaluated in terms of acid production, number of viable cell, color, texture property, and sensory property during lactic acid fermentation. The addition of 0.25% chlorella extract powder stimulated the growth of lactic acid bacteria which showed the highest number of viable cell counts(l.46${\times}$10$\^$8/ CFU/mL) after 12 hours incubation, and also enhanced the acid production which was pH 4.33 after 12 hours incubation. The L values(brightness) of the yoghurts containing chlorella extract powder were lower than control group, whereas the b values(yellowness) were higher. The hardness and gumminess of the yoghurt added with 0.25% chlorella extract powder were higher than others. Sensory scores of the yoghurt added with 0.25% chlorella extract powder were significantly higher than other groups in color, chlorella odor, sweet taste, chlorella taste, mouth feel, aftertaste and overall acceptability.

• Food Science and Preservation
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• v.24 no.5
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• pp.576-584
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• 2017

With the goal of developing a new functional fermentation milk using green tea powder (GP), milk was fermented with direct vat set (DVS) starter culture containing Streptococcus salivarius subsp. thermophilus, Lactobacillus paracasei and L. delbrueckii subsp. bulgaricus. We investigated fermentation characteristics and antioxidative activities of fermented milk supplemented with different concentrations (0.5, 1, 2, 3%) of GP. All samples were evaluated for pH, total acidity, viable cell count, and sugar contents. The pH of all samples decreased during fermentation, and the final pH ranged from 4.35 to 4.51. The acidity increased during fermentation, after the fermentation was completed, the titratable acidity was 0.8 to 1.1%. And viable cell count of all samples increased during fermentation, and the final viable cell count was 8.57 to 8.89 log CFU/mL. The sugar content decreased as the fermentation proceeded and finally reached 12 to $13^{\circ}Brix$. And increasing GP, decreased brightness and increased yellowness. Increasing GP concentration added to milk, improved DPPH free radical scavenging activity and ferric ion reducing activity of fermentation milk. The fermentation milk kept their pH, total acidity and viable cell counts standard of fermentation milk during the storage period at $4^{\circ}C$. These findings confirmed the possibility of development of the novel functional fermentation milk through the investigation of the quality characteristics of the fermentation milk added with GP.