• The Korean Journal of Food And Nutrition
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• v.7 no.2
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• pp.151-158
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• 1994

This study was carried out to clear up the cause of low-acid producing phenomenon occurred In non-fat dry milk during liquid-yoghurt fermentation by Lactobacillus case, and to present its improving methods. All samples of non-fat dry milks which were low in TCA-soluble peptides showed low-acid production, but those high in TCA-soluble peptides showed high-acid production. The addition of trypsin-hydrolysate of Na-caseinate to non-fat dry milk showed some improving effect on acid production but that of papain-hydrolysate did not show any improving effect and that of bacterical neutral protease-hydrolysate showed some inhibitory effect. The improving effects on growth and acid production of lactic acid bacteria were more prominent when the trypsin-hydrolysate of Na-caseinate was added. to such fermenting system in which the levels of TCA-soluble peptides and the proteolytic ability of starter bacteria were abnormally low. The liquid-yoghurt made with non-hydrolysed Na-caseinate and defective non-fat dry milk showed precipitate occurrence but that with trypsin-hydrolysate of Na-caseinate and defective non-fat dry milk did not make any precipitate during storage as with normal non-fat dry milk.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.340-344
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• 1993

Gel type yoghurts from 5 representative manufacturers were collected at market and evaluated their physico-chemical properties during storage at $5^{\circ}C$. The range of pH, acidity, Brix and viscosity of each product were $3.87{\sim}4.19,\;0.97{\sim}1.42%,\;16.2{\sim}22.2\;and\;7,850{\sim}21,000 cp$ respectively. The pH of each product decreased gradually during storage time and reached around pH 4.1 after 16 days with proportional acidity increasing. The viscosity of all test products showed increasing trend by lactic acid bacterial action. Total lactic acid bacteria were $10^8{\sim}10^9\;CFU/ml$ at the beginning storage and increased or decreased depending upon each product. But all product maintained over than $10^8 CFU/ml$ which meets regulatory level after 16 days storage.

• The Korean Journal of Food And Nutrition
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• v.18 no.3
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• pp.200-206
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• 2005

This study was performed to develop a functional stirred yoghurt prepared from skim milk added with loquat(Eriobotrya japonica Lindley). Skim milk containing $15\%$ loquat extract was fermented by the mixed strains of Streptococcus thermophilus and Lactobacillus acidophilus, and then loquat flesh and oligosaccharide were added to the yoghurt base. Sensory scores of the stirred yoghurt containing $15\%$ loquat flesh and $20\%$ oligosaccharide were higher than other groups in sweet taste, sour taste and overall acceptability. When the levels of oligosaccharide of the stirred yoghurts added with $15\%$ loquat flesh were increased, the L value(brightness) and a value (redness) of the stirred yoghurt decreased, but the b value(yellowness) increased. The hardness, springiness, cohesiveness, gumminess and resilience of the $15\%$ loquat flesh stirred yoghurt added with $20\%$ oligosaccharide were higher than others.

• Food Science of Animal Resources
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• v.23 no.4
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• pp.333-341
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• 2003

The effect of water extract of Schizandra chinensis on the growth of yoghurt starter was investigated in order to manufacture the drink type yoghurt added with water extract of Schizandra chinensis. It was the most desirable extraction conditions for Schizandra chinensis to soak in 50 times of water for 15 hours at 20$^{\circ}C$. The water extract of Schizandra chinensis showed pH 3.07, 2.39％ acidity, 1.10％ total sugars, and 0.15 optical density for color. The water extract of Schizandra chinensis was added to MRS broth medium from 0.1％ to 1.0％ and the medium was fermented by 4 types of lactic acid bacteria such as Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus bulgaricus, and Streptococcus thermophilus. The addition of water extract of Schizandra chinensis inhibited the growth of the lactic acid bacteria. The maximum addition amounts of water extract of Schizandra chinensis was 0.9％ for Lac. acidophilus, 0.8％ for Lac. casei, 0.2％ for Lac. bulgaricus and 0.1％ for Str. thermophilus in order to maintain the propagation of the lactic acid bacteria. When the drink type yoghurts added with 0.4％, 0.6％, 0.8％ and 1.0％ water extract of Schizandra chinensis were kept at 4$^{\circ}C$ for 15 days, it was showed that the number of lactic acid bacteria was not significantly changed during the storage. The viable cell counts of the drink type yoghurts by addition of 0.4∼l.0％ of water extract of Schizandra chinensis were 1.13${\times}$10$\^$9/∼2.29${\times}$10$\^$9/ CFU/mL, and these bacterial counts were still more than the legal standard(1.0${\times}$10$\^$8/ CFU/mL) even at 15 days of storage.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.795-799
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• 1989

This study was carried out to hydrolyze lactose in commercial milk by ${\beta}-galactosidase$ from Kluyveromyces fragilis and to compare some physicochemical properties of yoghurts made from control and lactase-treated commercial milks. Quantitative analysis of sugars was performed by gas liquid chromatograph (GLC) on trimethylsilyl (TMS) derivatives. In commercial milk, 94.6% of lactose was hydrolyzed after 2 hours incubation at $40^{\circ}C$ with 6.0 units/ml of ${\beta}-galactosidase$. pH, titratable acidity and viable cell number of yoghurt made from lactase-hydrolyzed (LH) commercial milk were 4.1, 1.04% and $6.5{\times}10^8/ml$ of Str. thermophilus, $8.9{\times}10^8/ml$ of L. bulgaricus after 8 hours incubation at $40^{\circ}C$, respectively, The total contents of amino acid were 2.63% in control and 2.19%. in LH yoghurt. The total contents of free amino acid were 26.95 mg% in control and 17.55mg% in LH yoghurt. Analysis of free fatty acids resulted in that the contents of short chain fatty acids in LH yoghurt were a little higher than those in control. Both in control and LH yoghurt, the palmitic acid content was highest and that was followed by oleic and myristic acid.

• Food Science and Preservation
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• v.20 no.2
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• pp.199-206
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• 2013

To evaluate peanut sprouts as a functional food material, the quality characteristics and antioxidant activities of soybean yoghurt with different percentages (0.5, 1.0, 2.0, and 3.0%) of peanut sprout powder (PSP) contents were investigated. The pH of soybean yogurt with PSP decreased in a time- and dose-dependent manner during fermentation, whereas the titratable acidity increased under the same conditions. The Hunter L value (lightness) decreased while the b value (yellowness) and a value (redness) increased as the PSP concentration in soybean yogurt increased. Prior to fermentation, the sugar content of the soybean yogurt increased as the PSP level increased, but the contents decreased as fermentation progressed. Meanwhile, the viscosity of the soybean yogurt increased during fermentation, and the lactic acid bacteria population was higher than that of the control. The sensory properties, including the flavor, color, taste, and overall acceptability, of the soybean yogurt containing 0.5 and 1% PSP, respectively, were higher than those of other tested yoghurts (with 0, 2.0, and 3.0% PSP contents). The antioxidant activity of the soybean yogurt significantly increased at the PSP concentrations of over 1.0%. These results suggest that the addition of PSP has beneficial effects on the quality and functionality of soybean yogurt, and that the addition of 1.0% PSP is the most suitable for manufacturing soybean yogurt.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.226-236
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• 2012

In the present work, the influence of prebiotic fructooligosaccharide (FOS) on adhesion to Caco-2 cells, viability, acid and bile tolerance, antibacterial, antioxidant, enzymatic, and metabolic activities of the probiotic starters Lactobacillus acidophilus GK20 and Lactobacillus paracasei GK74, has been explored. Experiments were conducted with fermented yoghurt over a period of 7 days at $4^{\circ}C$. When compared to control fermentations without prebiotic, the addition of FOS was seen to significantly (p<0.05) increase the viable cell counts of the probiotics, overall viscosity, and concurrently reduce the pH of the fermented yoghurts. Both Escherichia coli ATCC 11229 and Salmonella enteritidis ATCC 13076 were inhibited by the probiotics' antibacterial activities, while the synbiotic yoghurt containing mixed probiotics and FOS was noted to highly improve antagonistic action. When fermented with mixed starters, the addition of FOS (1.0%) resulted in the highest proteolytic ($1.06{\pm}0.06$ unit) and ${\beta}$-galactosidase activities ($20.14{\pm}0.31$ unit). However, FOS did not affect acid and bile tolerance, adhesion to Caco-2 cells or the antioxidant activity of the probiotics, although both L. acidophilus GK20 and L. paracasei GK74 had functionality as probiotic strains. Hence, a significant synbiotic effect was observed in fermented yoghurt after 7 days of storage at $4^{\circ}C$, and as a result, such synbiotic yoghurt can be said to possess synergistic actions which improve the gastrointestinal environment and promote of health.

• Food Science of Animal Resources
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• v.29 no.4
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• pp.437-444
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• 2009

${\gamma}-Aminobutyric$ acid (GABA) producing lactic acid bacteria, Lactobacillus acidophilus RMK567 was cultivated in 50 L of sterilized MRS broth using a fermenter at $40^{\circ}C$ for 24 h. The cell number was increased to $10.04{\pm}0.13$ Log CFU/mL with a growth rate constant (k) of 0.454 generation/h and a generation time (g) of 2.303 h after a lapse of a lag phase (L) of 5.16 h. A total of 487 g of cell paste with 40.5% moisture was harvested with viable cell number of 12.48 Log CFU/g cell paste. The cell pastes after preparation with glycerol, glucose, and polydextrose as cryo-protectants were lyophilized under a vacuum of 84 m torr. A total of 408 g of freeze dried (FD) cell powders were mixed with a commercial strain of Streptococcus thermophilus to prepare of three types FD starter cultures with the viable cell numbers of 12.42 (FDA-GY), 12.60 (FDBGG) and 12.91 (FDC-GP) Log CFU/g. During preservation the FD cultures at -$18^{\circ}C$, the cell viability of the FD starter cultures were rapidly dropped to below 3.24% of the day of storage. No significant difference was found in the cell viabilities among three types of FD starters cultures, but significant difference (p<0.01) was found in storage periods. Yoghurts fermented through FD starter culture of L. acidophilus RMK567 were determined to contain $155.16{\pm}8.53$ ppm, $243.82{\pm}4.27$ ppm, and $198.64{\pm}23.46$ ppm of GABA, respectively. This study shows that GABA production activity of L. acidophilus RMK567 is not affected during the freeze drying process and would be available for commercial production of yoghurt containing high GABA content.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.182-189
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• 1980

This experiment was carried out to study on methods of processing the fruit base which is to be used for preparing the fruit yoghurts. Common fruits were compared and peach was chosen among them for this purpose by determing the rate of decrease in hardness during the process of cooking. The maturity, temperature of cooking and methods of peeling were tested to maintain the desirable hardness during the process, and the effects of metallic ion addition on the hardness of the flesh were also studied. The results obtained were as follows. 1. The peaches were keeping the most stable texture during cooking, among common fruits, however the hardness of apples were decreased markedly. Rate of decreases in the flesh hardness were high during the initial stages of cooking then slowered in all fruits tested. 2. Flesh hardness of the peaches were largely affected by the temperature of cooking. And the texture of freeze-stored fruits was severly damaged during thawing, so that could be used only for the limited purposes such as for stirred-type yoghurt. 3. Divalent matallic ions, especially calcium ion, were effective for supporting the flesh hardness of peaches during cooking. 4. The optimal concentration of calcium chloride addition was 0.3%, and this resulted in its final concentration in the product under the legal dosage without any subsquent changes in colour and flavor. 5. The effects of calcium chloride addition were greater in the froms of dices than in those of slices, and in overmature fleshs than in immature ones. 6. Treatment of calcium chloride by soaking the slices or dices of lye-peeled peaches in 0.3% solution was found to be adaptable for the practical process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.942-947
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• 2003

The effects of anti-stress rose (Rosa mutiflora) fruit extract yoghurts (RFEY-1.0, RFEY-3.0, RFEY-5.0 containing with 1.0, 3.0 and 5.0% of rose fruit extract) were tested for the anti-stress effects. ICR male mice (20$\pm$2 g) were fed with basic experimental diets and given free access to water containing these ingredients for 18 days. Psychological stress and sociopsychological stress exposed by foot-shock for 1 hour (10 sec duration at intervals of 120 sec) every day for 3 days. RFEY-1.0, RFEY-3.0, RFEY-5.0 groups in the sociopsychological stress resulted in a significant decrease of 11.7%, 16.0% and 24.7% in plasma corticosterone (CS) secretion compared with psychological stress (control group). Noradrenaline (NA) secretions in the brain were significantly increased 15.6%, 25.0% and 40.8%, respectively, in RFEY-1.0, RFEY-3.0, RFEY-5.0 groups compared with control group. MHPG -SO$_4$ (3-methoxy-4-hydroxy-phenylethyleneglycol sulfate) levels in the brain resulted in a marked decreases of 17.0%, 25.3% and 28.4%, respectively, in RFEY-1.0, RFEY-3.0, RFEY-5.0 groups compared with control group. NA/MHPG-SO$_4$ ratios in the brain of RFEY-1.0, RFEY-3.0, RFEY-5.0 groups resulted in a significantly increase of 39.5%, 67.3% and 96.3%, respectively, compared with control group. These results suggest that rose fruit extract yoghurt may be tried to apply for human consumption such as sociopsychological stress.