• Korean Journal of Food Science and Technology
• /
• v.25 no.2
• /
• pp.136-141
• /
• 1993

A curd yogurt was prepared from milk added with skim milk powder or four kinds of cereal. The effect of cereals at 2%(w/v) level on the pattern of volatile aroma compounds in curd yogurt was investigated. Acetaldehyde, acetone, ethanol, diacetyl, butanol and acetoin in curd yogurt were detected by gas chromatographic analysis. Among these compounds, acetaldehyde, ethanol, diacetyl and acetoin were produced during fermentation by Lactobacillus acidophilus (KCTC 2182). The addition of cereals did not affect markedly general pattern of volatile aroma compounds in curd yogurt. The amount of acetoin and ethanol markedly increased until the first 6 hours of fermentation, and then increased mildly until 24 hours. The amount of diacetyl markedly increased until the first 6 hours and then decreased slightly. Acetaldehyde was first detected by gas chromatograph after 18 hours of fermentation.

• Journal of Applied Biological Chemistry
• /
• v.59 no.4
• /
• pp.345-349
• /
• 2016

This study was performed to evaluate the quality characteristics of curd yogurt with different contents [0.5~2.0% (w/w)] of Korean rice wine lees powder (KRWLP). Yogurt was fermented with commercially available mixed lactic acid bacteria (Lactobacillus acidophilus, Bifidobacterium longum, Streptococcus thermophiles) at $40^{\circ}C$ for 15 h. Acid production (pH and titratable acidity) of yogurts increased with increasing KRWLP content. After 12 hours fermentation, titratable acidity of KRWLP yogurt was 1.19~1.29 % and was higher than that (1.07 %) of yogurt made without KRWLP. And also, the number of viable lactic acid bacterial cell increased and the culture time to obtain maximum number of lactic acid bacteria cell decreased with the addition of KRWLP. The curd stability in yogurt was significantly enhanced by repression of whey separation in KRWLP yogurt. In sensory evaluation, there was a similar preference for KRWLP yogurts and the control. These results suggest that KRWLP can be used as foodstuff to improve the quality characteristics of yogurt.

• Korean Journal of Medicinal Crop Science
• /
• v.6 no.4
• /
• pp.265-270
• /
• 1998

The curd yogurt was prepared from skim milk powder added with the juice, puree and powder, respectively, of the roots of Platycodon grandiflorum (Jacq.) A.DC. Twelve hours were proved to be best for fermentation of the curd yogurt, which showed 4.1 in pH and 1.15% in titratable acidity. Quality of the curd yogurt in sensory evaluation was best when 2 % of juice, 1 % of puree and 1 % of powder were added to the skim milk powder, respectively. When curd yogurt was kept at $5^{\circ}C$ for 9 days, pH decreased, while titratable acidity increased. The viscosity was highest with addition of puree 1%. After fermentation, number of viable cell was $6.2{\times}10^8/ml$ in control. $4.4{\times}10^8/ml$ in juice 2%, $3.7{\times}10^8/ml$ in puree 1% and $4.2{\times}10^8/ml$ in powder 1%. When curd yogurt was kept at $5^{\circ}C$ for 9 days, its keeping quality (pH, titratable acidity, viscosity and number of viable cells) were good.

• Journal of Food Hygiene and Safety
• /
• v.14 no.4
• /
• pp.352-357
• /
• 1999

Changes in titratable acidity, viable cells and sensory properties of curd yogurt during lactic fermentation in milk added with mugwort extract have been studied. Milk added with 5%, 10％, 15％ or 20% of mugwort extract was fermented with single or mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus for 24 hours. Addition of mugwort extract markedly stimulated the acid production and propagation of lactic acid bacteria. Among the organism tested, the mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus produced the highest amount of acid, and Lactobacillus bulgaricus showed the highest number of viable cell counts. Sensory property of curd yogurt added with mugwort extract was evaluated as better than reference sample(milk yogurt). The sample prepared by fermenting milk containing mugwort extract at 5% level with Lactobacillus bulgaricus showed the most favorite characteristics.

• Food Science and Preservation
• /
• v.6 no.4
• /
• pp.442-447
• /
• 1999

A curd yogurt was prepared by fermenting milk added with skim milk powder and purple sweet potato by culture of 5 types of lactic acid bacteria(Lactobacillus delbruekii sub. sp. lactis, Streptococcus lactis, acidity, number of viable cell, stability of purple sweet potato's pigment and keeping qualify. Among the organisms tested, the acid production and number of viable cell by the culture of L bulgaricus remarkably increased for the first 12 hem which showed 1.04${\times}$10$\^$9/ CFU/mL in number of viable cell and 4.22 In pH where as fermentation by the culture of B. bifidum was slow. After 36 hours of incubation which showed 3.3 ${\times}$ l0$\^$8/ CFU/mL in number of viable cell and 5.1 in pH. In stabilities of purple sweet potato anthocyanin pigment n fermentation, yogurt by B. bifidum was found to be most stable followed by Leuc. lactis, L. delbruekii sub. sp. lactis, L bulgaricus, but yogurt by St. lactis was not stable. When curd yogurt added with Purple sweet Potato was kept at 2∼3$^{\circ}C$ for 14 day, its keeping quality(pH, titratable acidity, number of viable cell) was relative good except product by L. bulgaricus was found to be decreased most of viable cell. After 2 weeks of keeping, pigment of yogurt was decreased by B. bifidum, stable by L. delbruekii sub. sp. lactis.

• Korean Journal of Food Science and Technology
• /
• v.27 no.1
• /
• pp.47-55
• /
• 1995

New type yogurts were prepared by fermenting whole milk containing soy milk and/or brown rice with single or mixed culture of 4 types of lactic acid bacteria(Lactobacillus acidophilus, Lactobacillus bulgaricus, Leuconostoc mesenteroides, Streptococcus thermophilus). The curd yogurts were evaluated by acid production (pH, titratable acidity), number of viable cell, keeping quality and sensory property. Addition of soy milk and brown rice markedly stimulated the acid production and propagation of lactic acid bacteria, and slightly increased the Brix degree. Among the organisms tested, the mixed culture of Leuconostoc mesenteroides and Streptococcus thermophilus produced the highest amount of acid, and that of Leuconostoc mesenteroides and lactobacillus acidophilus showed the highest number of viable cell counts. When curd yogurt added with soy milk and brown rice was kept at $3^{\circ}C$ for 15 days, its keeping quality was relatively good. The sensory evaluation showed that the curd yogurt containing soy milk and brown rice slightly reduced the texture property and overall acceptability comparing with milk yogurt.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.1
• /
• pp.69-77
• /
• 2013

Jujube is a functional food, containing medicinal ingredients without side effects. Jujube can relieve digestive upset, inhibit tumor growth and protect the liver. It includes sterols, alkaloids, saponins, vitamins, organic acids, and amino acids. Jujube has also received attention as an anticancer agent and as a diet food. However, it is rare to find yogurt made with jujube, so we considered adding jujube powder to yogurt to popularize it as a new health food. We made yogurt with jujube powder at 0, 1, 2, 3, and 4%. We measured pH, acidity, color properties (brightness, redness, yellowness), viscosity, sensory qualities (color, flavor, taste, overall quality). We also experimented with storage stability at intervals of 1, 5, 10, 15, and 20 days. The results showed that pH increased significantly (p<0.001) with increasing amounts of added jujube powder. The pH also rose significantly with longer storage, but tended to decrease after 20 days. Acidity was reduced during the storage period. Viscosity was highest with 1% added jujube powder (p<0.001) on day 5 of storage (p<0.001). The L color value decreased as the amount of added jujube powder increased, whereas the a-value (redness) and b-value (yellowness) increased (p<0.001). In an sensory test, color in samples with 0, 1, and 2% jujube powder exhibited the highest values (p<0.01), but no significant differences in flavor or texture were observed. Sweetness and sourness were highest in the yogurt with 3% jujube powder (p<0.05). Overall quality tended to be higher for yogurt with 3% jujube powder, but the difference was in significant. Taken together, our results indicate that yogurt with 3% jujube powder may the most suitable for manufacturing purposes.

• Korean Journal of Food Science and Technology
• /
• v.49 no.6
• /
• pp.625-631
• /
• 2017

This study was performed to examine the quality characteristics and antioxidant activity of curd yogurt with varying content (0.5-2% (w/w)) of lemon grass hot-water extract (LGHWE). The pH decreased with higher LGHWE content until 8 h, with the treated groups showing higher pH values than the control group after 12 h. The viscosity and the viable cell counts of the yogurt with 2% LGHWE were significantly lower than those of the control group during fermentation. Color values of LGHWE yogurt were lower in terms of brightness, whereas redness and yellowness values were higher compared to the control. The DPPH radical scavenging activity and soluble content significantly increased with higher LGHWE content. Consumer acceptability score of yogurt with 0.5% LGHWE was ranked higher than that of other yogurts. Yogurt containing 0.5% LGHWE showed no differences in pH and titratable acidity compared to control after storage at $4^{\circ}C$ for 14 days.

• The Korean Journal of Food And Nutrition
• /
• v.16 no.1
• /
• pp.66-71
• /
• 2003

For the purpose of making a functional and stable yogurt, new type yogurt were prepared from 12% whole milk and 2% skim milk added hot-water extracted from sea tangle. The yogurt product were evaluated for acid production(pH, titratable acidity), number of viable cell, viscosity, degree of curd sedimentation, quality-keeping property and sensory property. By addition of hot-water extracted from 0.5% sea tangle, the titratable acidity of yogurt(1.89%) was higher than that of yogurt not added hot-water extract of sea tangle(1.53%). The propagation of lactic acid bacteria was stimulated by adding hot-water extracted from 0.5% sea tangle, and the number of viable cells were about 1.4${\times}$10$\^$9/CFU/$m\ell$. On the other hand, the number of viable cells in control were 4.4${\times}$10$\^$8/CFU/$m\ell$. Viscosity of yogurt made from adding hot-water extracted from 0.5% sea tangle(25 CPS) was higher than that of yogurt with only milk(22 CPS). When yogurt made from adding hot-water extracted from sea tangle was kept at 7$^{\circ}C$ for 15 days, its quality-keeping was relatively good. The sedimentation of curd was repressed a little by adding hot-water extracted from 0.5% and 0.1% sea tangle. The overall sensory score of yogurt made from adding hot-water extracted from 1% sea tangle was the best of tested yogurt.

• The Korean Journal of Food And Nutrition
• /
• v.21 no.2
• /
• pp.135-142
• /
• 2008

This study investigated to develop new functional yogurt added domestic yuza(Citrus junos). In order to make the most effective yogurt, yuza extract and fructose were mixed at different proportions. DPPH free radical scavenging activity of yuza yogurts increased dependent on concentration. The results of the DPPH free radical scavenging activity, the 1% yuza yogurt was proven to be the best. The overall sensory score for yogurt made from adding 1% yuza ethanol extract was the best of tested yogurts. The antioxidant activity(DPPH free radical scavenging activity) was the highest in 1% yuza yogurt. The quality characteristics of prepared yogurt were evaluated in terms of acid production(pH and titratable acidity), viscosity, color and levels of lactic acid bacteria during storage period. During storage, the quality of yogurt made from adding yuza extract was better than control(without yuza extract). The sedimentation of curd was repressed a little by adding 1% yuza extract.