• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1579-1585
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• 2005

The aim of this study was to propose utilization of tofu whey concentrates separated by ultrafiltration (UF) for yogurt production. The curd yogurt was prepared from whole milk added with skim milk Powder in which UF powder was substituted 0$\%$, 6.25$\%$, 12.5$\%$ or 25$\%$ for skim milk powder. The quality characteristics of yogurt in terms of pH, titratable acidity, viscosity, color and viable cell counts were evaluated. There were no significant differences in pH and titratable acidity between control (yogurt added with only skim milk powder) and yogurt added with UF powder after 24 hr of fermentation at 37$^{\circ}C$. Apparent viscosity of yogurt added with UF powder was lower (2,623 $\∼$ 3,189 cps) than that of the control yogurt (3,196 cps). Lightness and redness value of yogurt added with UF powder were not significantly different from control yogurt, while yellowness value increased as the amount of UF powder increased. Addition of UF powder stimulated the growth of lactic acid bacteria. Gas chromatographic analysis detected acetaldehyde, diacetyl, and organic acids, and more volatile compounds were detected in yogurt added with UF powder. Sensory analysis showed that yogurt added with UF powder were evaluated as acceptable as control yogurt. Therefore, UF powder could be substituted for skim milk powder without depressing yogurt qualify.

• Food Quality and Culture
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• v.1 no.1
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• pp.22-26
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• 2007

This study was performed to determine the feasibility of developing a healthy yogurt using tofu whey concentrates separated by nanofiltration (NF). The curd yogurt was prepared from whole milk with added skim milk powder, in which the NF powder was substituted at 0, 6.25, 12.5, or 25% for the skim milk powder. The quality characteristics were evaluated for pH, titratable acidity, viscosity, color, and viable cell counts. There were no significant differences in pH or titratable acidity between the control (yogurt with added skim milk powder only) and the yogurts with added NF powder, after 24 hr of fermentation at $37^{\circ}C$. The apparent viscosities of the yogurts with added NF powder were higher ($3,197{\sim}3,574\;cps$) than that of the control yogurt (3,196 cps). Lightness decreased, while yellowness increased, as the amount of NF powder increased. Sensory evaluations showed that the NF powder could be substituted for the skim milk powder at 6.25% without lowering the yogurt quality.

• Food Science of Animal Resources
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• v.31 no.1
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• pp.66-73
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• 2011

Physicochemical and sensory properties of Dioscorea opposita Thunb. (yam) powder-added yogurts (1, 3, 5, and 7%, w/v) were examined when stored at $4^{\circ}C$ for 16 d. When the yam concentration increased, the pH increased with 16 d storage. The lactic acid bacteria counts in all yogurt samples showed an increase during storage period, and the highest counts were appeared with 7% yam powder addition. The dramatic decrease was found in viscosity with higher concentrations of yam powder-added yogurt samples. No change was found in allantoin and diosgenin contents for 16 d storage periods. A significantly strong bitterness and astringency and decreased viscosity were found with 5 and 7% yam powder addition. However, less than 3% yam powder-added yogurt samples did not show a significant difference compared with the control (p>0.05) and overall acceptability score was the highest in 3% yam powder-added yogurt throughout the storage. The present study indicated that the concentrations (1 and 3%, w/v) of yam powder could be used to produce yam powder-added yogurt without significant adverse effects on physicochemical, microbial and sensory properties, and enhance functional components from the supplementation.

• The Korean Journal of Food And Nutrition
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• v.13 no.1
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• pp.71-77
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• 2000

New type yogurt base were prepared from milk added with skim milk powder or purple sweet potato, and fermented by lactic acid bacteria (Streptococcus thermophilus and Bifidobacterium infantis, 1:1, v/v). The yogurt proudcts were evaluated for acid production(pH, titratiable acidity), number of viable cell, viscosity, sensory properties, and color value. The composition of some organic acids was also analyzed by GC. The acid production slightly decrerased by addition with purple sweet potato. There was no significant difference in viable cell counts between control (yogurt added with only skim milk powder) and yogurt added with purple sweet potato, and viable cell counts of all samples were above 9.08 log cfu/ml. Viscosity of yogurt added with purple sweet potato(36,800∼46,000 centipoise) was higher than that of yogurt added with only skim milk powder(32,200 centipoise). The overall sensory score of yogurt added with purple sweet potato(38.6%, dry base) was the best of tested yogurt. The major organic acid of yogurt added with purple sweet potato was lactic acid. its content was 0.997∼1.203%. malic acid, succinic acid, oxalic acid, and fumaric acid were analyzed out a little. Lightness and yellowness decreased by addition with purple sweet potato but redness increased. Total color difference($\Delta$E) with yogurt addition with purple sweet potato and only skim milk powder were very high(above 11.46).

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

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.254-260
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• 1995

Yogurt base were prepared from milk added with skim milk powder or Aloe vera powder and femented with lactic acid bacteria(the single or mixed strain of Lactobacillus bulgaricus and Streptococcus thermophilus). The yogurt product were evaluated for acid production(pH, titratable acidity), number of viable cell, viscosity, sensory property and quality-keeping property. The composition of organic acid were also analyzed by HPLC. Addition of Aloe vera remarkably accelerated acid production, and titratable acidity of Aloe vera yogurts(1.293∼1.407%) after 24 hours incubation was higher than that of yogurts added with only skim milk powder(9.98∼1.110%). Yogurt fermented with the mixed strain of L. bulgaricus and Sc. thermophilus was more acidic than that of single strains. The propagation of lactic acid bacteria was stimulated by Aloe vera and the number of viable cell after 24 hours incubation were above 9.87log CFU/ml. Viscosity of Aloe vera yogurt(3,860∼4,300CPS) was higher than that of yogurt with only skim milk powder(2,402∼2,604CPS). The overall sensory score of Aloe vera yogurt femented by mixed strain was the best of tested yogurt. When yogurt with Aloe vera was kept at 5℃ for 15 day, it's quality-keeping property was relatively good. The major organic acid of Aloe vera yogurt was lactic acid and lactic acid content of yogurt increased by addition of Aloe vera powder. The citric acid content decreased wtih fermentation and malonic acid, pyroglutaric acid and α-ketoglutaric acid were analyzed out a little.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.48-52
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• 2007

Yogurt base was prepared from skim milk supplemented with 0.2-1.0% (w/v) garlic powder and fermented with lactic acid bacteria (the mixed strain of Lactobacillus acidophilus, Bifidobacterium longum and Streptococcus thermophilus) at 40$^{\circ}C$ for 18 h. Quality characteristics of the prepared yogurt were evaluated for acid production (pH and titratable acidity), number of viable cells, viscosity and sensory properties. The addition of garlic powder inhibited the growth of lactic acid bacteria and decreased the acid production. After 18 h incubation, titratable acidity of garlic yogurt was 1.28-1.08% and was lower than that (1.35%) of yogurt made with only skim milk. However, the viscosity of yogurt was remarkably increased by the addition of garlic powder. The sensory score of yogurt added with 0.2% garlic powder was similar to ordinary yogurt in flavor and overall acceptability. According to sensory score and fermentation characteristics, the optimum concentration of garlic powder was around 0.2%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1128-1134
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• 1997

Lactobacillus helveticus was inoculated to the fermentation liquid containing skin milk powder(SMT) plus soymilk, SMP plus isolated soybean protein(ISP), SMP plus ISP plus whey powder(WP) to increase the nutritional and economic value of commercial soy yogurt. The yogurt fermented with soymilk and SMP showed the lower acid production than of SMP and had significant beany flavor in the product. The yogurt prepared with ISP and SMP showed the higher cell number and lower acid production than that of SMP. Also, the partial substitution of SMP with ISP over 6%(w/w) produced less acceptable product due to gel production. The yogurt prepared by the partial substitution of SMP with ISP, WP and SMP showed the higher cell number and lower acid production than that of SMP and not bring about gel formation unlike the case of ISP. Sensory properties of yogurt substituted SMP with ISP and WP(38:62 mixture) below 4% were not significantly different from that of SMP and the sample containing the mixture over 6% and 0.067% artificial flavor showed lower sensory score due to beany taste than that of SMP. But increase of yogurt flavor up to 0.1% resulted in significantly high score in organoleptic acceptability. The separation of water occured in yogurt prepared by the combined mixture of ISP, WP and SMP, and this problem could be resolved by addition of Na-alginate and PGA at the concentration of 0.1%(w/w).

• Food Science and Preservation
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• v.10 no.2
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• pp.175-181
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• 2003

Yogurt base was prepared from skim milk supplemented with sweet persimmon powder at the levels of 4% and 7％ and was fermented with Lactobacillus acidophillus. Sweet persimmon powder contained protein 2.2%, fat 30.5%, carbohydrate 56.6% and ash 2.5%, Quality characteristics of prepared yogurt were evaluated for acid production(pH), visible cell numbers, sensory property and oganic acid compositions during fermentation. Lactic acid content in yogurt supplemented with sweet persimmon powder was higher (1.12%∼l.21%) than that (1.05%) in yogurt made with only skim milk after 24 hours fermentation. The sensory score was higher yogurt made with skim milk than yogurt supplemented with sweet persimmon powder in taste, texture and overall acceptability. However, the acid production in yogurt supplemented with sweet persimmon powder were not significantly difference compared to yogurt made with skim milk The antioxidative activity by DPPH(a-a'-diphenyl-${\beta}$-picrylhydratyl) method in yogurt supplemented with sweet persimmon powder and yogurt made with skim milk were higher than BHT 0.005 ％ used as control.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.5
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• pp.690-697
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• 2014

This study was conducted to investigate the effect of mulberry powder on the antioxidant activities and quality characteristics of yogurt. The samples were fermented with different amounts (0, 0.5, 1, and 3% to the yogurt quantity) of mulberry powder for 24 hr. The total phenol content, anthocyanin content, and DPPH radical scavenging activity of yogurt significantly increased with higher mulberry powder content. The pH decreased with higher mulberry powder content until 16 hr, whereas the treated groups showed higher pH levels than the control group after 20 hr. Acidities of the treated groups were higher than that of the control group upon addition of mulberry powder. Citric acid, succinic acid, and lactic acid contents of the treatment group were higher than that of the control until 16 hr, whereas the free organic acid content of the control group increased after 20 hr. The amount of lactic acid bacteria increased with higher mulberry powder content until 12 hr, whereas that of the treated group tended to decrease compared to the control group after 16 hr. Color values of mulberry yogurt were lower in terms of brightness and yellowness, whereas redness value was higher compared to the control. Mulberry yogurt groups showed higher sensory attributes than the control, except for 3% added yogurt. Consumer acceptability score of yogurt with 1% mulberry powder was ranked higher than those of other yogurts in terms of overall preference, sourness, color, flavor, and sweetness. We suggest that mulberry powder can be used to improve the quality characteristics, functionality, fermentation, and sensory evaluation of yogurt.