• Korean Journal of Food Science and Technology
• /
• v.46 no.5
• /
• pp.556-565
• /
• 2014

In this study, we evaluated changes in physicochemical properties, total phenol and isoflavone contents, and antioxidant activity during soymilk fermentation by a potential probiotic Lactobacillus plantarum P1201. The P1201 strain showed survival rates of 58.14% and 62.22% after 4 h exposure to acid and artificial gastric acid conditions (pH 2.5), respectively. The optimal conditions for soy-yogurt fermentation by L. plantarum were determined to be as follows: temperature of $35^{\circ}C$, seed volume of 5.0%, and sucrose content of 10.0%. The total phenol and isoflavone contents and antioxidant activity were higher in soy-powder milk (SPM) yogurt than soymilk yogurt. In particular, the highest levels of isoflavone-aglycones, such as daidzein, glycitein, and genistein (91.50, 12.34, and $61.39{\mu}g/g$, respectively), were observed after 48 h of SPM fermentation. Thus, these results suggest that the soy-yogurt extract could be used as a potential source of natural antioxidants in food.

• The Korean Journal of Food And Nutrition
• /
• v.26 no.2
• /
• pp.280-286
• /
• 2013

This study was performed to investigate the effect of types of microorganisms on the antioxidant activity of soybean yogurt by a single or mixed culture of Bacillus subtilis and Lactobacillus plantarum isolated from chunggukjang and kimchi. The fermented soybean milk by Bacillus subtilis exhibited the highest values of total polyphenol, DPPH radical scavenging activity, reducing power and nitrite scavenging activity compared to those of Lactobacillus plantarum or mixed culture of Bacillus subtilis/Lactobacillus plantarum. As the amount of tomato extract was added to the soybean milk, various antioxidant parameters, such as total polyphenol, DPPH radical scavenging activity, reducing power and nitrite scavenging activity, were linearly increased.

• Korean Journal of Food Science and Technology
• /
• v.47 no.6
• /
• pp.765-771
• /
• 2015

This study was performed to examine the quality characteristics and antioxidant activity of the curd yogurt with different contents (0.5-2%, w/w) of acanthopanax powder (AP). The pH decreased with increasing AP content until 16 h, whereas the treated groups showed higher pH levels than the control group after 20 h. The viscosity and the viable cell counts of the yogurt with 2% AP were lower than those of the control group during fermentation, significantly. Color values of AP yogurt were lower in terms of brightness, whereas redness and yellowness values were higher compared to the control group. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and soluble content significantly increased with increasing AP content. Consumer acceptability score of yogurt with 0.5% AP was ranked higher than other yogurts. Yogurt added with 0.5% AP showed no differences in pH, titrable acidity, and viable cell counts compared to the control group after storage at $4^{\circ}C$ for 14 days.

• Journal of Applied Biological Chemistry
• /
• v.58 no.4
• /
• pp.311-316
• /
• 2015

Yogurt was prepared with different substitution ratio [10, 30, and 50% (w/w)] of skim milk with enzymatically hydrolyzed purple sweet potato powder (EHPSPP) and fermented at $40^{\circ}C$ for 15 h. Fermentation characteristics and antioxidant activities of the yogurt were evaluated in terms of acid production (pH and titratable acidity) and lactic acid bacterial counts and DPPH radical scavenging activity, respectively. After 15 h fermentation, titratable acidity of EHPSPP yogurt was 0.80-0.89% and was lower than that (0.93%) of yogurt made without EHPSPP. The acid production and the number of viable lactic acid bacterial cell decreased with increasing the substitution ratio. The sensory score of EHPSPP yogurt prepared with 30% substitution ratio showed the highest values in taste and overall acceptability among the tested yogurt preparations. DPPH radical scavenging activity increased with increasing the substitution ratio in yogurt fermented for 12 h. The total phenolic content of 30% EHPSPP yogurt was 40% higher than that of skim milk yogurt. These results suggest that EHPSPP can be used as substituent of skim milk and the optimum substitution ratio is around 30%.

• Korean Journal of Food Science and Technology
• /
• v.51 no.3
• /
• pp.200-206
• /
• 2019

A potentially functional yogurt co-fermented with Monascus-fermented soybean powder (MFSP) was prepared, and its quality and antioxidant properties were investigated. Skim milk powder with (SMP+MFSP, 1:1, w/w) or without MFSP (SMP; control) was fermented by probiotic cultures consisting of L. delbrueckii subsp. bulgaricus KCTC 3635 and S. thermophilus KCTC 5092. The functional yogurt fermented with MFSP contained significantly (p<0.05) higher levels of ${\gamma}-aminobutryric$ acid (GABA; $107.22{\pm}3.06{\mu}g/g$), isoflavone aglycone (daidzein+genistein; $201.21{\pm}6.29{\mu}g/g$), and ubiquinone ($39.05{\pm}0.08{\mu}g/g$) than the control yogurt. During fermentation at $36^{\circ}C$ for 48 h, the functional yogurt displayed higher titratable acidity, viable cell numbers, and radical scavenging activity and a lower pH than the control yogurt (p<0.05). These results indicate that MFSP has great potential for enriching the free isoflavones, GABA, and ubiquinone contents in yogurt.

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

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.9
• /
• pp.1229-1236
• /
• 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 Dairy Science and Biotechnology
• /
• v.37 no.4
• /
• pp.237-246
• /
• 2019

In this study, quality characteristics of yogurt supplemented with Angelica gigas Nakai leaf extract were examined. The pH of the yogurt ranged from 4.40 to 4.45 and the titratable acidity ranged from 0.96% to 0.98%. The viscosity tended to decrease with the addition of the Angelica gigas Nakai leaf extract, but did not affect stability during storage. In the range of 0.1% to 0.3%, lactic acid bacteria were present in the range of 1.9×10⁹ to 3.2×10⁹ CFU/mL. The decursin content in yogurt was quantitatively analyzed, depending on the addition of 0.1% to 0.3% of Angelica gigas Nakai leaf extract and was found to be 0.26 ㎍/g, 15.23 ㎍/g, and 23.57 ㎍/g respectively. Organic acid showed the highest generation of lactic acid. The antioxidant properties of yogurt were shown to increase with the addition of the Angelica gigas Nakai leaf extract. The sensory score of yogurt supplemented with 0.1% of the Angelica gigas Nakai leaf extract was highly valued, at a level similar to that of plain yogurt. Yogurt supplemented with 0.2% of the extract was rated above the normal score of 6.31 to 6.50. As shown by the results, the optimal concentration of Angelica gigas Nakai leaf extract for addition to yogurt was within 0.2%.

• Korean Journal of Food Science and Technology
• /
• v.45 no.6
• /
• pp.721-726
• /
• 2013

In this study, a yogurt containing skim milk powder and whole barley flour was fermented with lactic acid bacteria, and its quality and properties were estimated. The yogurts with 1% and 3% barley flour had lower pH values, higher titratable acidity, and higher Brix values than the control. In addition, the viable cell counts were lower and viscosity was higher. The value of L was low, and the values of a and b were high. The yogurt with 3% barley flour had more lactic acid than the control and showed a substantial increase in the amount of acetic acid. ${\beta}$-Glucan content and antioxidant activity increased with the amount of barley flour added. In sensory evaluation, there was a similar preference for the yogurt with 3% barley flour and the control, and as the barley flour content increased, the preference decreased. Moreover, the preference for the yogurt was higher among old people.

• Korean Journal of Microbiology
• /
• v.50 no.1
• /
• pp.8-14
• /
• 2014

The objective of this work is to investigate and compare several functional properties of lactic acid bacteria (LAB), Lactobacillus casei SK-7 isolated from home-made yogurt and Lactobacillus bulgaricus YK-11 from commercial yogurt. Initially, physiological and biochemical properties of SK-7 and YK-11 were characterized. Phylogenetic analysis using 16S rRNA sequencing were performed to identify the strains, and the strain could be assigned to Lactobacillus casei and Lactobacillus bulgaricus, designated as L. casei SK-7 and L. bulgaricus YK-11. Phylogenetic tree of SK-7 and YK-11 was plotted based on 16S rRNA sequence comparisons. Production of lactic acid and organic acid, and pH changes in the cultures of SK-7 and YK-11 were monitored during 72 h. During the incubation period, several functional properties of L. casei SK-7 and L. bulgaricus YK-11 were examined. L. casei SK-7 and L. bulgaricus YK-11 cultures eliminated 93.9% and 88.2% of nitrite, respectively. Antioxidant activity of cultural supernatants of SK-7 and YK-11 were 62.6%, 54.9%, and activity of ${\beta}$-galactosidase were 14.9 units/mg and 13.1 units/mg, respectively. The antimicrobial activities were examined with 20-fold concentrated culture supernatants from the cultures of SK-7 and YK-11. The activities of SK-7 supernatants were clearly observed against all microorganisms in this work, whereas no activities were observed in YK-11 supernatants. Although it might be conducted additional functional research, functional properties of LAB isolated from home-made yogurt have been shown to be better than those of commercial yogurt in this work.