• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.358-366
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• 2013

The aim of this study was to evaluate the antimicrobial activities of Glycyrrhiza uralensis and Glycyrrhiza glabra extracts with various countries of origin. Three samples of licorice with various origins (Korea, China, and Uzbekistan) were evaluated for their antimicrobial activities against six skin microflora. The bioassay applied for determining the antimicrobial effects included the disc diffusion assay, minimum inhibitory concentration, and challenge test. The ethyl acetate fractions of G. uralensis and G. glabra extracts showed significant antimicrobial activities against two gram-positive (Bacillus subtilis, Propionibacterium acnes) and two gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. These samples had much more intensive antimicrobial activities than synthetic preservatives on B. subtilis, P. acnes, and P. aeruginosa, especially. Korean licorice showed the highest antimicrobial activity amongst the samples tested. In view of the observed inhibitory features of these G. uralensis and G. glabra extracts, it is suggested that they could be used as natural antiseptics against bacterial contamination in cosmetics and foods, instead of the common synthetic preservatives currently employed.

• Food Science and Preservation
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• v.17 no.1
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• pp.160-164
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• 2010

Chemical methods using browning inhibitors have been used to control the browning of chopped garlic. However, consumer demand for natural products is increasing, and we therefore investigated the antibrowning effect of natural licorice root extract on chopped garlic. We used a combination of licorice extract and citric acid. Chopped garlic was exposed to citric acid and licorice extract at various levels and L values were measured during storage at $10^{\circ}C$. Licorice extract was effective as an initial antibrowning, and a mixture of licorice extract and citric acid was effective in inhibition of browning during storage. The effective mixing ratio of licorice extract and citric acid was 5:5 and 2:8. This indicates that licorice extract and citric acid synergistically act to inhibit browning of chopped garlic. Licorice extracts with higher levels of glycyrrhizin were more effective as antibrowning agents for chopped garlic.

• Korean Journal of Food Science and Technology
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• v.53 no.4
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• pp.479-485
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• 2021

To improve the oxidative stability of Glycyrrhiza uralensis extract (GU), GU extraction conditions were optimized for maximal antioxidant activity, and GU-loaded nanocapsules were prepared by chitosan ionic gelation. The optimized ethanol concentration and extraction time were 83.0% and 32.6 min, respectively, using response surface methodology. The particle size of the GU-loaded nanocapsules ranged from 280 to 370 nm. A GU extract of 0.8 mg/mL and chitosan concentration of 2.0 mg/mL were selected as the optimal conditions for entrapment and loading efficiency. Both free GU and GU-loaded chitosan nanocapsules exhibited concentration-dependent antioxidant activity. However, the antioxidant protection factor of GU was effectively maintained when it was entrapped within the chitosan nanocapsules. In conclusion, chitosan nanoencapsulation is a potentially valuable technique for improving the oxidative stability of GU.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1221-1225
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• 2003

As an effort to select powerful anti-cariogenic materials from natural resources, various plant extracts were examined for their anti-S. mutans and anti-glucosyltransferase (GTase) activities. The ethanol extracts of licorice bark, which was produced after water extraction of licorice, showed the most powerful anti-S. mutans as well as anti-GTase activities. When licorice bark was consecutively fractionated with n-hexane, chloroform, ethylacetate, and butanol, the chloroform fraction exhibited the strongest anti-S. mutans activites. This fraction was further fractionated into 4 fractions through a silica gel column, and according to HPLC analysis, anti-S. mutant activities seemed to come mostly from relatively hydrophobic materials.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.159.1-159
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• 2003

표준화된 청국장 제조법으로 대두를 정선, 수세 후 3배의 물을 가하여 24시간 침지하고 물빼기를 한 후 121$^{\circ}C$에서 1시간 동안 증자한 후 4$0^{\circ}C$까지 냉각한 후 재래청국장으로부터 분리한 B. lichenifomis 균주를 2% 접종, 4$0^{\circ}C$에서 54시간 발효시켜 청국장을 제조하였으며 발효 방법에 따라서는 종균을 접종한 경우가 가장 우수한 발효양상을 보였다. 감초추출물을 첨가하여 제조한 청국장의 품질특성을 알아본 결과 첨가농도가 증가할수록 pH가 증가하였으며 환원당 함량도 증가하였다. 색도는 첨가농도가 증가함에 따라 다소 어두워 졌으나 점질물의 생성량은 증가하는 경향이었다. 관능검사결과를 종합해 보면 5%의 첨가구에서 가장 높은 기호도를 보여 증자 대두에 감초추출물을 혼합하여 발효했을 경우 점질물의 생성의 증대는 물론 기호도의 향상에도 크게 기여하였다.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.194-200
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• 2008

This study was performed to examine the properties of takju containing added Glycyrrhiza uralensis ethanol extract (GUEE) at 10$^{\circ}C$ for 12 days. Change in TBARS values was lower in the takju with GUEE as compared to control. The total viable cell count and yeasts cell count of all samples remained constant over the storage period. The brix of the takju treated with 0.5% GUEE (3.8-4.3) was higher than that of the control (3.8-4.0). Suspension stability and yellowness increased as the added concentration of GUEE increased. After 12 days of the storage, the pH level of the 0.5% GUEE takju was 3.9, which was 0.2 higher than that of control. In terms of acidity, the 0.5% GUEE takju ranged from 0.269 to 0.282, whereas the acidity of the control ranged from 0.294 to 0.302. In treated Takju with GUEE represented at treated takju with GUEE had the positive effects toward improving its preservation and quality.

• Food Engineering Progress
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• v.15 no.4
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• pp.346-354
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• 2011

This study was carried out to fortify the antimicrobial activity of yoghurt by adding liquorice extract to it. The liquorice extracts (1 mg/mL) showed relatively high antibacterial activity against H. pylori KCCM 40449 (p < 0.05). The solvent liquorice extracts of minimal inhibitory concentrations (MIC) against H. pylori KCCM 40449 were 25- 100 ${\mu}g$/mL. Lactobacillus amylovorus DU-21 with high EPS production ability were inoulated to milk after the addition of different amounts of liquorice extracts (0.0%, 0.05%, 0.1% and 0.2%). The physico-chemical characteristics of yoghurts added with liquorice extracts were examined. The initial pH, titratable acidity, viscosity and viable cell counts of the yoghurt added liquorice extracts were 3.41-3.51, 1.021-1.091%, 1,686-1,930 cp and 9.41-9.38 Log CFU/mL, respectively. The viscosity and syneresis of yoghurt were better than that of the control. Antimicrobial activity against H. pylori KCCM 40449 increased with increasing addition of liquorice extract. However, the sensory score of yoghurt added with different amounts of liquorice extracts was lower than that of the control (p < 0.05). As a result of the sensory evaluations, the flavor, taste, texture, color and overall acceptability of the yoghurt with 0.05% liquorice extract were found to be much better than those of the other groups (p < 0.05). Overall, the optimal amount of liquorice extract added in the manufacture of yoghurt was 0.05% of the total weight. Further studies on increment of antimicrobial activity and palatability of liquorice extract added yoghurt are necessary.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.228-232
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• 2008

In the present study, we investigated the glutathione S-transferase (GST) induction of medicinal plants using a cultured PC12 cells. The methanol extracts of Dendrobium nobile Lindley, Schizonepeta tenuifolia Briquet, Glycyrrhiza uralensis Fischer, Paenoia lactiflora Pall were tested. As the result, exposure of PC12 cells to G. uralensis resulted in the significant induction of GST. On the continuous experiment, G. uralensis was extracted with methanol, ethanol, and acetone. Among these extracts, methanol extracts showed the highest GST induction. The methanol extracts were further fractionated with hexane, diethyl ether, ethyl acetate, and water layer according to the degree of polarity. The diethyl ether layer showed the highest exhibited GST induction on PC12 cells. Based on these results suggest that the extracts of G. uralensis can be applicable for the development of a new antioxidant agent.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.361-366
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• 2014

In this study, Glycyrrhiza uralensis and Glycyrrhiza glabra extracts, with their countries of origin as Korea (Jecheon), Uzbekistan and China, were prepared under various extraction conditions. There were 8 extraction conditions which the licorice were subjected to, and all conditions had different extraction solvents, temperatures and times. Antimicrobial activity on skin flora was evaluated comparatively by a disc diffusion assay, broth macrodilution assay, and kill time curve assay. Based on the antimicrobial activity of their extract confirmed by disc diffusion assay, we established optimal extraction conditions. The Korean licorice extract (85% ethanol, $40^{\circ}C$, 12 h) showed the best activity amongst the samples examined. In particular, its antimicrobial activity against Propionibacterium acnes was the highest. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the licorice extracts revealed that the Korean licorice ($156{\mu}g/ml$ and $1,250{\mu}g/ml$) had better antimicrobial activity than that of the Uzbekistani licorice ($625{\mu}g/ml$ and $2,500{\mu}g/ml$) and the Chinese licorice ($625{\mu}g/ml$ and $5,000{\mu}g/ml$). Taken together, it was shown that Korean licorice extracted in group F (85% ethanol, $40^{\circ}C$, 12 h) had the highest antimicrobial activity amongst the licorices from the other countries of origin. These results also suggest that the optimal extraction conditions are 85% ethanol, $40^{\circ}C$, 12 h, and that licorice has a potential application as a natural preservative in cosmetics products, thereby replacing synthetic preservatives.

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.584-588
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• 2006

This study was carried out to optimize the conditions for the extraction of antioxidative materials from licorice root, Glycyrrhiz glabra. Chipped licorice roots were extracted with several solvents and their antioxidative activities were tested to determine the optimal extraction solvent. Among the solvents tested, 95% ethanol gave the highest free radical scavenging activity, and was therefore chosen as the optimal extracting solvent. The optimum extraction temperature and time were $20^{\circ}C$ and 12 hr, respectively. Next, the free radical scavenging activity of the ethanol extract was compared with that of other known antioxidants such as ${\alpha}-tocopherol$, butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). Ethanol extract of licorice root had greater antioxidative activity than ${\alpha}-tocopherol$ and a similar level to that of the two synthetic antioxidants (BHA and BHT). Moreover, the antioxidative activity of the ethanol extract was inhibited neither by heat treatment at $180^{\circ}C$ for 30 min nor by treatment at extreme pH. These findings suggest that ethanol extract of G. glabra may be useful as a natural antioxidant.