• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.307-316
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• 2022

Yeasts play an important role in spontaneous fermentation of traditional alcoholic beverages. Our previous study revealed that a mixed-consortia of both Saccharomyces and non-Saccharomyces yeasts were responsible for fermentation of khadi, a popular, non-standardized traditional beverage with an immense potential for commercialization in Botswana. Functional characterization of isolated fermenting yeasts from mixed consortia is an indispensable step towards the selection of potential starter cultures for commercialization of khadi. In this study, we report the characterization of 13 khadi isolates for the presence of brewing-relevant phenotypes such as their fermentative capacity, ability to utilize a range of carbon sources and their ability to withstand brewing-associated stresses, as a principal step towards selection of starter cultures. Khadi isolates such as Saccharomyces cerevisiae, Saccharomycodes ludwigii and Candida ethanolica showed good brewing credentials but Lachancea fermentati emerged as the isolate with the best brewing attributes with a potential as a starter culture. However, we were then prompted to investigate the potential of L. fermentati to influence the fruity aromatic flavor, characteristic of khadi. The aroma components of 18 khadi samples were extracted using headspace solid phase micro-extraction (HS-SPME) and identified using a GC-MS. We detected esters as the majority of volatile compounds in khadi, typical of the aromatic signature of both khadi and L. fermentati associated fermentations. This work shows that L. fermentati has potential for commercial production of khadi.

• Journal of Food Hygiene and Safety
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• v.24 no.3
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• pp.273-276
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• 2009

We investigated eight active natural antimicrobials for preservation of functional beverages that are usually degraded by yeasts rather than by bacteria due to a high sugar content and a low pH. Five strains of yeasts (S. cerevisiae, Z. bailii, P. membranaefaciens, C. albicans, and P Anomala) were tested with eight natural antimicrobial agents ($\varepsilon$-polylysine, yucca extract, vitamin $B_1$ derivative, scutellaria baicalensis extract, chitooligosaccharid, allyl isothiocyanate, sucrose-fatty acid ester, and oligosaccharide). The lowest minimal inhibitory concentrations (MIC) were 10 ppm for oligosaccharide and sucrose-fatty acid ester against S. cerevisiae and Z. bailii, 10 ppm for allyl isothiocynate against P. membranaefaciens and C. albican, and 10 ppm for allyl isothiocynate and oligosaccharide against P. anomala. No growth were observed for five kinds of yeasts in functional beverages containing sodium benzonate at concentration of 0.015% or higher. The resistance of S. cerevisiae, Z. bailii, and P. Anomala against natural antimicrobial agents was lower than those of P. membranaefaciens and C. albican. Allyl isothiocyanate, oligosaccharide, and sucrose-fatty acid ester showed the highest antimicrobial activities among the eight tested antimicrobials. These results can be applied to develop new natural antimicrobial agents to improve microbial quality of functional beverages.

• Journal of Food Hygiene and Safety
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• v.24 no.3
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• pp.189-193
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• 2009

The purpose of this study was to investigate the antimicrobial activities of natural antimicrobials (10 formulas, $F1{\sim}F10$) against yeasts in functional beverages. The growth rates of yeasts were different with the ten different natural antimicrobial formulas tested. Yeasts grew for 14 days and the antimicrobial effect was observed between 14 and 18 days. Levels of S. cerevisiae, Z. bailii, and P. membranaefaciens were reduced to the limit of detection (ND) < 10 CFU/mL) after 28 days. Resistance against the antimicrobial effect was greatest for P. membranaefaciens, which grew to a level of $0.12{\sim}1.48\;\log_{10}\;CFU$/mL after 14 days and was reduced to a level of $1.61{\sim}3.55\;\log_{10}\;CFU$/mL after 28 days. The resistance of C. albicans was also high with a growth level of $0.13{\sim}1.28\;\log_{10}\;CFU$/mL after 14 days and reduction to $1.51{\sim}5.30\;\log_{10}\;CFU$/mL after 28 days. The antimicrobial effect of F10 was strongest for P. membranaefaciens. Every treatment reduced the microbial levels to $2.68{\sim}5.62\;\log_{10}\;CFU$/mL after 6 months. F2, F4, F5, F6, and F10 reduced the C. albicans level to ND after 28 days while F1, F3, F8, and F9 reduced yeasts to the ND level after 6 months. The antimicrobial activities observed here will be useful for development of natural antimicrobials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1422-1429
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• 2016

Kombucha is a slightly sour beverage fermented by symbiotic micro-organisms, including bacteria and yeasts. In this study, we examined the biological activities of citrus Kombucha (CK) produced by addition of citrus extract to original Kombucha (K). After fermentation for 10 days, radical scavenging activity examined by ABTS and DPPH assays increased by approximately 20% compared to that of K. Moreover, content of total phenolic compounds significantly increased by 60% compared to that of K. Cell proliferation assays utilizing MTT showed that CK treatment significantly inhibited growth of bladder cancer cells, T-24 and 5637, in a dose-dependent manner with $IC_{50}$ values of 4 and 7 mg/mL, respectively. Annexin V staining showed that CK treatment led to apoptosis of cells in a dose-dependent manner. T-24 cells were more sensitive to CK treatment than 5637 cells, as 8 mg/mL of CK resulted in 97% apoptosis of T-24 cells. Western blotting showed that CK treatment led to up-regulation of apoptotic proteins, including caspases-3, -8, -9, and PARP, in bladder cells not in K-treated cells. Taken together, these results demonstrate that CK may be developed as a functional beverage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1838-1842
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• 2016

Kombucha (K) is a fermented beverage made from black tea by symbiotic micro-organisms of bacteria and yeasts. To enhance bio-activities of K, we produced citrus/green tea Kombucha (CK) by adding extracts of citrus peel and green tea obtained from Jeju Island. ORAC assays showed that anti-oxidative capacity of CK increased by approximately 3-folds compared to K. We examined anti-cancer properties of extracts from citrus peel and/or green tea using 5637 human bladder cancer cells and B16F10 murine melanoma cells. Proliferation of B16F10 cells was markedly inhibited at concentrations higher than $10{\mu}L/mL$. At a concentration of $20{\mu}L/mL$, anti-cancer activities of extracts were in the order of citrus peel< green tea< combination of both. Interestingly, a combination of both extracts showed a synergistic effect on inhibition of growth of cancer cells. CK fermented with citrus peel and green tea extracts showed enhanced anti-cancer activity compared to K. Cytotoxicity of CK on RAW 264.7 murine macrophages was negligible up to $100{\mu}L/mL$. Taken together, these results indicate that citrus Kombucha is safe to be developed as a functional beverage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.9
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• pp.1264-1269
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• 2015

To evaluate the functional effect of ornithine produced by isolated lactic acid bacteria, we examined the anti-lipid accumulation effect of ornithine produced by isolate lactic acid bacteria on 3T3-L1 cells. Lactic acid bacteria (Pediococcus strain) were isolated from nuruk, which is made from wheat, rice, and barley (whole grain, grits, or flour) by fermenting microorganisms (Aspergillus, Rhizopus, and yeasts). Pediococcus strain was identified by 16S rDNA sequencing analyses, and cells were collected by centrifugation and developed as an ornithine starter. makgeolli, an ornithine-containing Korean traditional alcoholic beverage, was made with isolated lactic acid bacteria and arginine. makgeolli was made with the help of ornithine starter using a makgeolli making kit. We evaluated the anti-proliferation effect of ornithine makgeolli on 3T3-L1 cells. To determine the anti-proliferation effect of ornithine makgeolli on preadipocytes, lipid droplets were quantified and stained with Oil Red O. makgeolli made with ornithine starter and arginine showed a 3-fold higher concentration of ornithine compared to makgeolli without starter and arginine. In the results of 3T3-L1 cell line experiment, lipid accumulation was significantly reduced by adding 0.05 mg/mL of ornithine makgeolli compare to the control (adipocyte without sample). In conclusion, ornithine makgeolli containing ornithine starter isolated from nuruk showed an anti-lipid accumulation effect with increased ornithine content without toxicity.