• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1260-1269
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• 2018

Production of good Koji primarily depends upon the selection of substrate materials and fermentative microflora, which together influence the characteristic flavor and aroma. Herein, we performed comparative metabolomic analyses of volatile organic compounds (VOCs) and primary metabolites for Koji samples fermented individually with Bacillus amyloliquefaciens and Aspergillus oryzae. The VOCs and primary metabolites were analyzed using headspace solid phase microextraction (HS-SPME) followed by gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). In particular, alcohols, ketones, and furans were mainly detected in Bacillus-fermented Koji (Bacillus Koji, BK), potentially due to the increased levels of lipid oxidation. A cheesy and rancid flavor was characteristic of Bacillus Koji, which is attributable to high content of typical 'off-flavor' compounds. Furthermore, the umami taste engendered by 2-methoxyphenol, (E,E)-2,4-decadienal, and glutamic acid was primarily detected in Bacillus Koji. Alternatively, malty flavor compounds (2-methylpropanal, 2-methylbutanal, 3-methylbutanal) and sweet flavor compounds (monosaccharides and maltol) were relatively abundant in Aspergillus-fermented Koji (Aspergillus Koji, AK). Hence, we argue that the VOC profile of Koji is largely determined by the rational choice of inocula, which modifies the primary metabolomes in Koji substrates, potentially shaping its volatolome as well as the aroma characteristics.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.418-424
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• 2014

High-acidity vinegar was manufactured using pear concentrate by fed-batch fermentation without additional nutrients, and the physicochemical properties and volatile components were investigated at different fermentation stages (Stages 1-4) and at various initial alcohol concentrations (IAC; 6-9%). The levels of reducing sugar, free amino acids, total phenolic content, total flavonoid content, and radical scavenging ability increased slightly during Stage 4 (high-acidity vinegar), which was affected by alcohol feeding. The contents of approximately 20 types of volatile compounds differed between the moderate- and high-acidity vinegar samples, as determined by solid-phase microextraction/gas chromatography-mass spectroscopy. The level of acetic acid in high-acidity vinegar increased according to the initial alcoholic content applied. The high-acidity vinegar produced by fed-batch culture at an IAC of 6-7% showed improved physicochemical and volatile properties as compared to the moderate-acidity vinegar.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1261-1272
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• 2018

The effects of Queso Blanco cheese containing Bifidobacterium longum KACC 91563 was studied on the intestinal microbiota and short chain fatty acids (SCFAs) in healthy companion dogs. There were three experimental groups with five healthy dogs each: a control group, not fed with any cheese, and groups fed with Queso Blanco cheese with (QCB) or without B. longum KACC 91563 (QC) for 8 weeks. Fecal samples were collected 5 times before, during, and after feeding with cheese. Intestinal microbiota was analyzed using two non-selective agar plates (BL and TS) and five selective agar plates (BS, NN, LBS, TATAC, and MacConkey). SPME-GC-MS method was applied to confirm SCFAs and indole in dog feces. The six intestinal metabolites such as acetic, propionic, butyric, valeric, isovaleric acid and indole were identified in dog feces. Administration of B. longum KACC 91563 (QCB) for 8 weeks significantly increased the beneficial intestinal bacteria such as Bifidobacterium ($8.4{\pm}0.55$) and reduced harmful bacteria such as Enterobacteriaceae and Clostridium (p<0.05). SCFA such as acetic and propionic acid were significantly higher in the QCB group than in the Control group (p<0.05). In conclusion, this study demonstrates that administration of Queso Blanco cheese containing B. longum KACC 91563 had positive effects on intestinal microbiota and metabolites in companion dogs. These results suggest that Queso Blanco cheese containing B. longum KACC 91563 could be used as a functional food for companion animals and humans.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.661-668
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• 2018

Geosmin is volatile metabolites produced by a range of filamentous cyanobacteria which causes taste and odor problems in drinking water. Molecular ecological methods which target biosynthetic genes (geoA) are widely adopted to detect geosmin-producing cyanobacteria. The aim of this study was to investigate the potential production capability of 8 strains isolated from the Nakdong River. Ultimately, a suggestion for a genetical monitoring tool for the identification of geosmin producers in domestic waters was to be made. Geosmin was detected using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS) in two strains of Dolichospermum plactonicum (DGUC006, DGUC012) that were cultured for 28 day. The highest concentrations during the experiment period was $17,535ngL^{-1}$ and $14,311ngL^{-1}$ respectively. Additionally, geoA genes were amplified using two primers (geo78F/971R and geo78F/982R) from strains shown to produce geosmin, while amplification products were not detected in any of non-producing strains. PCR product (766 bp) was slightly shorter than the expected size for geosmin producers. According to the BLAST analysis, amplified genes were at nucleotide level with Anabaena ucrainica (HQ404996, HQ404997), Dolichospermum planctonicum (KM13400) and Dolichospermum ucrainicum (MF996872) between 99 ~ 100 %. Both strains were thus confirmed as potential geosmin-producing species. We concluded that the molecular method of analysis was a useful tool for monitoring potential cyanobacterial producers of geosmin.

• 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 Forest and Environmental Science
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• v.26 no.3
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• pp.209-217
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• 2010

The volatile aroma of fresh leaves is one of main factor in taste of all the edible green plants. The volatile aroma in almost edible green leaves are suggested as essential oil compounds. Ligularia fischeri, Synurus deltoides, Ligularia fischeri var. spiciformis and Aster scaber are one of the favourable edible green plants in Korea. In this study, volatile aroma compounds from Ligularia fischeri and Ligularia fischeri var. spiciformis species were analyzed by the SPME/GC/MSD method. Ligularia fischeri had 78 volatile aroma compounds such as D-limonene(20.28%), ${\alpha}$-pinene(dextro, 14.15%), L-${\beta}$-pinene(12.85%), 3-carene, ${\beta}$-cubebene(10.39%), etc. Ligularia fischeri var. spiciformis had 83 volatile aroma compounds such as D-limonene(36.97%), ${\beta}$-cubebene(13.95%), L-${\beta}$-pinene(13.38%), ${\alpha}$-pinene(dextro, 4.76%), caryophylle-ne(3.33%) etc. Conclusively, the commom volatile aroma compounds in Ligularia fischeri and Ligularia fischeri var. spiciformis leaves were D-limonene, ${\alpha}$-pinene, L-${\beta}$-pinene, ${\beta}$-cubebene, Caryophyllene, ${\alpha}$-farnesene, terpinolen. However, the composition and amount of volatile aroma compounds were very different between the two species.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.109-109
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• 2020

꽃차(Flower tea)는 최근 다양한 제품이 개발되고 소비가 확대되는 등 그 산업적 가치가 증대하고 있다. 꽃차의 향기 특성은 우렸을 때 나타나는 색깔 및 인체에서의 생리활성과 더불어 주요한 꽃차 품질결정 요소이다. 본 연구는 꽃차로의 이용이 활발한 국화과 식물 중 구절초(Dendranthema zawadskii var. latilobum), 국화(Chrysanthemum morifolium), 노랑색 및 주황색 마리골드(Tagetes erecta 'Yellow' and 'Orange'), 그리고 캐모마일(Matricaria chamomilla)의 향기 성분특성을 구명하기 위하여 제조된 꽃차를 headspace-solidphase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS)를 이용하여 분리, 동정하였다. 국화과 꽃차로부터 총 117종의 휘발성 성분이 확인되었는데, 각 꽃차 종류별 동정된 휘발성 성분의 개수, 주요 3개 휘발성 성분과 전체 향기성분 peak중 이들이 차지하는 구성비율(%)은 다음과 같았다: 구절초 64종, camphor (31%), α-pinene(14%), camphene(14%); 국화 60종, camphor(15%), chrysantheny acetate(13%), eucalyptol (11%); 마리골드 '옐로우' 53종, 2,4-heptadienal(26%), trans-isocarveol(21%), cis-β-Copaene(18%); 마리골드 '오렌지' 61종, β-caryophyllene(16%), β-ocimene epoxide(12%), β-ocimene(12%); 캐모마일 50종, β-farnesene(63%), nonane(9%), spathulenol(5%). 국화과 꽃차 5종 모두에서 공통적으로 검출된 성분은 β-caryophyllene, α-pinene, β-farnesene 등 10종이었으며 마리골리 '옐로'는 '오렌지'와 주요 향기성분의 조성에서 뚜렷한 차이를 나타내었다. 비록 그 함량은 낮았으나 구절초, 국화, 마리골드 '오렌지', 그리고 캐모마일은 각각 10종, 12종, 3종 및 13종이었다. 마리골드 '엘로'의 경우 검출된 모든 향기성분은 마리골드 '오렌지'나 다른 국화과 식물의 꽃차에서도 검출된 바, 향기 성분이 다양성이 다소 낮게 나타났다.

• Journal of Apiculture
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• v.32 no.3
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• pp.139-146
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• 2017

Floral scent emitted from many plants is the critical factors for pollinator attraction and defense for adaptation in environments. The fragrance components of flowers are different in composition by geographical origins, climate factors and the development stages of flowers. In the present study, we investigated the volatile-floral compounds in flowers of Robinia pseudoacacia L. and defined the chemical contribution for flowering periods. The volatile compounds analysis was performed by gas chromatography with mass selective detector after solid phase microextraction (SPME). We reported different compositional features of fragrance compounds according to flowering periods. The abundant compounds identified in stage 1 were ${\alpha}$-pinene (66.80%) and ${\beta}$-pinene (26.53%). Those of the stage 2 were (Z)-${\beta}$-ocimene (37.57%), ${\alpha}$-pinene (15.16%), benzaldehyde (16.63%), linalool (12.13%). The volatiles of stage 3 comprised an abundance of (Z)-${\beta}$-ocimene (64.94%), ${\alpha}$-pinene (9.84%), linalool (8.92%), benzaldehyde (1.71%). Leaf volatiles were distinct from those in the reproductive plant parts by their high relative amount of (E)-${\beta}$-ocimene (23.50%) and (Z)-3-Hexenyl acetate (27.87%). Differences in flower scents of the different stages and leaves are discussed in light of biochemical constraints on volatile chemical synthesis and of the role of flower scent in evolutionary ecology of R. pseudoacacia.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1409-1416
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• 2007

Seven selected commercial pure or refined olive oils were obtained from the market, and their physicochemical properties and volatile characterizations were investigated. Fatty acid profiles of the analyzed olive oils showed oleic $(61.2{\sim}74.7mole%)$, palmitic $(10.2{\sim}16.8mole%)$, linoleic $(9.4{\sim}18.0mole%)$, stearic $(1.9{\sim}3.0mole%)$, palmitoleic $(0.7{\sim}2.4mole%)$ and linolenic acid $(0.5{\sim}0.9mole%)$. According to Hunter#s color measurement, pure or refined olive oils showed $L^*$ value of $92.2{\sim}99.0$, $a^*$ value of $-22.2{\sim}-3.2$, and $b^*$ value of $18.5{\sim}55.0$. Their total phenol contents ranged from 1.9 to $13.3mg/100g$ while ${\alpha}-tocopherol$ content showed $7.91{\sim}13.88mg/100g$. Oxidation stability of the pure or refined olive oils were observed by Rancimat. The induction period ranged from 17.37 to 34.72 hr while their POV were $6.83{\sim}20.31meq/kg$ oil. Electronic nose and gas chromatograph-mass spectrometry with head-space solid phase microextraction were applied to identify and discriminate the volatile compounds and flavors in pure or refined olive oils, respectively.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.524-528
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• 2020

The aim of this study was to enhance the use of wheat bran in lactic acid bacteria (LAB) fermentation. LAB fermentation of wheat bran and the flavor components and amino acids of fermentation products were analyzed using gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC). The results showed that total flavor components increased by 93% and 73% in the animal-based LAB mixture (T2) and plant-based LAB mixture (T3), respectively, after fermentation. Among these components, 2,3-butanedione (diacetyl), known for its buttery flavor, was detected at concentrations of 18.44 ng/g (T2) and 16.95 ng/g (T3). Levels of hexanal and nonanal, which causes off-flavor components in wheat bran, dramatically decreased after T2 fermentation; similarly, levels of total free amino acids decreased by 37.6% (T2) and 36.7% (T3) after fermentation. This may explain why some components were bound to volatile compounds during LAB fermentation. These results suggest that LAB-fermented wheat bran is a potential value-added food material.