• Korean Journal of Food Science and Technology
• /
• v.43 no.5
• /
• pp.570-576
• /
• 2011

The effect of nuruks and crude amylolytic enzyme on free amino acid and volatile components of brown rice vinegar prepared by static cultures was investigated. Five groups consisted of AV (100% nuruk without crude amylolytic enzyme), BV (75% nuruk; 25% crude amylolytic enzyme), CV (50% nuruk; 50% crude amylolytic enzyme), DV (25% nuruk; 75% crude amylolytic enzyme) and EV (100% crude amylolytic enzyme without nuruk). Free amino acid content in AV vinegar (132.06 mg%) was lower than the others (184.56-191.22 mg%). Acetic acid, 3-methyl butyl acetate, acetoin and isoamyl alcohol were major volatile components as analyzed using gas chromatography-mass spectrometry after headspace solid-phase microextraction. Acetic acid in AV and EV samples represented 67.56% and 55.53% of total GC peak area, respectively. E-nose provided different patterns in each case showing variation in sensory properties.

• Korean Journal of Food Science and Technology
• /
• v.41 no.5
• /
• pp.587-591
• /
• 2009

Volatiles in Artemisia princeps Pampan. cv. sajabal (sajabalssuk) and A. princeps Pampan. (ssuk) treated with different processing were analyzed using headspace-solid phase microextraction (HS-SPME)/gas chromatography- a mass selective detector (GC-MS). Sajabalssuk and ssuk were treated with steam distillation (SD) and freeze-dried/steam distillation (FD/SD) while controls were raw sajabalssuk and raw ssuk. Sajabalssuk had significantly more total volatiles than ssuk in control and FD/SD treated samples (p<0.05). Major volatiles in raw sajabalssuk were 2-hexenal, 1,8-cineol, trans-caryophyllene, and hexanal while those in raw ssuk were 1-hexanol, ${\beta}$-myrcene, limonene, and 2-hexenal, which implies that substantial lipid oxidation occurred in raw samples. Sajabalssuk with SD and FD/SD treatment had higher peak areas of 1,8-cineole, 4-terpineol, 1-octen-3-ol, and ${\alpha}$-terpineol while ssuk with SD and FD/SD treatment possessed 1,8-cineol, camphor, borneol, artemisia ketone, ${\alpha}$-thujone, and 1-octen-3-ol, which showed that steam distillation produced more volatiles from terpenoids than raw samples. Based on the results of HS-SPME/GC-MS, relative amounts of volatiles from lipid oxidation including 2-hexenal, hexanal, and 1-hexanol were reduced in sajabalssuk and ssuk with freeze-drying and/or steam distillation treatment.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.2
• /
• pp.199-209
• /
• 2018

Volatile organic compounds (VOCs) are increasingly been recognized as the chemical mediators of mold interactions, shaping their community dynamics, growth, and metabolism. Herein, we selectively examined the time-correlated (0 D-11 D, where D = incubation days) effects of intraspecies VOC-mediated interactions (VMI) on Aspergillus oryzae KCCM 60345 (S1), following co-cultivation with partner strain A. oryzae KACC 44967 (S2), in a specially designed twin plate assembly. The comparative evaluation of $S1_{VMI}$ (S1 subjected to VMI with S2) and its control ($S1_{Con}$) showed a notable disparity in their radial growth ($S1_{VMI}$ < $S1_{Con}$) at 5 D, protease activity ($S1_{VMI}$ > $S1_{Con}$) at 3-5 D, amylase activity ($S1_{VMI}$ < $S1_{Con}$) at 3-5 D, and antioxidant levels ($S1_{VMI}$ > $S1_{Con}$) at 3 D. Furthermore, we observed a distinct clustering pattern for gas chromatography-time of flight-mass spectrometry datasets from 5 D extracts of $S1_{VMI}$ and $S1_{Con}$ in principle component analysis (PC1: 30.85%; PC2: 10.31%) and partial least squares discriminant analysis (PLS-DA) (PLS1: 30.77; PLS2: 10.15%). Overall, 43 significantly discriminant metabolites were determined for engendering the metabolic variance based on the PLS-DA model (VIP > 0.7, p < 0.05). In general, a marked disparity in the relative abundance of amino acids ($S1_{VMI}$ > $S1_{Con}$) at 5 D, organic acids ($S1_{VMI}$ > $S1_{Con}$) at 5 D, and kojic acid ($S1_{VMI}$ < $S1_{Con}$) at 5-7 D were observed. Examining the headspace VOCs shared between S1 and S2 in the twin plate for 5 D incubated samples, we observed the relatively higher abundance of C-8 VOCs (1-octen-3-ol, (5Z)-octa-1,5-dien-3-ol, 3-octanone, 1-octen-3-ol acetate) having known semiochemical functions. The present study potentially illuminates the effects of VMI on commercially important A. oryzae's growth and biochemical phenotypes with subtle details of altered metabolomes.

• Korean Journal of Food Science and Technology
• /
• v.45 no.3
• /
• pp.267-273
• /
• 2013

We aimed to improve the flavor quality of plain yogurt, which is known to be sour and less desirable in flavor, varying concentrations of a buckwheat saccharification solution (BSS) were added to milk, followed by fermentation with commercially available mixed strains of lactic acid bacteria. Volatile compounds were analyzed using the gas chromatography-headspace-solid phase microextraction (GC-HS-SPME) method. Fermentation properties, including pH, titratable acidity, viable cells, viscosity, and color value were also measured. Eleven volatile compounds were identified with GC-MS. Of which, diacetyl, butanoic acid, and 2-heptanone proportionally increased as the levels of BSS increased. Undesirable compounds such as acetic acid and 2-butanone, decreased as BSS concentration increased. Fermentation properties were significantly altered with the addition of BSS. Our findings indicate that the flavor quality of plain yogurt can be improved by adding BSS for fermentation, with an additional health benefit from buckwheat.

• Korean Journal of Food Science and Technology
• /
• v.42 no.5
• /
• pp.533-540
• /
• 2010

Effects of pH (1.8-10.2) and time (56 sec-15 min 4 sec) at high hydrostatic pressure (500 MPa) on the reduction of volatile compounds in garlic were studied. Volatile components of garlic were obtained from the headspace, analyzed, and identified by gas chromatography (GC)-mass spectrometry and an electronic nose. Nineteen sulfur compounds were identified as major compounds in garlic, and furan, aldehydes, alcohols, and ketones were also detected. Off-flavor compounds were more effectively reduced under strong acidic conditions. As the residence time at 500 MPa increased from 56 sec to 15 min 4 sec, the total amount of volatile compounds decreased significantly. The total amount of sulfur compounds decreased about 70% compared to those of raw garlic when the garlic was soaked in buffer (pH 6.0) and treated at 500 MPa for 15 min 4 sec. A principal component analysis showed that the off-flavors of garlic were reduced by the operating time of high hydrostatic pressure as well as pH treatment. The correlation coefficient of the results between GC and the electronic nose analysis was 0.9620. Therefore, pH and high hydrostatic pressure treatment could be used as an efficient method for reducing of garlic off-flavor.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.12
• /
• pp.1871-1880
• /
• 2014

Headspace volatile compounds of leaf, stem, and root of Peucedanum japonicum Thunberg (PJT) harvested in March and July were isolated, separated, and identified by using a combined system of solid phase microextraction and gas chromatography/mass spectrometry. Identified numbers of volatile compounds were 72, 75, and 63 in March PJT as well as 78, 73, and 69 in July, respectively. Total compounds identified from PJT consisted of alcohols (1~7), aldehydes (7~15), esters (1~4), hydrocarbons (5~9), ketones (1~2), monoterpenes (13~16), monoterpene alcohols (1~5), monoterpene aldehydes (2~4), monoterpene esters (1~4), monoterpene ketones (1~2), sesquiterpenes (16~24), and miscellaneous compounds (2~3). Major volatile compounds of PJT were monoterpenes at all harvest times and in all parts of PJT. The amounts of ${\beta}$-pinene in leaf and stem harvested in March were highest in monoterpenes, followed by ${\alpha}$-pinene and ${\beta}$-myrcene. However, amounts of volatile compounds of monoterpenes in leaf and stem from July PJT were in the decreasing order of ${\beta}$-pinene, ${\beta}$-phellandrene, and ${\beta}$-myrcene. Of the 39 sesquiterpenes identified in PJT, (E)-caryophyllene in March leaf was the most abundant volatile compound, followed by acoradiene in March leaf, ${\beta}$-elemene, and ${\alpha}$-copaene in July stem.

• Korean Journal of Food Science and Technology
• /
• v.47 no.2
• /
• pp.137-144
• /
• 2015

Although instant coffee is less palatable than freshly brewed coffee, it is widely consumed primarily due to its convenience. Frequently, instant coffee is consumed in the form of a coffee-mix. It contains coffee creamer or dried skim milk, and sugar in addition to soluble coffee. The aim of this study was to investigate the volatile aroma compounds (VACs) of instant black coffee mixed with coffee creamer or dried skim milk by Gas Chromatography-Headspace-Solid Phase Microextraction (GC-HS-SPME) and sensory evaluation. A total of 16 different coffee samples including instant black coffee and coffee mixes with coffee creamer or dried skim milk, were chosen for this study. The coffee samples contained several common VACs such as pyrazine, pyridine, and pyrrole. Sensory evaluation indicated that the flavor intensity of coffee mix was less pronounced than that of instant black coffee alone. Coffee creamer and skim milk had little distinctive aroma per se; however, they significantly contributed to the flavor profile of coffee mixes, suggesting that coffee creamer and skim milk acted as flavor modifiers in coffee mix.

• Korean Journal of Food Science and Technology
• /
• v.44 no.4
• /
• pp.383-389
• /
• 2012

Green tea leaves grown in Jeju island were harvested at different times in 2010 and 2011. Green teas harvested in 2010 experienced higher effective accumulative temperature than green teas harvested in 2011. The free and bound volatile compounds in green tea were analyzed using headspace-solid phase microextraction gas chromatography (GC) and GC-mass spectrometry. All green teas contained the 6 major volatile compounds ${\alpha}$-methylbutanal, pentanal, (E)-2-hexen-1-ol, ${\beta}$-linalool, geraniol and ${\alpha}$-farnesene. After enzyme treatment, (Z)-3-hexen-1-ol, benzaldehyde, (Z)-3-hexenyl acetate, ${\beta}$-linalool and geraniol were increased in all green teas. (Z)-3-hexen-1-ol increased significantly in green tea harvested in 2010, and benzaldehyde increased widely in green tea harvested in 2011. However, the total volatile compounds in green teas harvested in 2011 were remarkably decreased in comparison to harvested in 2010. It was confirmed that free and bound volatile compounds in green tea are affected by low winter temperatures.

• Food Science and Preservation
• /
• v.30 no.3
• /
• pp.492-501
• /
• 2023

In this study, we wanted to understand the impact of different decaffeination processes on aroma compounds of coffee. Therefore, we analyzed differences in physical characteristics and volatile aroma compounds profiles of regular coffee (RC), Swiss water process decaffeinated coffee (SWDC), and supercritical CO₂ decaffeinated coffee (SCDC) after roasting the coffee beans. The electronic nose analysis identified RC and SCDC as different groups which indicates that these groups volatile aroma compound compositions were different. The principal component analysis of volatile compound patterns identified using an electronic nose indicated that there was a large difference in volatile compounds between RC, which was not decaffeinated, and both decaffeinated SWDC and SCDC. The major aroma compounds of RC, SWDC and SCDC were propan-2-one and hexan-2-one which are ketone, and hexanal and (E)-2-pentenal which are aldehyde and 3-methyl-1-butanol which is an alcohol. After roasting, the composition of major volatile compounds appearing in the beans was similar, but the relative odor intensity was different. We identified 28 volatile aroma compounds from RC, SWDC, and SCDC using headspace-solid phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS), and analyzed 10 major compounds that were present in high abundance, including furfural, 2-furanmethanol, 2,5-dimethylpyrazine, and 2-ethyl-3-methylpyrazine.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.61 no.4
• /
• pp.242-250
• /
• 2016

Although rice has been cultivated as a major food crop for approximately 5,000 years, the interest of customers in 'scented rice' is a recent trend in the Korean market. As a part of developing a germinated scented rice variety, the newly bred scented rice variety 'Cheonjihyang-1 se' was germinated for 24 h, and changes in profiles of flavor-related volatiles, lipophilic phytonutrients, and fatty acids were investigated. The profiling of volatile compounds by using a headspace-gas chromatography-mass spectrometry (HS-GC-MS) revealed a total of 56 odor-active flavoring compounds; 52 at the pre-germination stage, 51 at the post-germination stage, and 47 common at both stages. The major flavoring compounds were nonanol and benzene, which constituted 11.5% and 6.6%, respectively, of the total peak area in pre-germinated rice, and 19.4% and 6.5%, respectively, in post-germinated rice. Germination induced an increase in 13 flavoring compounds, including 3,3,5-trimethylheptane and 1-pentadecene, which increased by 763 and 513%, respectively by germination. However, we observed a germination-induced decrease in most of the other flavoring compounds. Especially, the most important scented rice-specific popcorn-flavoring compound, 2-acetyl-1-pyrroline, showed 89% decrease due to germination. Furthermore, the germination of scented rice induced a decrease in the content of various phytonutrients. For example, the total contents of phytosterols, squalene, and tocols decreased from 207.97, 31.74, and $25.32{\mu}g\;g^{-1}$ at pre-germination stage down to 136.66, 25.12, and $17.76{\mu}g\;g^{-1}$, respectively at post-germination stage. The fatty acid compositions were also affected by germination. The composition of three major fatty acids, linoleic, oleic, and palmitic acids, increased from 36.6, 34.2, and 24.4%, respectively, at the pre-germination stage to 37.9, 36.9, and 20.7%, respectively, at the post-germination stage. All these results suggested significant changes in the flavor-related compounds and phytonutrients of the scented rice variety 'Cheonjihyang-1 se' during the process of germination, and subsequently the need for developing a more precise process of germination to enhance the flavor and nutritional quality of the germinated scented rice products.