• Applied Biological Chemistry
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• v.34 no.2
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• pp.149-153
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• 1991

Several commercial soybean oils were stored at $20^{\circ}C,\;40^{\circ}C$ and $60^{\circ}C$ with daily exposure of fluorescent light for 12 hours and evaluated their rancidity by headspace gas chromatographic analysis of pentanal and hexanal. The data of gas chromatographic analysis was compared with organoleptic flavor evaluation. For headspace gas chromatographic analysis, the volatile compounds were recovered by porous polymer trap and flushed into a fused silica capillary column at $250^{\circ}C$, The pentanal and hexanal separated were identified by gas chromatography and gas chromatography-mass spectrometric method. The results showed that the contents of pentanal and hexanal were linearly increased during storage for 100 days. A very simple linear relationship was found between organoleptic flavor scores and amounts of two volatile compounds with very high correlation coefficient. A similar linear relationship was also obtained for acid and peroxide value with sensory data. This results suggested the possible implication of pentanal and hexanal as an quality index for rancidity evaluation of soybean oil.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.36-41
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• 1992

Several commercial cottonseed, corn and rapeseed oils were stored at $60^{\circ}C\;and\;70^{\circ}C$ with daily exposure of fluorescent light for 12 hours and evaluated their rancidity by headspace gas chromatographic analysis of pentanal and hexanal. The data of gas chromatographic analysis was compared with organoleptic flavor evaluation. For headspace gas chromatographic analysis, the volatile compounds were recovered by porous polymer trap and flushed into a fused silica capillary column at $250^{\circ}C$. Twenty-three GC peaks were identified on the basis of relative retention time of reference compounds and gas chromatography-mass spectrometry. The results showed that the contents of pentanal and hexanal were linearly increased during storage. A very simple linear relationship was found between organoleptic flavor scores and amounts of two volatile compounds with very high correlation coefficient. This results suggested the possible implication of pentanal and hexanal as an quality index for rancidity evaluation of cottonseed, corn and rapeseed oils.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.154-161
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• 1991

An objective method for measuring rancidity in soybean oil was developed based on the volatile contents obtained by headspace gas chromatographic analysis. Apparatus for headspace volatile cold trapping-thermal desorption was described, designed to collect and analyze volatiles of soybean oil. Samples of commercially processed soybean oil were stored under controlled condition and then evaluated for flavor by a eight member trained panel and for volatile contents by headspace gas chromatographic analysis. Twenty-three GC peaks were identified on the basis of relative retention time of reference compounds and gas chromatography-mass spectrometry. The volatile compounds identified were autoxidation products of principal unsaturated fatty acids of soybean oil. The simple linear regressions of flavor score with the pentanal or hexanal contents in aged soybean oil gave correlation coefficient of 0.990 and 0.994. respectively. Pentanal and hexanal contents could be used as a potentially useful index for predicting flavor scores of soybean oil.

• Food Science of Animal Resources
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• v.25 no.1
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• pp.78-83
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• 2005

Purge & Trap method was applied to perform more simple and rapid detection for analysis of volatile flavor compounds in milk. Maximal sampling of 30 mL milk for glass flask sparger was treated by He gas purging for 2 hours. Reported major volatile compounds were detected by GC-MS after 2 hours absorption and desorbed from Purge & Trap equipped with Tenax trap. Volatile flavor compounds were analyzed by Purge & Trap and GC-MS to investigate the changes of flavor components in milk between raw and deodorized milk. Fourteen volatile compounds including acetaldehyde, ethanol, 2-propanone, dimethyl sulfide, isobutanal, 3-methyl 2-butanone, 2-butanone, 3-methyl butanal, pentanal, 3-hydroxy-2-butanone, methyl disulfide, hexanal, and 2 others were detected. Six compounds such as ethanol, dimethyl sulfide, pentanal, 3-hydroxy-2-butanone, and methyl disulfide were completely eliminated after deodorization treatment. Four compounds such as 3-methyl 2-butanone, 2-butanone, 3-methyl butanal, and an unknown compound 81 (M/sup +/) were also decreased after raw milk was deodorized. The other four compounds such as acetaldehyde, 2-propanone, hexanal, and an unknown compound (M/sup +/) were not decreased.

• The Korean Journal of Food And Nutrition
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• v.13 no.2
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• pp.118-124
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• 2000

Lipoxygenase(LOX) in soybeans is responsible for beany flavors which limit the wide utilization of soybeans to foods. This study was conducted to analyze beany flavor compounds of the normal Hwagkeumkong and LOX-deficient soybean cultivars, Jinpumkong which lacks L-2, L-3, and Jinpumkong 2 which lacks all L-1, L-2, L-3. Using the combination of dynamic headspace sampling and gas chromatography-mass selective detector(DHS-GC-MSD) for analyzing volatile compounds, hexanal and hexanol were identified in whole soy flour of all three soybena cultivars. Hwangkeumkong had more volatile compounds than Jinpumkong and Jinpumkong 2 in defatted soy flour. Hexanal and acetic acid were identified in soy milk of all three soybean cultivars but Hwangkeumkong had more volatile compounds than Jinpumkong 2. From the analysis with a static headspace sampling(SHS) and GC-MSD the major compounds were hexanal, acetic acid, 1-hexanol, and 1-octen-3-ol. The content of acetic acid was similar among three cultivars. But contents of hexanal and pentanal in Jinpumkong 2 were less than that of Jinpumkong and Hwangkeumkong. Using GC-FID, Jinpumkong 2 had less contents of hexanal and pentanol than Hwangkeumkong in whole soy flour and defatted soy flour. In this study, LOX-deficient soybean cultivars showed less hexanal, pentanol and other compounds than the normal Hwangkeumkong. However quite amount of beany flavor compounds were identified in Jinpumkong and Jinpumkong 2. So further studies are required to characterize LOX isozymes, to understand the mechanisms of beany flavors production, and to develop some other methods for removing beany flavor.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.15-20
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• 1997

Changes in antioxidative substances-sesamol, sesamin and sesamolin - and mineral contents of sesame oil during refining processes have been studied to investigate the oxidative stability of oils during the storage at $70^{\circ}C$. Fe, Cu, Mg and Zn were nearly removed from the oil by the degumming process. During storage, the changes of total volatile contents in crude and degummed sesame oil were not noticeable but those in alkali-refined and deodorized sesame oil were increased at early period of the storage. The increases of hexanal and pentanal were most noticeable and their concentration was increased markedly in alkali-refined, bleached and deodorized sesame oil at early period of the storage. During refining processes and storage, sesamin was relatively stable but the content of sesamolin was decreased. The content of sesamol was decreased until alkali-refining process but increased during a bleaching process. The content of sesamolin tended to decrease with increasing of sesamol during storage.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.738-741
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• 2006

Volatile flavor compounds in commercial sterilized milk were analyzed and identified by static headspace, purge-and-trap, and solid-phase microextraction (SPME) methods. About 20 volatile compounds were identified by GC/MS, and aldehydes and ketones were the most distinctive and abundant compounds. Static headspace analysis allowed the identification of only the most abundant compounds, such as acetone. Five ketones (acetone, 2-butanone, 2-pentanone, 2-heptanone, 2-nonanone), four aldehydes (2-methylbutanal, pentanal, hexanal, benzaldehyde) and dimethyl sulfide, all of which were responsible for off-flavor in milk, were found by the purge-and-trap and SPME methods. The two methods differed little in their release of these compounds, but they yielded different amounts in the extraction.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.623-625
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• 1997

This study was carried out to investigate the effect of storage period on flavor components of Korean kiwifruits (Actinidia deliciosa Planch.) stored at $20^{\circ}C$. The major volatile components of Korean kiwifruits analyzed by GC and GC-MS were pentanal, methyl butanoate, ethyl pentanoate, heptanone, (E)-2-hexenal, ethyl hexanoate, 1-hexanol, cyclohexanol, butyl hexanoate, linalool oxide, linalool, butyl heptanoate, methyl benzoate, ethyl benzoate. Among them, (E)-2-hexenal was the major component in premature fruit but on further ripening ethyl butanoate began to dominate the component profile.

• Applied Biological Chemistry
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• v.36 no.2
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• pp.111-114
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• 1993

The volatile components of cooked glutinous rice were investigated. Among more than 100 volatile components of fresh cooked rice, the predominant one was hexanal followed by pentanal, butanal, octanal, heptanal, noananal, acetone and toluene. These eight components comprised about 85% of the total volatiles, and the hexanal comprised about 86% total amount of the eight volatile components. the amount of the eight volatile components and hexanal in cooked glutinous rice were six and nine times more than that of cooked nonglutinous rice, respectively. The amount of volatile components in cooked glutinous rice stored for 72 hours at $70^{\circ}C$ was same with that of in nonglutinous rice immediately after cooking.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.268-272
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• 1992

Alcohol dehydrogenase activity of Clostridium acetobutylicum ATCC 4259 was studied for its specificity against substrates in acidogenic and solventogenic cultures. The bacterium reduces propionate, valerate and caproate added to the medium to the corresponding alcohols. Acetaldehyde, propionaldehyde, butyraldhyde, pentanal, and hexanal were used as the substrates by alcohol dehydrogenase, and all were reduced to the corresponding alcohols with varying affinities and reaction velocities. Acetaldehyde showed the lowest affinity and lowest velocity while the other aldehydes showed similar $K_m\;and\;V_max$ values. NADPH was used as the electron donor for the reduction of aldehydes. Alcohol dehydrogenase activity was low in acidogenic culture, and high in solventogenic culture.