• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.120-126
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• 1989

Streptococcus diacetylactis and Leuconostoc cremoris were isolated from commercial culture and the effects of culture conditions on the diacetyl production by these strains and their mixture(1:1) were investigated. Optimum temperatures and culture times for the diacetyl production by Str. diacetylactis, Leu, cremoris and their mixture were 60hr at $22^{\circ}C$(diacetyl content, 2.24ppm), 48hr at $22^{\circ}C$(2.29ppm) and 48hr at $22^{\circ}C$ (2.21ppm), respectively Optimum initial pH for the diacetyl production by Str. diacetylactis, Leu. cremoris and the mixture were all 4.8(4.32, 6.66, 7.30ppm, respectively) and optimum sodium citrate concentrations(%, w/v) were 0.30(2.58ppm), 0.1(2.54ppm) and 0.1(2.52ppm), respectively. The diacetyl contents were gradually increased according as inoculation rates(%, w/v) were increased. The amounts of diacetyl produced under optimum conditions at 24hr incubation by Str. diacetylactis, Leu. cremoris and the mixture were 4.40, 6.59 and 7.25ppm, respectively. The most effective factor affecting diacetyl production under optimum condition was pH.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.50-55
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• 2003

3,3-dichlorobenzidine is suspected to be cancinogenic in experimental animal and human. Several studies have investigated excretion of metabolites in urine, hemoglobin adduction and cancer incidence among workers occupationally exposed to 3,3'-dichlorobenzidine. In these researches, metabolites of 3,3'-dichlorobenzidine had a very important role, and were required as highly purity. The purpose of this study was synthesis and isolation of its metabolites from 3,3'-dichlorobenzidine. 3,3'-dichlorobenzidine was partially dissolved in benzene, ether, ethanol and methanol, and completely dissolved in 70% acetic acid on mixtures of citric acid containing less than 1% DCB, pyridine, a mixture of 0.5N NaOH and toluene(1:2), and phenol saturated with 20 mM TRIZA base. DCB, monoacetyl-DCB and diacetyl-DCB were measured by using gas chromatography/mass spectrometry(GC/MS). Detection for checking them was nitrogen phosphorous detection mode(NPD), and for identifying them was selected ion monitoring mode(SIM). The base peaks were 252 m/z in DCB, 252, and 294 m/z in monoacetyl-DCB, and 252, 294 and 336 m/z in diacetyl-DCB, respectively. Diacetyl-DCB was synthesized by titrating DCB solution of pyridine with sufficient acetyl chloride. Precipitation was diacetyl-DCB, which was purity of 98.7%. And its supernatant was composed of DCB, monoacetyl-DCB and diacetyl-DCB. By using acetic acid as controller of acetylation, monoacetyl-DCB was isolated from diacetyl-DCB . And residual pyridine was removed by using acetone. The purity of monoacetyl-DCB was 98.8%.

• Bulletin of the Korean Chemical Society
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• v.5 no.1
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• pp.21-23
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• 1984

The addition reactions of thioglycolic acid to ${\omega}$, ${\omega}$-diacetylstyrene derivatives were investigated. ${\omega}$, ${\omega}$-Diacetylstyrene derivatives easily undergo addition reactions with thioglycolic acid to form s-(2, 2-diacetyl-1-phenylethyl)-thiogycolic acid, s-[2,2-diacetyl-1-(methyl) phenylethyl]-thioglycolic acid, s-[2,2-diacetyl-1-(p-methoxy) phenylethyl]-thioglycolic acid and s-[2,2-diacetyl-1-(p-chloro) phenylethyl]-thioglycolic acid, respectively. The structures of these compounds were identified by neutralization equivalent, UV, IR, and NMR spectral data.

• YAKHAK HOEJI
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• v.6 no.1
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• pp.17-18
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• 1962

Several polygalitol derivatives, 4,6-benzylindene-polygalitol, 2,3-diacetyl-4,6-benzylidene-polygalitol and 2,4-diacetyl-polygalitol which might be useful to the preparation of partial condensation products of polygalitol, have been described.

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.136-141
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• 1993

A curd yogurt was prepared from milk added with skim milk powder or four kinds of cereal. The effect of cereals at 2%(w/v) level on the pattern of volatile aroma compounds in curd yogurt was investigated. Acetaldehyde, acetone, ethanol, diacetyl, butanol and acetoin in curd yogurt were detected by gas chromatographic analysis. Among these compounds, acetaldehyde, ethanol, diacetyl and acetoin were produced during fermentation by Lactobacillus acidophilus (KCTC 2182). The addition of cereals did not affect markedly general pattern of volatile aroma compounds in curd yogurt. The amount of acetoin and ethanol markedly increased until the first 6 hours of fermentation, and then increased mildly until 24 hours. The amount of diacetyl markedly increased until the first 6 hours and then decreased slightly. Acetaldehyde was first detected by gas chromatograph after 18 hours of fermentation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.45-51
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• 1986

Equimolar aqueous solutions of D-glucose and glycine were heated at $50^{\circ}C\;and\;95^{\circ}C$ at pH 6.7. The headspace volatiles and the ether extracts from the reaction mixture were analyzed by gas chromatography and gas chromatography-mass spectrometry using a fused silica capillary column. The major components formed were identified as diacetyl, three furfurals, two pyrroles, one furanone, two pyranones and two amides. In order to elucidate the formation mechanisms of the amides formed front amino-carbonyl reaction, two model systems were adopted. N-butylacetamide were formed as major components from diacetyl-butylamine ana glyoxal-butylamine systems, respectively. The results obtained suggest that such ${\alpha}-dicarbonyls$ as 3-deoxy-D-erythro-2,3-hexodiulose and diacetyl generated in the amino-carbonyl reaction react with amino compounds, amides then being formed by cleavage of the C-C bond in the ${\alpha}-dicarbonyls$.

• Korean journal of food and cookery science
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• v.11 no.3
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• pp.316-322
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• 1995

A curd yogurt was prepared from milk added with skim milk powder or four kinds of cereal. Addition of cereals markedly stimulated acid production by Leuc. mesenteroides. The acidity significantly increased during fermentation by Leuc. mesenteroides for 30 hours while pH significantly decreased during fermentation. The number of viable cells markedly increased until the first 12 or 18 hours of fermentation by Leuc. mesenteroides. Acetaldehyde, acetone, ethanol, diacetyl, butanol and acetoin in curd yogurt were detected by gas chromatographic analysis. Among these compounds, acetaldehyde, ethanol, diacetyl and acetoin were produced during fermentation by Leuc. mesenteroides.

• Food Science of Animal Resources
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• v.18 no.2
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• pp.176-184
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• 1998

The objective of this study was to investigate the effects of freezing rate on aroma retention and to examine the mechanism of aroma retention during freeze drying process. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80${\times}$20mm) containing diacetyl(2mg/ml) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom measured and diacetly contents. Besides, we observed the effect of the relative humidity of the diacetyl contents freeze-dried gelatin during storage. The retained diacetyl content was increased at high freezing temperature and in order of 0∼5, 5∼10, 10∼15, 15∼20 mm section from the bottom of the sample. It was observed that the retained diacetyl content was high in 15∼20 mm section. The retained diacetyl content and freeze-dried gelatin stored in the condition of high relative humidity was decreased significantly but in the low relative humidity case, was it decreased in small amount. The results of our experiment resents that the low temperature freezing and low humidity storing condition is effective for preserving aroma compound in food.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.373-377
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• 2001

Egg white mix (EWM) added with different ratios of cream $(10{\sim}15%,v/v)$ was fermented with Lactobacillus acidophilus (KCTC 2182) and changes of volatile aroma compounds during fermentation for 21 h were investigated. The amount of volatile aroma compounds between pre-fermented EWM, 15 h-fermented EWM, soft ice cream prepared from fermented EWM, and hard ice cream prepared from soft ice cream was compared. The results were as follows: (1) The amount of ethanol increased gradually until 9 h and increased rapidly to maximum value at 12 h and then decreased rapidly. The amount of acetone at 12 h was slightly higher, but it was not changed markedly during fermentation. Diacetyl was detected at 3 h and increased gradually to maximum value until 15 h and then decreased slightly. The amount of butanol was not changed markedly during fermentation. Acetoin was detected at 3 h and increased rapidly until 15 h and then increased gradually. (2) The amount of acetone, ethanol, diacetyl and butanol of pre-fermented sample, 15 h-fermented sample, soft ice cream and hard ice cream increased in proportion to the amount of cream added to EWM. However, the amount of butanol was relatively constant regardless of added cream ratio. The amount of volatile aroma compounds of soft ice cream was higher than that of other samlples, while that of pre-fermented sample was lower than that of other samples. Diacetyl and acetoin were not detected in pre-fermented sample.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.639-642
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• 2003

Olfactory receptor protein ODR10 was expressed in E.coli as fusion protein with GST and His6 Tag. Crude membrane extract of the expressed protein was coated on the surface of quartz crystal microbalance, and the interaction of the ODR10 with several odorants was examined. Although the expression level was very low, quartz crystal microbalance showed that the expressed protein interacted most strongly with diacetyl (butanedione), which is known to bind to the ODR10 protein selectively. The interaction between ODR10 and diacetyl was $5{\sim}10$ times stronger than the interaction between ODR10 and other odorants. Thus, E. coli cells expressing the olfactory receptor protein could be used as an olfactory biosensor. Also, such system could be used to test which olfactory receptor reacts specifically with which odorant molecules, since there has been no cheap and convenient way to test the interaction of olfactory receptors and odorant molecules yet.