Comparative Volatile Profiles in Soy Sauce According to Inoculated Microorganisms

We compared the volatile profiles in soy sauce according to inoculation with Tetragenococcus halophilus and/or Zygosaccharomyces rouxii. Totals of 107 and 81 volatiles were respectively identified by using solid-phase microextraction and solvent extraction. The various volatile compounds identified included acids, aldehydes, esters, ketones, furans and furan derivatives, and phenols. The major volatiles in the samples treated with T. halophilus were acetic acid, formic acid, benzaldehyde, methyl acetate, ethyl 2-hydroxypropanoate, 2-hydroxy-3-methyl-2-cyclopenten-1-one, and 4-hydroxy-3-methoxybenzaldehyde, while those in the samples inoculated with Z. rouxii were mainly ethanol, acetaldehyde, ethyl propanoate, 2/3-methylbutanol, 1-butanol, 2-phenylethanol, ethyl 2-methylpropanoate, and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone. The results indicate that T. halophilus produced significant acid compounds and could affect the Z. rouxii activity, supporting the notion that yeasts and lactic acid bacteria respectively have different metabolic pathways of alcoholic fermentation and lactic acid fermentation, and produce different dominant volatile compounds in soy sauce.     

Volatile constituents of glutathione--ribose model system and its antioxidant activity

Summary.  Reaction between glutathione and ribose was carried out to study the volatiles formed via Maillard reaction and their antioxidant activity as well as their role in inhibition of LDL oxidation. The simultaneous distillation – extraction technique was used for trapping the volatile components followed by GC – MS analysis. Thirty six compounds were identified with the predominance of carbonyls and sulfur – containing compounds in the volatiles of this model system. Sensory evaluation was performed for the model system product according to the International Standard Methods (ISO). The results showed a high decrease in roasted and burnt attributes and remarkable increase in the like – boiled and roasted meat attributes. The sensory results of the model system product were confirmed by the presence of high concentrations of some volatile compounds having meat – like aroma such as 2-methyl-3-furanthiol and 2-furylmethanethiol. The radical scavenging activity of glutathione – ribose model system was quantified spectrophotometrically, using DPPH radical. The activity of the model system product was found to be slightly lower than that of gallic acid and BHA, but it was much higher than that of cinnamic acid (200 ppm. for each). A highly antioxidative activity was recorded by the model system product during the inhibition of LDL – oxidation in comparison with L-ascorbic acid as well as reduced glutathione (as a concentration of 0.5 μmol/L, for each) which may be due to the presence of some compounds such as 2-furylmethanethiol, 2-acetyl thiazole, 4-hydroxy-5-methyl-3(2H)-furanone. Received October 15, 2001 Accepted April 3, 2002 Published online September 4, 2002 Authors' address:  Khaled Farouk El-massry, Flavour and Aromatic Chemistry Department, National Research Center, Tahrir st., Dokki, Cairo, Egypt, Fax: 002 02 337 0 931, E-mail: kfarouk@yahoo.com     

Structural Basis for the Enzymatic Formation of the Key Strawberry Flavor Compound 4-Hydroxy-2,5-dimethyl-3(2H)-furanone

The last step in the biosynthetic route to the key strawberry flavor compound 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) is catalyzed by Fragaria x ananassa enone oxidoreductase (FaEO), earlier putatively assigned as quinone oxidoreductase (FaQR). The ripening-induced enzyme catalyzes the reduction of the exocyclic double bond of the highly reactive precursor 4-hydroxy-5-methyl-2-methylene-3(2H)-furanone (HMMF) in a NAD(P)H-dependent manner. To elucidate the molecular mechanism of this peculiar reaction, we determined the crystal structure of FaEO in six different states or complexes at resolutions of ≤1.6 Å, including those with HDMF as well as three distinct substrate analogs. Our crystallographic analysis revealed a monomeric enzyme whose active site is largely determined by the bound NAD(P)H cofactor, which is embedded in a Rossmann-fold. Considering that the quasi-symmetric enolic reaction product HDMF is prone to extensive tautomerization, whereas its precursor HMMF is chemically labile in aqueous solution, we used the asymmetric and more stable surrogate product 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone (EHMF) and the corresponding substrate (2E)-ethylidene-4-hydroxy-5-methyl-3(2H)-furanone (EDHMF) to study their enzyme complexes as well. Together with deuterium-labeling experiments of EDHMF reduction by [4R-²H]NADH and chiral-phase analysis of the reaction product EHMF, our data show that the 4R-hydride of NAD(P)H is transferred to the unsaturated exocyclic C6 carbon of HMMF, resulting in a cyclic achiral enolate intermediate that subsequently becomes protonated, eventually leading to HDMF. Apart from elucidating this important reaction of the plant secondary metabolism our study provides a foundation for protein engineering of enone oxidoreductases and their application in biocatalytic processes.     

Preparation of reminiscent aroma mixture of Japanese soy sauce

To prepare an aroma mixture of Japanese soy sauce by fewest components, the aroma concentrate of good sensory attributes was prepared by polyethylene membrane extraction, which could extract only the volatiles with diethyl ether. GC-MS-Olfactometry was done with the aroma concentrate, and 28 odor-active compounds were detected. Application of aroma extract dilution analysis to the separated fraction revealed high flavor dilution factors with respect to acetic acid, 4-hydroxy-2(or5)-ethyl-5(or2)-methyl-3(2H)-furanone (HEMF), 3-methyl-1-butanol (isoamyl alcohol), and 3-(methylsulfanyl)propanal (methional). A model aroma mixture containing above four odorants showed a good similarity with the aroma of the soy sauce itself. Consequently, the reminiscent aroma mixture of soy sauce was prepared in water. The ratio of acetic acid, HEMF, isoamyl alcohol, and methional was 2500:300:100:1.     

Flavor Components of Roasted Almond

Roasted almond volatiles were separated into basic, carbonyl and non-carbonyl fractions. Each fraction was analyzed by combination gas chromatography-mass spectrometry. Twenty-five compounds, in addition to eighteen known components, were identified. Many of the components identified were considered to contribute to the overall flavor. 2,5-Dimethyl-4- hydroxy-3(2H)-furanone, which was identified from methanol extract of roasted almond, seemed to make the largest contribution to the sweet aroma of roasted almond.     

Genotoxic effects of the chlorinated hydroxyfuranones 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone and 3,4-dichloro-5-hydroxy-2[5H]-furanone in Tradescantia micronucleus assays

This is the first report of clastogenic effects of chlorinated hydroxyfuranones (CHFs) in plants. Two byproducts of water chlorination, 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX) and 3,4-dichloro 5-hydroxy-2[5H]-furanone (MA) induced a dose dependent increase of micronuclei (MN) in pollen mother cells of Tradescantia when doses up to 100 μg MX and 500 μg MA were applied directly to the inflorescences. In contrast, exposure of the stems in aqueous solutions containing up to 1 mg/I MX and 10 mg/I MA did not cause a positive response.     

Aroma compounds in Japanese sweet rice wine (Mirin) screened by aroma extract dilution analysis (AEDA)

Thirty-nine key aroma compounds were newly identified or tentatively identified in the aroma concentrate of Japanese sweet rice wine (Mirin) by an aroma extract dilution analysis technique based on the 68 detected peaks. Among them, 3-(methylthio)propanal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 3-methylbutanoic acid, 2-methylbutanoic acid, and 2-methoxy-4-vinylphenol were detected with the highest FD factors in this study.     

Serotonergic Agonists Inhibit Calcium-Activated Potassium and Voltage-Dependent Sodium Currents in Rat Taste Receptor Cells

Recently we reported that rat taste receptor cells respond to the neurotransmitter serotonin with an inhibition of a calcium-activated potassium current [17]. In the present study, this observation is confirmed and extended by studying the effects of an array of serotonergic agonists on membrane properties, calcium-activated potassium current, and voltage-dependent sodium current in taste receptor cells using the patch-clamp recording technique in the whole-cell configuration. Serotonergic inhibition of calcium-activated potassium current was mimicked by the agonists N-(3-trifluoromethylphenyl)piperazine and by (±)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene. Both produced reversible inhibition of K _Ca as well as significantly increasing the input resistance of the cell. The agonists 1-(1-naphthyl)piperazine and buspirone (both serotonin receptor 1A agonists) were similarly effective in reducing K _Ca . Outward current was unaffected by application of phenylbiguanide, a serotonin receptor 3 agonist, though current was affected by subsequent application of (±)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene. Two agonists—N-(3-trifluoromethylphenyl)piperazine and (±)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene—were also tested on voltage-dependent sodium currents; both were effective and reversible in reducing its magnitude at a variety of applied potentials. These data are consistent with the notion that serotonin effects in rat taste receptor cells are mediated by serotonin 1A receptors, though other receptor subtypes may be additionally expressed. Serotonin may affect the taste cell electrical properties during active stimulation in a paracrine fashion. Received: 10 May 1999/Revised: 27 September 1999     

Biosynthesis of flavour-active furanones by Saccharomyces cerevisiae during fermentation depends on the malt type used in medium preparation

Extracts of a coloured malt contained 4-hydroxy-5-monomethyl-3(2H)-furanone (HMMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) but not 4-hydroxy-5(or 2)-ethyl-2(or 5)-methyl-3(2H)-furanone (HEMF). Extracts of a pale malt did not contain any of the furanones. HMMF and HDMF were produced by Saccharomyces cerevisiae during fermen-tation of both types of malt extract. About 0.09 mg HEMF l ⁻¹ was synthesised during fermentation of the coloured malt extract but none was produced with the pale malt extract. Final concentrations of HDMF (2.0 mgl ⁻¹) and HEMF (0.09 mgl ⁻¹) were in excess of their aroma threshold values in water (0.16 and 0.02 mgl ⁻¹ respectively) after fermen-tation of the coloured malt extract. This revised version was published online in November 2006 with corrections to the Cover Date.     

Composition of Semivolatiles from Roasted Tobacco

In order to examine the applicability of the exhaust gas components from the tobacco-roasting process as cigarette flavor ingredients, a preliminary study on the composition of the semivolatiles included in the volatiles from roasted tobacco was conducted. A relatively large quantity of sugar pyrolysates (furans, volatile ketones and lactones) in addition to lower fatty acids and the components of essential oils were found in the condensate of the volatiles from roasted flue-cured tobacco. The condensate from roasted burley tobacco contained nicotine and neophytadiene as major components, and a number of other components of essential oils were also found. The above mentioned compounds in the condensate from flue-cured tobacco were assumed to contribute to its burnt-sugar like aroma. A sweet note of the condensate from burley tobacco might be attributable to the high concentration of the components of essential oils.     

Action of Poly-l-malic Acid on Various Proteolytic Enzymes

The steam volatile neutral fraction of tobacco smoke condensates was separated into n-hexane, nitromethane and 1:4 water-methanol soluble fractions by solvent partition.

2.methyl-4-hydroxy-2-hexenoic acid lactone, dihydroactinidiolide and phthalide were isolated from the 1:4 water-methanol soluble fraction, the highly polar portion of the steam volatile neutral fraction was designated as the M fraction.

By continuing analysis of the M fraction from a previous paper, benzyl alcohol, phenyl-ethyl alcohol, pyrrole-2-aldehyde, α-pyrrylmethylketone, α-pyrrylethylketone, α-carbomethoxypyrrole, pyrrole-2-carbonitrile, methyl-pyrrole-2-carbonitrile, 3-methyl-, 3-ethyl-, 3-n-propyl-, 2,3-dimethyl-, 2-ethyl-3-methyl-2-cyclopentene-1-one and norsolanadione were identified.

Identification of the compounds was based on the spectroscopic method (IR, MS, UV and GC-MS) and gas chromatographic analysis.     

New butenolides from Aspergillus terreus

From the culture filtrate of Aspergillus terreus, seven related yellow substances were isolated and the simplest, C₁₇H₁₂O₅, was proved to be 3-(p-hydroxyphenyl)-4-hydroxy-5-(p-hydroxybenzylidene)-2(5H)-furanone.     

Fluorescent labeling of proteins. A new methodology

A new reagent, 2-methoxy-2,4-diphenyl-3(2$\text{H}$)-furanone (MDPF) has been utilized for the fluorescent labeling of proteins. MDPF, which is nonfluorescent, reacts with primary amino groups to form fluorescent $\text{N}$-substituted 3,5-diphenyl-5-hydroxy-2-pyrrolin-4-ones. Antibodies labeled with MDPF afford intense immunofluorescent staining.     

Novel Dithiazine Compounds in Volatile Components from Cooked Sakuraebi (Sergia lucens Hansen)

Three novel dithiazine compounds in the aroma concentrate from cooked sakuraebi, Sergia lucens Hansen, were isolated. Their structures were confirmed as 4,6-dimethyl-2-propyl-1,3,5-dihydrodithiazine (A), 4-butyl-2,6-dimethyl-1,3,5-dihydrodithiazine (B) and pyrrolidino[1,2-e]4H-2,4-dimethyl-1,3,5-dithiazine (C) by spectroscopic analyses. The same compounds have also been found in the aroma concentrate from cooked krill. These three compounds were newly discovered as food volatiles, and among them, compound C seems to take an important role in the aroma of cooked small shrimp by its strong roasted aroma and its relatively high concentration.     

Studies on Flavor Components of Roasted Barley

From the volatiles of roasted barley or those formed during roasting of barley, furfural, 2-methylbutanal, 2-methylpropanal, 3-methylbutanal, 2,3-pentanedione, ethylglyoxal and pyruvaldehyde were isolated and identified as their mono- or bis-2,4-dinitrophenylhydrazones.

Removal of the carbonyl compounds from the volatiles resulted in a loss of the characteristic aroma of roasted barley.     

2,3-Dimethylpyrazine (3DP) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) generated by the Maillard reaction in foods affect autonomic nervous activity and central nervous activity in human

ABSTRACT

This study investigated the effect of the odors generated by the glycine/glucose Maillard reaction and the potent odorants 2,3-dimethylpyrazine (3DP) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) on the human mood and integrative physiological activity. The score of certain subjective moods, especially anger-hostility, and tension-anxiety were decreased significantly after inhalation of the Maillard reaction sample and DMHF, and fatigue-inertia mood was also significantly decreased by DMHF, suggesting a sedative effect of these odors on mood, while 3DP had no effect. Miosis rate and fingertip temperature increased significantly following inhalation of the odor from the Maillard reaction sample and both potent odorants, suggesting that the parasympathetic nervous system dominates through suppression of the sympathetic activity. The physiological relaxing effect of these odors was also confirmed by decreased flicker frequency value and decreased oxyhemoglobin in the prefrontal cortex.     

Identification of 4,5-Dimethyl-3-hydroxy-2(5H)-furanone (Sotolon) and Ethyl 9-Hydroxynonanoate in Botrytised Wine and Evaluation of the Roles of Compounds Characteristic of It

Two new components of botrytised wine were identified: 4,5-dimethyl-3-hydroxy-2(5H)-furanone (Sotolon) and ethyl 9-hydroxynonanoate. Sotolon, the key substance of cane sugar aroma, was identified as the sugary flavor substance of botrytised wine by means of gas chromatography-mass spectrometry after column chromatographic separation on DEAE-Sephadex and silica gel. Ethyl 9-hydroxynonanoate was identified by chemical ionization and electron impact mass spectrometry. To evaluate the role of 17 volatile and 5 nonvolatile compounds characteristic of botrytised wine, these compounds were added to a normal wine. This produced a sweet, honey-like flavor similar to that of botrytised wine. The importance of Sotolon and the role of each group of flavor substances in producting this flavor was clarified by omission tests.