2-nonenal--(trans)-isomer and 2-4-decadienal

Two types of chicken broth, broiler broth (BB) and native chicken broth (NCB), were used to analyse their differences in aroma by gas chromatography-olfactometry/mass spectrometry (GC-O/MS). NCB contained more complex volatiles and exhibited a richer aromatic profile compared with BB. Results from aroma extract dilution analysis showed that (E,E)-2,4-decadienal was the odorant with highest flavour dilution (FD) factor in both broths. The FD factors of 10 odorants in NCB were greater than those in BB, and 13 odorants with almond, citrus, vegetable, cucumber and sweet smells were only found in NCB. Moreover, 16 aroma compounds had average odor activity values (OAVs) greater than 1, among which (E,Z)-2,4-decadienal (OAV

Topics: Aldehydes; Animals; Chickens; Gas Chromatography-Mass Spectrometry; Indicator Dilution Techniques; Meat Products; Olfactometry; Smell; Volatile Organic Compounds

Off-flavor of soymilk is a barrier to the acceptance of consumers. The objectionable soy odor can be reduced through inhibition of their formation or through removal after being formed. In this study, soymilk was prepared by three grinding methods (ambient, cold, and hot grinding) from two varieties (yellow Prosoy and a black soybean) before undergoing three heating processes: stove cooking, one-phase UHT (ultrahigh temperature), and two-phase UHT process using a Microthermics direct injection processor, which was equipped with a vacuuming step to remove injected water and volatiles. Eight typical soy odor compounds, generated from lipid oxidation, were extracted by a solid-phase microextraction method and analyzed by gas chromatography. The results showed that hot grinding and cold grinding significantly reduced off-flavor as compared with ambient grinding, and hot grinding achieved the best result. The UHT methods, especially the two-phase UHT method, were effective to reduce soy odor. Different odor compounds showed distinct concentration patterns because of different formation mechanisms. The two varieties behaved differently in odor formation during the soymilk-making process. Most odor compounds could be reduced to below the detection limit through a combination of hot grinding and two-phase UHT processing. However, hot grinding gave lower solid and protein recoveries in soymilk.

Topics: Aldehydes; Chromatography, Gas; Food Handling; Furans; Glycine max; Hexanols; Hot Temperature; Ketones; Lipoxygenase; Odorants; Solid Phase Microextraction; Soy Milk; Soybean Proteins; Taste; Volatile Organic Compounds

Glutathione transferases (GSTs) are believed to be a major detoxification system in helminths. We describe the expression and functional analysis of EgGST, a cytosolic GST from Echinococcus granulosus, related to the Mu-class of mammalian enzymes. EgGST was produced as an enzymatically active dimeric protein (rEgGST), with highest specific activity towards the standard substrate 1-chloro-2,4-dinitrobenzene (CDNB; 2.5 micromol min(-1)mg(-1)), followed by ethacrynic acid. Interestingly, rEgGST displayed glutathione peroxidase activity (towards cumene hydroperoxide), and conjugated reactive carbonyls (trans-2-nonenal and trans,trans-2,4-decadienal), indicating that it may intercept damaging products of lipid peroxidation. In addition, classical GST inhibitors (cybacron blue, triphenylthin chloride and ellagic acid) and a number of anthelmintic drugs (mainly, hexachlorophene and rafoxanide) were found to interfere with glutathione-conjugation to CDNB; suggesting that they may bind to EgGST. Considered globally, the functional properties of rEgGST are similar to those of putative orthologs from Echinococcus multilcularis and Taenia solium, the other medically important cestodes. Interestingly, our results also indicate that differences exist between these closely related cestode GSTs, which probably reflect specific biological functions of the molecules in each parasitic organism.

Topics: Aldehydes; Animals; Benzene Derivatives; Dimerization; Dinitrochlorobenzene; Echinococcus granulosus; Enzyme Inhibitors; Ethacrynic Acid; Glutathione Peroxidase; Glutathione Transferase; Recombinant Proteins; Substrate Specificity

An investigation on the odor-active compounds of wholemeal (WWF) and white wheat flour (WF 550) by aroma extract dilution analysis (AEDA) and by quantitative studies using stable isotope dilution assays (SIDA) revealed a significant number of odor-active compounds, such as (E)-2-nonenal, (E,Z)- and (E,E)-2,4-decadienal, (E)-4,5-epoxy-(E)-2-decenal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, and vanillin, with high odor activities in both wheat flours. The amounts and, consequently, the aroma potencies of vanillin, (E,E)-2,4-decadienal, and 3-(methylthio)propanal were much higher in the WWF than in the WF 550 samples. Fermentation of suspensions of both flours with lactic acid bacteria did not generate new odorants; however, many compounds, such as acetic acid or 3-methylbutanal, were increased, whereas aldehydes (formed from the degradation of unsaturated fatty acids) were decreased. Comparing the odorant concentrations present before and after fermentation gave evidence that the main influence of the microorganisms on sourdough aroma is to either enhance or decrease specific volatiles already present in the flour. A comparison with literature data indicated that most of these odorants are also important for the bread crumb aroma present after baking of the dough.

Topics: Aldehydes; Benzaldehydes; Bread; Fermentation; Flour; Indicator Dilution Techniques; Odorants; Triticum

The structures of fluorescent products formed in the reaction of methyl linoleate hydroperoxides with adenine, FeSO4 and ascorbic acid were investigated to elucidate the mechanism of interaction. The fluorescent products consisted of at least four major components (I-IV), which could be separated by thin-layer chromatography and high-performance liquid chromatography. Both 2-octenal and 2,4-decadienal, degradation products of methyl linoleate hydroperoxides, reacted with adenine to produce a fluorescent product similar to one of the major compounds (II) formed in the reaction of methyl linoleate hydroperoxides. Spectroscopic data suggest that I and III are the same type of compounds, which have closed ring structures with alpha, beta-unsaturated carbonyl groups between the amino group at the 6-position and the nitrogen at the 1-position of adenine. Component II has a closed ring structure at the same site as I and III, and the presence of an ether linkage was suggested. On the basis of these structures, the involvement of 3-nonenal, methyl 12-oxo-9-dodecenoate and 2-octenal was suggested in the interaction of the methyl linoleate hydroperoxides decomposition products and adenine or DNA in the presence of FeSO4 and ascorbic acid.

Topics: Adenine; Aldehydes; Ascorbic Acid; Chemical Phenomena; Chemistry; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; DNA; Ferrous Compounds; Fluorescence; Lipid Peroxides; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Spectrometry, Fluorescence