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Headspace Volatiles (headspace + volatile)
Selected AbstractsAnalysis of Headspace Volatile and Oxidized Volatile Compounds in DHA-enriched Fish Oil on Accelerated Oxidative StorageJOURNAL OF FOOD SCIENCE, Issue 7 2003H. Lee ABSTRACT: Oxidative stability of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and volatile and oxidized volatile compounds in 2 types of DHA-enriched fish oil, triacylglycerol (TG) and ethyl ester (EE), were studied during storage at 80 °C with aeration. The rate of DHA autoxidation was higher than that of EPA. DHA in EE form was more susceptible to autoxidation than in TG form. Thirty-one volatile compounds were identified in EE and 23 volatile compounds in TG. (E)-2-pentenal, 2-(1-pentenyl) furan, and (E,E)-2,4-heptadienal were commonly detected as oxidized volatile compounds from TG and EE fish oil. These volatile oxidized compounds might be formed mainly from the oxidation of DHA and EPA, the main fatty acids of the oil. [source] Changes of Volatile Compounds, Lactic Acid Bacteria, pH, and Headspace Gases in Kimchi, a Traditional Korean Fermented Vegetable ProductJOURNAL OF FOOD SCIENCE, Issue 3 2003J.H. Kang ABSTRACT Headspace volatiles of Kimchi stored at 5 °C increased over a 7 d period by 20.0% and then decreased from 7 to 27 d by 8.3%. Forty volatile compounds including 18 sulfur compounds were identified in Kimchi. Lactic acid bacteria in Kimchi increased from 3.1 to 4.5 (1 × 108cfu/mL) over a 17-d period and decreased by 40% from 17 to 27 d. As the storage time increased from 2 to 27 d, pH decreased from 4.3 to 3.8, headspace oxygen decreased from 14.3 to 1.3%, and headspace carbon dioxide increased from 27.7 to 45.3%. Enzymatic reactions and chemical oxidations in Kimchi explained the changes of volatile compounds, lactic acid bacteria, pH, headspace oxygen and carbon dioxide. [source] Monitoring of headspace volatiles in milk-cereal-based liquid infant foods during storageEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 12 2006Guadalupe García-Llatas Abstract The effect of storage (time and temperature) on the evolution of pentanal, hexanal, heptanal and pentane as volatile lipid oxidation products in two liquid ready-to-eat milk-cereal-based infant foods was studied. An SPME-GC method was used to this effect. Samples were stored for 9,months at 25, 30 and 37,°C and tested eight times during this period. Freshly produced infant foods contained pentanal, hexanal and heptanal (mean values: 10.71, 71.5 and 1.2,µg/kg, respectively), which decreased during the first 3,months of storage, although from the fourth month onwards no significant differences among storage times were found. Aldehyde content was inversely proportional to storage temperature. Pentane content was directly proportional to storage temperature and increased (19.9,µg/kg at zero time) over all months of storage up to 43.1,µg/kg. [source] Volatile compounds of original African black and white shea butter from Tchad and CameroonEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2006Sabine Krist Abstract Shea butter is used as an edible vegetable fat in many African countries. It can be utilized as a substitute or complete replacement for cocoa butter in various applications and plays an important role in traditional African medicinal practice. Although detection of volatile compounds by solid-phase micro-extraction gas-chromatography mass-spectroscopy (SPME-GC-MS) is a very reliable and reproducible technique, which can be used as an important part of authenticity checking, production monitoring and contamination detection, no published data about volatile compounds of shea butter are available so far. In this investigation, the characteristic volatiles in the headspace of original African shea butter samples were identified by using SPME-capillary-GC coupled to a mass selective detector. Almost 100,different volatile components were identified, e.g. fatty acids, saturated and unsaturated aldehydes and ketones, terpenes, and typical Maillard reaction products such as methylfuranes and pyrazines. Furthermore, the samples have been olfactorily evaluated by a panel of professional flavorists and trained analytical chemists. It can be stated that variations in processing conditions of shea butter result in considerable differences in the composition of headspace volatiles, detected by SPME-GC-MS and human olfaction. [source] Substrate specificity and inhibition of brassinin hydrolases, detoxifying enzymes from the plant pathogens Leptosphaeria maculans and Alternaria brassicicolaFEBS JOURNAL, Issue 24 2009M. Soledade C. Pedras Blackleg (Leptosphaeria maculans and Leptosphaeria biglobosa) and black spot (Alternaria brassicicola) fungi are devastating plant pathogens known to detoxify the plant defence metabolite, brassinin. The significant roles of brassinin as a crucifer phytoalexin and as a biosynthetic precursor of several other plant defences make it important in plant fitness. Brassinin detoxifying enzymes produced by L. maculans and A. brassicicola catalyse the detoxification of brassinin by hydrolysis of its dithiocarbamate group to indolyl-3-methanamine. The purification and characterization of brassinin hydrolases produced by L. maculans (BHLmL2) and A. brassicicola (BHAb) were accomplished: native BHLmL2 was found to be a tetrameric protein with a molecular mass of 220 kDa, whereas native BHAb was found to be a dimeric protein of 120 kDa. Protein characterization using LC-MS/MS and sequence alignment analyses suggested that both enzymes belong to the family of amidases with the catalytic Ser/Ser/Lys triad. Furthermore, chemical modification of BHLmL2 and BHAb with selective reagents suggested that the amino acid serine was involved in the catalytic activity of both enzymes. The overall results indicated that BHs have new substrate specificities with a new catalytic activity that can be designated as dithiocarbamate hydrolase. Investigation of the effect of various phytoalexins on the activities of BHLmL2 and BHAb indicated that cyclobrassinin was a competitive inhibitor of both enzymes. On the basis of pH dependence, sequence analyses, chemical modifications of amino acid residues and identification of headspace volatiles, a chemical mechanism for hydrolysis of the dithiocarbamate group of brassinin catalysed by BHLmL2 and BHAb is proposed. The current information should facilitate the design of specific synthetic inhibitors of these enzymes for plant treatments against blackleg and black spot fungal infections. [source] Composition of essential oil, concrete, absolute, wax and headspace volatiles of Murrarya paniculata (Linn.) Jack flowersFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2007P. K. Rout Abstract Murraya paniculata (Linn) Jack, syn. M. exotica Linn., commonly known as orange jessamine, is grown in gardens for its large clusters of fragrant flowers. Distillation of the fresh flowers in water furnished the essential oil in 0.027% yield. Extraction of the fresh flowers with pentane afforded the concrete (0.78%). Precipitating the waxes from the concrete with methanol gave absolute (0.62%). The chemical composition of essential oil, concrete, absolute and wax were analysed by GC and GC,MS. The components of essential oil in significant amounts were , -elemene (1.4%), (E)-caryophyllene (3.6%), germacrene D (2.7%), (E)-nerolidol (25.7%), benzyl benzoate (8.1%), phenyl ethyl benzoate (8.0%) and manool (18.7%). The major components in the concrete and absolute, respectively, were phenyl ethyl alcohol (2.9%, 3.0%), indole (0.8%, 1.0%), (E)-nerolidol (6.5%, 7.0%), benzyl benzoate (5.0%, 6.5%), phenyl ethyl benzoate (8.0%, 8.6%) and manool (25.2%, 27.9%). The methanol-insoluble wax contained (E)-nerolidol (2.6%), manool (9.4%) and most of the fatty acids/esters. The composition of the volatile components in the headspace emitted by flowers still on the branch (live flowers) and also by the picked flowers was determined by HS,SPME on a PDMS fibre and these results are also presented. The major components found in the headspace were linalool, indole, (E)-caryophyllene, germacrene D, bicyclogermacrene and (E,E)- , -farnesene. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of Gamma-irradiation on Color, Pungency, and Volatiles of Korean Red Pepper PowderJOURNAL OF FOOD SCIENCE, Issue 8 2004J.H. Lee ABSTRACT: Effect of gamma-irradiation on color, pungency, and volatiles of Korean red pepper powder (Capsicum annuum L.) was investigated. Red pepper powder, vacuum-packaged in a polyethylene/polypropylene bag, was gamma-irradiated up to 7 kGy. An irradiation dose of 7 kGy reduced the population of mesophilic bacteria and fungi effectively without affecting major quality factors. Pungency of irradiated red pepper powder was not changed based on the amount of capsanoids by high-performance liquid chromatography (HPLC) and the Scoville sensory score. The red color of irradiated pepper powder was not significantly different from that of the control, judged from the capsanthin content by HPLC and color assessment using spectrophotpmetric (American Spice Trade Assn. units) and colorimetric measurements (Hunter a values). Further, the sensory evaluation showed no significant difference in pungent odor and off-odor between nonirradiated control and irradiated red pepper powder. However, when headspace volatiles of gamma-irradiated red pepper powder were evaluated by gas chromatography/ mass spectrometry with solid-phase microextraction and electronic nose with metal oxide sensors, the profiles of odor were classified into irradiated dose levels of 0, 3, 5, and 7 kGy by principal component analysis and multivariate analysis of variance. Such a difference of odor might result from the disappearance of some volatiles, such as hexanoic acid and tetramethyl-pyrazine, and the appearance of 1,3-di-tert-butylbenzene during irradiation. Moreover, it appears that the irradiation of packaging material induced a formation of 1,3-di-tertbutylbenzene, which migrated into the red pepper powder. [source] Early-Season Headspace Volatiles from Apple and Their Effect on the Apple Blossom Weevil Anthonomus pomorumCHEMISTRY & BIODIVERSITY, Issue 9 2010Rafal Piskorski Abstract Apple volatiles emitted at early phenological stages are little investigated, although they may influence behavior of early-season pests. The apple blossom weevil Anthonomus pomorum is a herbivore pest of orchards in Europe. It colonizes apple trees in early season and oviposits into developing flower buds, often leading to economic damage. Using in situ radial diffusive sampling and thermal desorption, followed by GC/MS analysis, headspace volatiles from apple twigs with flower buds at three early phenological tree stages were identified and quantified. The volatile blend consisted of 13,compounds for the first, and increased to 15 compounds for the third phenological stage sampled. These blends included benzenoids, terpenes, and derivatives of fatty acids. A recombined synthetic blend served as the odor source in a still-air dual-choice olfactometer bioassay, in which individual male and female weevils were tested. Results from this behavioral test document an attraction of both sexes to odors of their host plant, suggesting that apple volatiles emitted in early season serve as olfactory cues for host location of A. pomorum in the field. [source] | ||||||||||